ex (1)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.NAME
ex --- text editorSYNOPSIS
ex [-rR] [-s|-v] [-c command] [-t tagstring] [-w size] [file...]
DESCRIPTION
The ex utility is a line-oriented text editor. There are two other modes of the editor---open and visual---in which screen-oriented editing is available. This is described more fully by the ex open and visual commands and in vi. If an operand is '-', the results are unspecified. This section uses the term edit buffer to describe the current working text. No specific implementation is implied by this term. All editing changes are performed on the edit buffer, and no changes to it shall affect any file until an editor command writes the file. Certain terminals do not have all the capabilities necessary to support the complete ex definition, such as the full-screen editing commands (visual mode or open mode). When these commands cannot be supported on such terminals, this condition shall not produce an error message such as ``not an editor command'' or report a syntax error. The implementation may either accept the commands and produce results on the screen that are the result of an unsuccessful attempt to meet the requirements of this volume of POSIX.1-2008 or report an error describing the terminal-related deficiency.OPTIONS
The ex utility shall conform to the Base Definitions volume of POSIX.1-2008, Section 12.2, Utility Syntax Guidelines, except for the unspecified usage of '-', and that '+' may be recognized as an option delimiter as well as '-'. The following options shall be supported:- -c command
- Specify an initial command to be executed in the first edit buffer loaded from an existing file (see the EXTENDED DESCRIPTION section). Implementations may support more than a single -c option. In such implementations, the specified commands shall be executed in the order specified on the command line.
- -r
-
Recover the named files (see the EXTENDED DESCRIPTION section).
Recovery information for a file shall be saved during an editor or
system crash (for example, when the editor is terminated by a signal
which the editor can catch), or after the use of an
ex
preserve
command.
-
A crash in this context is an unexpected failure of the system or utility that requires restarting the failed system or utility. A system crash implies that any utilities running at the time also crash. In the case of an editor or system crash, the number of changes to the edit buffer (since the most recent preserve command) that will be recovered is unspecified. If no file operands are given and the -t option is not specified, all other options, the EXINIT variable, and any .exrc files shall be ignored; a list of all recoverable files available to the invoking user shall be written, and the editor shall exit normally without further action.
-
- -R
- Set readonly edit option.
- -s
-
Prepare
ex
for batch use by taking the following actions:
-
- *
- Suppress writing prompts and informational (but not diagnostic) messages.
- *
- Ignore the value of TERM and any implementation default terminal type and assume the terminal is a type incapable of supporting open or visual modes; see the visual command and the description of vi.
- *
- Suppress the use of the EXINIT environment variable and the reading of any .exrc file; see the EXTENDED DESCRIPTION section.
- *
- Suppress autoindentation, ignoring the value of the autoindent edit option.
-
- -t tagstring
- Edit the file containing the specified tagstring; see ctags. The tags feature represented by -t tagstring and the tag command is optional. It shall be provided on any system that also provides a conforming implementation of ctags; otherwise, the use of -t produces undefined results. On any system, it shall be an error to specify more than a single -t option.
- -v
- Begin in visual mode (see vi).
- -w size
- Set the value of the window editor option to size.
OPERANDS
The following operand shall be supported:- file
- A pathname of a file to be edited.
STDIN
The standard input consists of a series of commands and input text, as described in the EXTENDED DESCRIPTION section. The implementation may limit each line of standard input to a length of {LINE_MAX}. If the standard input is not a terminal device, it shall be as if the -s option had been specified. If a read from the standard input returns an error, or if the editor detects an end-of-file condition from the standard input, it shall be equivalent to a SIGHUP asynchronous event.INPUT FILES
Input files shall be text files or files that would be text files except for an incomplete last line that is not longer than {LINE_MAX}-1 bytes in length and contains no NUL characters. By default, any incomplete last line shall be treated as if it had a trailing <newline>. The editing of other forms of files may optionally be allowed by ex implementations. The .exrc files and source files shall be text files consisting of ex commands; see the EXTENDED DESCRIPTION section. By default, the editor shall read lines from the files to be edited without interpreting any of those lines as any form of editor command.ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of ex:- COLUMNS
- Override the system-selected horizontal screen size. See the Base Definitions volume of POSIX.1-2008, Chapter 8, Environment Variables for valid values and results when it is unset or null.
- EXINIT
- Determine a list of ex commands that are executed on editor start-up. See the EXTENDED DESCRIPTION section for more details of the initialization phase.
- HOME
- Determine a pathname of a directory that shall be searched for an editor start-up file named .exrc; see the EXTENDED DESCRIPTION section.
- LANG
- Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1-2008, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)
- LC_ALL
- If set to a non-empty string value, override the values of all the other internationalization variables.
- LC_COLLATE
-
Determine the locale for the behavior of ranges, equivalence classes, and multi-character collating elements within regular expressions. - LC_CTYPE
- Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments and input files), the behavior of character classes within regular expressions, the classification of characters as uppercase or lowercase letters, the case conversion of letters, and the detection of word boundaries.
- LC_MESSAGES
-
Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error. - LINES
- Override the system-selected vertical screen size, used as the number of lines in a screenful and the vertical screen size in visual mode. See the Base Definitions volume of POSIX.1-2008, Chapter 8, Environment Variables for valid values and results when it is unset or null.
- NLSPATH
- Determine the location of message catalogs for the processing of LC_MESSAGES.
- PATH
- Determine the search path for the shell command specified in the ex editor commands !, shell, read, and write, and the open and visual mode command !; see the description of command search and execution in Section 2.9.1.1, Command Search and Execution.
- SHELL
- Determine the preferred command line interpreter for use as the default value of the shell edit option.
- TERM
- Determine the name of the terminal type. If this variable is unset or null, an unspecified default terminal type shall be used.
ASYNCHRONOUS EVENTS
The following term is used in this and following sections to specify command and asynchronous event actions:- complete write
-
A complete write is a write of the entire contents of the edit buffer to a file of a type other than a terminal device, or the saving of the edit buffer caused by the user executing the ex preserve command. Writing the contents of the edit buffer to a temporary file that will be removed when the editor exits shall not be considered a complete write. The following actions shall be taken upon receipt of signals: - SIGINT
-
If the standard input is not a terminal device,
ex
shall not write the file or return to command or text input mode, and
shall exit with a non-zero exit status.
-
Otherwise, if executing an open or visual text input mode command, ex in receipt of SIGINT shall behave identically to its receipt of the <ESC> character. Otherwise:- 1.
- If executing an ex text input mode command, all input lines that have been completely entered shall be resolved into the edit buffer, and any partially entered line shall be discarded.
- 2.
-
If there is a currently executing command, it shall be aborted and a
message displayed. Unless otherwise specified by the
ex
or
vi
command descriptions, it is unspecified whether any lines modified by
the executing command appear modified, or as they were before being
modified by the executing command, in the buffer.
-
If the currently executing command was a motion command, its associated command shall be discarded.
-
- 3.
- If in open or visual command mode, the terminal shall be alerted.
- 4.
- The editor shall then return to command mode.
-
- SIGCONT
- The screen shall be refreshed if in open or visual mode.
- SIGHUP
- If the edit buffer has been modified since the last complete write, ex shall attempt to save the edit buffer so that it can be recovered later using the -r option or the ex recover command. The editor shall not write the file or return to command or text input mode, and shall terminate with a non-zero exit status.
- SIGTERM
- Refer to SIGHUP. The action taken for all other signals is unspecified.
STDOUT
The standard output shall be used only for writing prompts to the user, for informational messages, and for writing lines from the file.STDERR
The standard error shall be used only for diagnostic messages.OUTPUT FILES
The output from ex shall be text files.EXTENDED DESCRIPTION
Only the ex mode of the editor is described in this section. See vi for additional editing capabilities available in ex. When an error occurs, ex shall write a message. If the terminal supports a standout mode (such as inverse video), the message shall be written in standout mode. If the terminal does not support a standout mode, and the edit option errorbells is set, an alert action shall precede the error message. By default, ex shall start in command mode, which shall be indicated by a : prompt; see the prompt command. Text input mode can be entered by the append, insert, or change commands; it can be exited (and command mode re-entered) by typing a <period> ('.') alone at the beginning of a line.Initialization in ex and vi
The following symbols are used in this and following sections to specify locations in the edit buffer:- alternate and current pathnames
-
Two pathnames, named current and alternate, are maintained by the editor. Any ex commands that take filenames as arguments shall set them as follows:-
- 1.
-
If a
file
argument is specified to the
ex
edit,
ex,
or
recover
commands, or if an
ex
tag
command replaces the contents of the edit buffer.
-
- a.
- If the command replaces the contents of the edit buffer, the current pathname shall be set to the file argument or the file indicated by the tag, and the alternate pathname shall be set to the previous value of the current pathname.
- b.
- Otherwise, the alternate pathname shall be set to the file argument.
-
- 2.
-
If a
file
argument is specified to the
ex
next
command:
-
- a.
- If the command replaces the contents of the edit buffer, the current pathname shall be set to the first file argument, and the alternate pathname shall be set to the previous value of the current pathname.
-
- 3.
- If a file argument is specified to the ex file command, the current pathname shall be set to the file argument, and the alternate pathname shall be set to the previous value of the current pathname.
- 4.
-
If a
file
argument is specified to the
ex
read
and
write
commands (that is, when reading or writing a file, and not to the
program named by the
shell
edit option), or a
file
argument is specified to the
ex
xit
command:
-
- a.
- If the current pathname has no value, the current pathname shall be set to the file argument.
- b.
- Otherwise, the alternate pathname shall be set to the file argument.
-
-
- current line
-
The line of the edit buffer referenced by the cursor. Each command description specifies the current line after the command has been executed, as the current line value. When the edit buffer contains no lines, the current line shall be zero; see Addressing in ex. - current column
-
The current display line column occupied by the cursor. (The columns shall be numbered beginning at 1.) Each command description specifies the current column after the command has been executed, as the current column value. This column is an ideal column that is remembered over the lifetime of the editor. The actual display line column upon which the cursor rests may be different from the current column; see the cursor positioning discussion in Command Descriptions in vi. - set to non-<blank>
-
A description for a current column value, meaning that the current column shall be set to the last display line column on which is displayed any part of the first non-<blank> of the line. If the line has no non-<blank> non-<newline> characters, the current column shall be set to the last display line column on which is displayed any part of the last non-<newline> character in the line. If the line is empty, the current column shall be set to column position 1. The length of lines in the edit buffer may be limited to {LINE_MAX} bytes. In open and visual mode, the length of lines in the edit buffer may be limited to the number of characters that will fit in the display. If either limit is exceeded during editing, an error message shall be written. If either limit is exceeded by a line read in from a file, an error message shall be written and the edit session may be terminated. If the editor stops running due to any reason other than a user command, and the edit buffer has been modified since the last complete write, it shall be equivalent to a SIGHUP asynchronous event. If the system crashes, it shall be equivalent to a SIGHUP asynchronous event. During initialization (before the first file is copied into the edit buffer or any user commands from the terminal are processed) the following shall occur: - 1.
- If the environment variable EXINIT is set, the editor shall execute the ex commands contained in that variable.
- 2.
-
If the
EXINIT
variable is not set, and all of the following are true:
-
- a.
- The HOME environment variable is not null and not empty.
- b.
-
The file
.exrc
in the directory referred to by the
HOME
environment variable:
-
- i.
- Exists
- ii.
- Is owned by the same user ID as the real user ID of the process or the process has appropriate privileges
- iii.
- Is not writable by anyone other than the owner
-
-
- 3.
-
If and only if all of the following are true:
-
- a.
- The current directory is not referred to by the HOME environment variable.
- b.
- A command in the EXINIT environment variable or a command in the .exrc file in the directory referred to by the HOME environment variable sets the editor option exrc.
- c.
-
The
.exrc
file in the current directory:
-
- i.
- Exists
- ii.
- Is owned by the same user ID as the real user ID of the process, or by one of a set of implementation-defined user IDs
- iii.
- Is not writable by anyone other than the owner
-
-
- 1.
- If the user specified the -t option, the effect shall be as if the ex tag command was entered with the specified argument, with the exception that if tag processing does not result in a file to edit, the effect shall be as described in step 3. below.
- 2.
- Otherwise, if the user specified any command line file arguments, the effect shall be as if the ex edit command was entered with the first of those arguments as its file argument.
- 3.
- Otherwise, the effect shall be as if the ex edit command was entered with a nonexistent filename as its file argument. It is unspecified whether this action shall set the current pathname. In an implementation where this action does not set the current pathname, any editor command using the current pathname shall fail until an editor command sets the current pathname. If the -r option was specified, the first time a file in the initial argument list or a file specified by the -t option is edited, if recovery information has previously been saved about it, that information shall be recovered and the editor shall behave as if the contents of the edit buffer have already been modified. If there are multiple instances of the file to be recovered, the one most recently saved shall be recovered, and an informational message that there are previous versions of the file that can be recovered shall be written. If no recovery information about a file is available, an informational message to this effect shall be written, and the edit shall proceed as usual. If the -c option was specified, the first time a file that already exists (including a file that might not exist but for which recovery information is available, when the -r option is specified) replaces or initializes the contents of the edit buffer, the current line shall be set to the last line of the edit buffer, the current column shall be set to non-<blank>, and the ex commands specified with the -c option shall be executed. In this case, the current line and current column shall not be set as described for the command associated with the replacement or initialization of the edit buffer contents. However, if the -t option or a tag command is associated with this action, the -c option commands shall be executed and then the movement to the tag shall be performed. The current argument list shall initially be set to the filenames specified by the user on the command line. If no filenames are specified by the user, the current argument list shall be empty. If the -t option was specified, it is unspecified whether any filename resulting from tag processing shall be prepended to the current argument list. In the case where the filename is added as a prefix to the current argument list, the current argument list reference shall be set to that filename. In the case where the filename is not added as a prefix to the current argument list, the current argument list reference shall logically be located before the first of the filenames specified on the command line (for example, a subsequent ex next command shall edit the first filename from the command line). If the -t option was not specified, the current argument list reference shall be to the first of the filenames on the command line.
Addressing in ex
Addressing in ex relates to the current line and the current column; the address of a line is its 1-based line number, the address of a column is its 1-based count from the beginning of the line. Generally, the current line is the last line affected by a command. The current line number is the address of the current line. In each command description, the effect of the command on the current line number and the current column is described. Addresses are constructed as follows:- 1.
- The character '.' (period) shall address the current line.
- 2.
- The character '$' shall address the last line of the edit buffer.
- 3.
- The positive decimal number n shall address the nth line of the edit buffer.
- 4.
- The address dq'xdq refers to the line marked with the mark name character 'x', which shall be a lowercase letter from the portable character set, the backquote character, or the single-quote character. It shall be an error if the line that was marked is not currently present in the edit buffer or the mark has not been set. Lines can be marked with the ex mark or k commands, or the vi m command.
- 5.
- A regular expression enclosed by <slash> characters ('/') shall address the first line found by searching forwards from the line following the current line toward the end of the edit buffer and stopping at the first line for which the line excluding the terminating <newline> matches the regular expression. As stated in Regular Expressions in ex, an address consisting of a null regular expression delimited by <slash> characters (dq//dq) shall address the next line for which the line excluding the terminating <newline> matches the last regular expression encountered. In addition, the second <slash> can be omitted at the end of a command line. If the wrapscan edit option is set, the search shall wrap around to the beginning of the edit buffer and continue up to and including the current line, so that the entire edit buffer is searched. Within the regular expression, the sequence dq\/dq shall represent a literal <slash> instead of the regular expression delimiter.
- 6.
- A regular expression enclosed in <question-mark> characters ('?') shall address the first line found by searching backwards from the line preceding the current line toward the beginning of the edit buffer and stopping at the first line for which the line excluding the terminating <newline> matches the regular expression. An address consisting of a null regular expression delimited by <question-mark> characters (dq??dq) shall address the previous line for which the line excluding the terminating <newline> matches the last regular expression encountered. In addition, the second <question-mark> can be omitted at the end of a command line. If the wrapscan edit option is set, the search shall wrap around from the beginning of the edit buffer to the end of the edit buffer and continue up to and including the current line, so that the entire edit buffer is searched. Within the regular expression, the sequence dq\?dq shall represent a literal <question-mark> instead of the RE delimiter.
- 7.
- A <plus-sign> ('+') or a minus-sign ('-') followed by a decimal number shall address the current line plus or minus the number. A '+' or '-' not followed by a decimal number shall address the current line plus or minus 1. Addresses can be followed by zero or more address offsets, optionally <blank>-separated. Address offsets are constructed as follows:
- 1.
- A '+' or '-' immediately followed by a decimal number shall add (subtract) the indicated number of lines to (from) the address. A '+' or '-' not followed by a decimal number shall add (subtract) 1 to (from) the address.
- 2.
- A decimal number shall add the indicated number of lines to the address. It shall not be an error for an intermediate address value to be less than zero or greater than the last line in the edit buffer. It shall be an error for the final address value to be less than zero or greater than the last line in the edit buffer. Commands take zero, one, or two addresses; see the descriptions of 1addr and 2addr in Command Descriptions in ex. If more than the required number of addresses are provided to a command that requires zero addresses, it shall be an error. Otherwise, if more than the required number of addresses are provided to a command, the addresses specified first shall be evaluated and then discarded until the maximum number of valid addresses remain. Addresses shall be separated from each other by a <comma> (',') or a <semicolon> (';'). If no address is specified before or after a <comma> or <semicolon> separator, it shall be as if the address of the current line was specified before or after the separator. In the case of a <semicolon> separator, the current line ('.') shall be set to the first address, and only then will the next address be calculated. This feature can be used to determine the starting line for forwards and backwards searches (see rules 5. and 6.). A <percent-sign> ('%') shall be equivalent to entering the two addresses dq1,$dq. Any delimiting <blank> characters between addresses, address separators, or address offsets shall be discarded.
Command Line Parsing in ex
The following symbol is used in this and following sections to describe parsing behavior:- escape
- If a character is referred to as ``<backslash>-escaped'' or ``<control>-V-escaped'', it shall mean that the character acquired or lost a special meaning by virtue of being preceded, respectively, by a <backslash> or <control>-V character. Unless otherwise specified, the escaping character shall be discarded at that time and shall not be further considered for any purpose. Command-line parsing shall be done in the following steps. For each step, characters already evaluated shall be ignored; that is, the phrase ``leading character'' refers to the next character that has not yet been evaluated.
- 1.
- Leading <colon> characters shall be skipped.
- 2.
- Leading <blank> characters shall be skipped.
- 3.
- If the leading character is a double-quote character, the characters up to and including the next non-<backslash>-escaped <newline> shall be discarded, and any subsequent characters shall be parsed as a separate command.
- 4.
- Leading characters that can be interpreted as addresses shall be evaluated; see Addressing in ex.
- 5.
- Leading <blank> characters shall be skipped.
- 6.
-
If the next character is a
<vertical-line>
character or a
<newline>:
-
- a.
-
If the next character is a
<newline>:
-
- i.
- If ex is in open or visual mode, the current line shall be set to the last address specified, if any.
- ii.
- Otherwise, if the last command was terminated by a <vertical-line> character, no action shall be taken; for example, the command dq||<newline>dq shall execute two implied commands, not three.
- iii.
- Otherwise, step 6.b. shall apply.
-
- b.
-
Otherwise, the implied command shall be the
print
command. The last
#,
p,
and
l
flags specified to any
ex
command shall be remembered and shall apply to this implied command.
Executing the
ex
number,
print,
or
list
command shall set the remembered flags to
#,
nothing, and
l,
respectively, plus any other flags specified for that execution of the
number,
print,
or
list
command.
-
If ex is not currently performing a global or v command, and no address or count is specified, the current line shall be incremented by 1 before the command is executed. If incrementing the current line would result in an address past the last line in the edit buffer, the command shall fail, and the increment shall not happen.
-
- c.
- The <newline> or <vertical-line> character shall be discarded and any subsequent characters shall be parsed as a separate command.
-
- 7.
-
The command name shall be comprised of the next character (if the
character is not alphabetic), or the next character and any subsequent
alphabetic characters (if the character is alphabetic), with the
following exceptions:
-
- a.
- Commands that consist of any prefix of the characters in the command name delete, followed immediately by any of the characters 'l', 'p', '+', '-', or '#' shall be interpreted as a delete command, followed by a <blank>, followed by the characters that were not part of the prefix of the delete command. The maximum number of characters shall be matched to the command name delete; for example, dqdeldq shall not be treated as dqdedq followed by the flag l.
- b.
- Commands that consist of the character 'k', followed by a character that can be used as the name of a mark, shall be equivalent to the mark command followed by a <blank>, followed by the character that followed the 'k'.
- c.
- Commands that consist of the character 's', followed by characters that could be interpreted as valid options to the s command, shall be the equivalent of the s command, without any pattern or replacement values, followed by a <blank>, followed by the characters after the 's'.
-
- 8.
-
The command name shall be matched against the possible command names,
and a command name that contains a prefix matching the characters
specified by the user shall be the executed command. In the case of
commands where the characters specified by the user could be ambiguous,
the executed command shall be as follows:
a append n next t t c change p print u undo ch change pr print un undo e edit r read v v m move re read w write ma mark s s -
Implementation extensions with names causing similar ambiguities shall not be checked for a match until all possible matches for commands specified by POSIX.1-2008 have been checked.
-
- 9.
- If the command is a ! command, or if the command is a read command followed by zero or more <blank> characters and a !, or if the command is a write command followed by one or more <blank> characters and a !, the rest of the command shall include all characters up to a non-<backslash>-escaped <newline>. The <newline> shall be discarded and any subsequent characters shall be parsed as a separate ex command.
- 10.
-
Otherwise, if the command is an
edit,
ex,
or
next
command, or a
visual
command while in open or visual mode, the next part of the command
shall be parsed as follows:
-
- a.
- Any '!' character immediately following the command shall be skipped and be part of the command.
- b.
- Any leading <blank> characters shall be skipped and be part of the command.
- c.
- If the next character is a '+', characters up to the first non-<backslash>-escaped <newline> or non-<backslash>-escaped <blank> shall be skipped and be part of the command.
- d.
- The rest of the command shall be determined by the steps specified in paragraph 12.
-
- 11.
-
Otherwise, if the command is a
global,
open,
s,
or
v
command, the next part of the command shall be parsed as follows:
-
- a.
- Any leading <blank> characters shall be skipped and be part of the command.
- b.
-
If the next character is not an alphanumeric, double-quote,
<newline>,
<backslash>,
or
<vertical-line>
character:
-
- i.
- The next character shall be used as a command delimiter.
- ii.
- If the command is a global, open, or v command, characters up to the first non-<backslash>-escaped <newline>, or first non-<backslash>-escaped delimiter character, shall be skipped and be part of the command.
- iii.
- If the command is an s command, characters up to the first non-<backslash>-escaped <newline>, or second non-<backslash>-escaped delimiter character, shall be skipped and be part of the command.
-
- c.
- If the command is a global or v command, characters up to the first non-<backslash>-escaped <newline> shall be skipped and be part of the command.
- d.
- Otherwise, the rest of the command shall be determined by the steps specified in paragraph 12.
-
- 12.
-
Otherwise:
-
- a.
- If the command was a map, unmap, abbreviate, or unabbreviate command, characters up to the first non-<control>-V-escaped <newline>, <vertical-line>, or double-quote character shall be skipped and be part of the command.
- b.
- Otherwise, characters up to the first non-<backslash>-escaped <newline>, <vertical-line>, or double-quote character shall be skipped and be part of the command.
- c.
- If the command was an append, change, or insert command, and the step 12.b. ended at a <vertical-line> character, any subsequent characters, up to the next non-<backslash>-escaped <newline> shall be used as input text to the command.
- d.
- If the command was ended by a double-quote character, all subsequent characters, up to the next non-<backslash>-escaped <newline>, shall be discarded.
- e.
- The terminating <newline> or <vertical-line> character shall be discarded and any subsequent characters shall be parsed as a separate ex command.
-
- *
- An informational message to this effect shall be written. Execution of the ex command shall stop, and the cursor (for example, the current line and column) shall not be further modified.
- *
- If the ex command resulted from a map expansion, all characters from that map expansion shall be discarded, except as otherwise specified by the map command.
- *
- Otherwise, if the ex command resulted from the processing of an EXINIT environment variable, a .exrc file, a :source command, a -c option, or a +command specified to an ex edit, ex, next, or visual command, no further commands from the source of the commands shall be executed.
- *
- Otherwise, if the ex command resulted from the execution of a buffer or a global or v command, no further commands caused by the execution of the buffer or the global or v command shall be executed.
- *
- Otherwise, if the ex command was not terminated by a <newline>, all characters up to and including the next non-<backslash>-escaped <newline> shall be discarded.
Input Editing in ex
The following symbol is used in this and the following sections to specify command actions:- word
-
In the POSIX locale, a word consists of a maximal sequence of letters,
digits, and underscores, delimited at both ends by characters other
than letters, digits, or underscores, or by the beginning or end of a
line or the edit buffer.
When accepting input characters from the user, in either
ex
command mode or
ex
text input mode,
ex
shall enable canonical mode input processing, as defined in the System Interfaces volume of POSIX.1-2008.
If in ex text input mode: - 1.
- If the number edit option is set, ex shall prompt for input using the line number that would be assigned to the line if it is entered, in the format specified for the ex number command.
- 2.
- If the autoindent edit option is set, ex shall prompt for input using autoindent characters, as described by the autoindent edit option. autoindent characters shall follow the line number, if any. If in ex command mode:
- 1.
- If the prompt edit option is set, input shall be prompted for using a single ':' character; otherwise, there shall be no prompt. The input characters in the following sections shall have the following effects on the input line.
Scroll
- Synopsis:
-
-
-
eof
-
- If the eof character is the first character entered on the line, the line shall be evaluated as if it contained two characters: a <control>-D and a <newline>. Otherwise, the eof character shall have no special meaning.
If in ex text input mode:- If the cursor follows an autoindent character, the autoindent characters in the line shall be modified so that a part of the next text input character will be displayed on the first column in the line after the previous shiftwidth edit option column boundary, and the user shall be prompted again for input for the same line. Otherwise, if the cursor follows a '0', which follows an autoindent character, and the '0' was the previous text input character, the '0' and all autoindent characters in the line shall be discarded, and the user shall be prompted again for input for the same line. Otherwise, if the cursor follows a '^', which follows an autoindent character, and the '^' was the previous text input character, the '^' and all autoindent characters in the line shall be discarded, and the user shall be prompted again for input for the same line. In addition, the autoindent level for the next input line shall be derived from the same line from which the autoindent level for the current input line was derived. Otherwise, if there are no autoindent or text input characters in the line, the eof character shall be discarded. Otherwise, the eof character shall have no special meaning.
-
<newline>
- Synopsis:
-
-
-
<newline>
<control>-J
-
- Cause the command line to be parsed; <control>-J shall be mapped to the <newline> for this purpose.
If in ex text input mode:- Terminate the current line. If there are no characters other than autoindent characters on the line, all characters on the line shall be discarded. Prompt for text input on a new line after the current line. If the autoindent edit option is set, an appropriate number of autoindent characters shall be added as a prefix to the line as described by the ex autoindent edit option.
-
<backslash>
- Synopsis:
-
-
-
<backslash>
-
-
<control>-V
- Synopsis:
-
-
-
<control>-V
-
-
<control>-W
- Synopsis:
-
-
-
<control>-W
-
-
Command Descriptions in ex
The following symbols are used in this section to represent command modifiers. Some of these modifiers can be omitted, in which case the specified defaults shall be used.- 1addr
-
A single line address, given in any of the forms described in
Addressing in ex;
the default shall be the current line ('.'),
unless otherwise specified.
-
If the line address is zero, it shall be an error, unless otherwise specified in the following command descriptions. If the edit buffer is empty, and the address is specified with a command other than =, append, insert, open, put, read, or visual, or the address is not zero, it shall be an error.
-
- 2addr
-
Two addresses specifying an inclusive range of lines. If no addresses
are specified, the default for
2addr
shall be the current line only (dq.,.dq),
unless otherwise specified in the following command descriptions. If
one address is specified,
2addr
shall specify that line only, unless otherwise specified in the
following command descriptions.
-
It shall be an error if the first address is greater than the second address. If the edit buffer is empty, and the two addresses are specified with a command other than the !, write, wq, or xit commands, or either address is not zero, it shall be an error.
-
- count
-
A positive decimal number. If
count
is specified, it shall be equivalent to specifying an additional
address to the command, unless otherwise specified by the following
command descriptions. The additional address shall be equal to the last
address specified to the command (either explicitly or by default) plus
count-1.
-
If this would result in an address greater than the last line of the edit buffer, it shall be corrected to equal the last line of the edit buffer.
-
- flags
-
One or more of the characters
'+',
'-',
'#',
'p',
or
'l'
(ell). The flag characters can be
<blank>-separated,
and in any order or combination. The characters
'#',
'p',
and
'l'
shall cause lines to be written in the format specified by the
print
command with the specified
flags.
-
The lines to be written are as follows:- 1.
- All edit buffer lines written during the execution of the ex &, ~, list, number, open, print, s, visual, and z commands shall be written as specified by flags.
- 2.
- After the completion of an ex command with a flag as an argument, the current line shall be written as specified by flags, unless the current line was the last line written by the command. The characters '+' and '-' cause the value of the current line after the execution of the ex command to be adjusted by the offset address as described in Addressing in ex. This adjustment shall occur before the current line is written as described in 2. above. The default for flags shall be none.
-
- buffer
-
One of a number of named areas for holding text. The named buffers are
specified by the alphanumeric characters of the POSIX locale. There
shall also be one ``unnamed'' buffer. When no buffer is specified for
editor commands that use a buffer, the unnamed buffer shall be used.
Commands that store text into buffers shall store the text as it was
before the command took effect, and shall store text occurring earlier
in the file before text occurring later in the file, regardless of how
the text region was specified. Commands that store text into buffers
shall store the text into the unnamed buffer as well as any specified
buffer.
-
In ex commands, buffer names are specified as the name by itself. In open or visual mode commands the name is preceded by a double-quote ('' ) character. If the specified buffer name is an uppercase character, and the buffer contents are to be modified, the buffer shall be appended to rather than being overwritten. If the buffer is not being modified, specifying the buffer name in lowercase and uppercase shall have identical results. There shall also be buffers named by the numbers 1 through 9. In open and visual mode, if a region of text including characters from more than a single line is being modified by the vi c or d commands, the motion character associated with the c or d commands specifies that the buffer text shall be in line mode, or the commands %, `, /, ?, (, ), N, n, {, or } are used to define a region of text for the c or d commands, the contents of buffers 1 through 8 shall be moved into the buffer named by the next numerically greater value, the contents of buffer 9 shall be discarded, and the region of text shall be copied into buffer 1. This shall be in addition to copying the text into a user-specified buffer or unnamed buffer, or both. Numeric buffers can be specified as a source buffer for open and visual mode commands; however, specifying a numeric buffer as the write target of an open or visual mode command shall have unspecified results. The text of each buffer shall have the characteristic of being in either line or character mode. Appending text to a non-empty buffer shall set the mode to match the characteristic of the text being appended. Appending text to a buffer shall cause the creation of at least one additional line in the buffer. All text stored into buffers by ex commands shall be in line mode. The ex commands that use buffers as the source of text specify individually how buffers of different modes are handled. Each open or visual mode command that uses buffers for any purpose specifies individually the mode of the text stored into the buffer and how buffers of different modes are handled.
-
- file
-
Command text used to derive a pathname. The default shall be the
current pathname, as defined previously, in which case, if no current
pathname has yet been established it shall be an error, except where
specifically noted in the individual command descriptions that follow.
If the command text contains any of the characters
'~',
'{',
'[',
'*',
'?',
'$',
'' ,
backquote, single-quote, and
<backslash>,
it shall be subjected to the process of ``shell expansions'', as
described below; if more than a single pathname results and the
command expects only one, it shall be an error.
-
The process of shell expansions in the editor shall be done as follows. The ex utility shall pass two arguments to the program named by the shell edit option; the first shall be -c, and the second shall be the string dqechodq and the command text as a single argument. The standard output and standard error of that command shall replace the command text.
-
- !
- A character that can be appended to the command name to modify its operation, as detailed in the individual command descriptions. With the exception of the ex read, write, and ! commands, the '!' character shall only act as a modifier if there are no <blank> characters between it and the command name.
- remembered search direction
-
The vi commands N and n begin searching in a forwards or backwards direction in the edit buffer based on a remembered search direction, which is initially unset, and is set by the ex global, v, s, and tag commands, and the vi / and ? commands.
Abbreviate
- Synopsis:
-
-
-
ab[breviate][lhs rhs]
-
-
- 1.
- If there are no characters inserted before the word and non-word or <ESC> characters that triggered the check, the set of characters shall consist of the word character.
- 2.
- If the character inserted before the word and non-word or <ESC> characters that triggered the check is a word character, the set of characters shall consist of the characters inserted immediately before the triggering characters that are word characters, plus the triggering word character.
- 3.
- If the character inserted before the word and non-word or <ESC> characters that triggered the check is not a word character, the set of characters shall consist of the characters that were inserted before the triggering characters that are neither <blank> characters nor word characters, plus the triggering word character. It is unspecified whether the lhs argument entered for the ex abbreviate and unabbreviate commands is replaced in this fashion. Regardless of whether or not the replacement occurs, the effect of the command shall be as if the replacement had not occurred. Current line: Unchanged. Current column: Unchanged.
Append
- Synopsis:
-
-
-
[1addr] a[ppend][!]
-
-
Arguments
- Synopsis:
-
-
-
ar[gs]
-
-
Change
- Synopsis:
-
-
-
[2addr] c[hange][!][count]
-
-
Change Directory
- Synopsis:
-
-
-
chd[ir][!][directory] cd[!][directory]
-
-
Copy
- Synopsis:
-
-
-
[2addr] co[py] 1addr [flags] [2addr] t 1addr [flags]
-
-
Delete
- Synopsis:
-
-
-
[2addr] d[elete][buffer][count][flags]
-
-
Edit
- Synopsis:
-
-
-
e[dit][!][+command][file] ex[!][+command][file]
-
Otherwise: Current line: Set to the first line of the edit buffer. Current column: Set to non-<blank>. -
File
- Synopsis:
-
-
-
f[ile][file]
-
-
Global
- Synopsis:
-
-
-
[2addr] g[lobal] /pattern/ [commands] [2addr] v /pattern/ [commands]
-
-
- 1.
- If in ex command mode, it shall be as if the print command were specified.
- 2.
- Otherwise, no command shall be executed. For the append, change, and insert commands, the input text shall be included as part of the command, and the terminating <period> can be omitted if the command ends the list of commands. The open and visual commands can be specified as one of the commands, in which case each marked line shall cause the editor to enter open or visual mode. If open or visual mode is exited using the vi Q command, the current line shall be set to the next marked line, and open or visual mode reentered, until the list of marked lines is exhausted. The global, v, and undo commands cannot be used in commands. Marked lines may be deleted by commands executed for lines occurring earlier in the file than the marked lines. In this case, no commands shall be executed for the deleted lines. If the remembered search direction is not set, the global and v commands shall set it to forward. The autoprint and autoindent edit options shall be inhibited for the duration of the g or v command. Current line: If no commands executed, set to the last marked line. Otherwise, as specified for the executed ex commands. Current column: If no commands are executed, set to non-<blank>; otherwise, as specified for the individual ex commands.
Insert
- Synopsis:
-
-
-
[1addr] i[nsert][!]
-
-
Join
- Synopsis:
-
-
-
[2addr] j[oin][!][count][flags]
-
- If no address was specified, the join command shall behave as if 2addr were the current line and the current line plus count (.,. + count). If one address was specified, the join command shall behave as if 2addr were the specified address and the specified address plus count (addr,addr + count). If two addresses were specified, the join command shall behave as if an additional address, equal to the last address plus count -1 (addr1,addr2,addr2 + count -1), was specified. If this would result in a second address greater than the last line of the edit buffer, it shall be corrected to be equal to the last line of the edit buffer.
- If no address was specified, the join command shall behave as if 2addr were the current line and the next line (.,. +1). If one address was specified, the join command shall behave as if 2addr were the specified address and the next line (addr,addr +1).
-
- 1.
- Discard leading <space> characters from the line to be joined.
- 2.
- If the line to be joined is now empty, delete it, and skip steps 3 through 5.
- 3.
- If the current line ends in a <blank>, or the first character of the line to be joined is a ')' character, join the lines without further modification.
- 4.
- If the last character of the current line is a '.', join the lines with two <space> characters between them.
- 5.
- Otherwise, join the lines with a single <space> between them. Current line: Set to the first line specified. Current column: Set to non-<blank>.
List
- Synopsis:
-
-
-
[2addr] l[ist][count][flags]
-
-
[2addr] p[rint][count] l[flags]
-
Map
- Synopsis:
-
-
-
map[!][lhs rhs]
-
-
- 1.
- If '!' is specified, write the current list of text input mode maps.
- 2.
- Otherwise, write the current list of command mode maps.
- 3.
-
Do nothing more.
Implementations may restrict the set of characters accepted in
lhs
or
rhs,
except that printable characters and
<blank>
characters shall not be restricted. Additional restrictions shall be
implementation-defined. In both
lhs
and
rhs,
any character can be escaped with a
<control>-V,
in which case the character shall not be used to delimit
lhs
from
rhs,
and the escaping
<control>-V
shall be discarded.
If the character
'!'
is appended to the
map
command name, the mapping shall be effective during open or visual text
input mode rather than
open
or
visual
command mode. This allows
lhs
to have two different
map
definitions at the same time: one for command mode and one for text
input mode.
For command mode mappings:- When the lhs is entered as any part of a vi command in open or visual mode (but not as part of the arguments to the command), the action shall be as if the corresponding rhs had been entered. If any character in the command, other than the first, is escaped using a <control>-V character, that character shall not be part of a match to an lhs. It is unspecified whether implementations shall support map commands where the lhs is more than a single character in length, where the first character of the lhs is printable.
- If lhs contains more than one character and the first character is '#', followed by a sequence of digits corresponding to a numbered function key, then when this function key is typed it shall be mapped to rhs. Characters other than digits following a '#' character also represent the function key named by the characters in the lhs following the '#' and may be mapped to rhs. It is unspecified how function keys are named or what function keys are supported.
- When the lhs is entered as any part of text entered in open or visual text input modes, the action shall be as if the corresponding rhs had been entered. If any character in the input text is escaped using a <control>-V character, that character shall not be part of a match to an lhs. It is unspecified whether the lhs text entered for subsequent map or unmap commands is replaced with the rhs text for the purposes of the screen display; regardless of whether or not the display appears as if the corresponding rhs text was entered, the effect of the command shall be as if the lhs text was entered.
Mark
- Synopsis:
-
-
-
[1addr] ma[rk] character [1addr] k character
-
-
- 1.
- The use of '$' as an ex address
- 2.
- The use of a positive decimal number as an ex address
- 3.
- The use of a search command as an ex address
- 4.
- The use of a mark reference as an ex address
- 5.
- The use of the following open and visual mode commands: <control>-], %, (, ), [, ], {, }
- 6.
- The use of the following open and visual mode commands: ', G, H, L, M, z if the current line will change as a result of the command
- 7.
- The use of the open and visual mode commands: /, ?, N, `, n if the current line or column will change as a result of the command
- 8.
- The use of the ex mode commands: z, undo, global, v For rules 1., 2., 3., and 4., the ` and ' marks shall not be set if the ex command is parsed as specified by rule 6.a. in Command Line Parsing in ex. For rules 5., 6., and 7., the ` and ' marks shall not be set if the commands are used as motion commands in open and visual mode. For rules 1., 2., 3., 4., 5., 6., 7., and 8., the ` and ' marks shall not be set if the command fails. The ` and ' marks shall be set as described previously, each time the contents of the edit buffer are replaced (including the editing of the initial buffer), if in open or visual mode, or if in ex mode and the edit buffer is not empty, before any commands or movements (including commands or movements specified by the -c or -t options or the +command argument) are executed on the edit buffer. If in open or visual mode, the marks shall be set as if executing the vi m command; otherwise, as if executing the ex mark command. When changing from ex mode to open or visual mode, if the ` and ' marks are not already set, the ` and ' marks shall be set as described previously. Current line: Unchanged. Current column: Unchanged.
Move
- Synopsis:
-
-
-
[2addr] m[ove] 1addr [flags]
-
-
Next
- Synopsis:
-
-
-
n[ext][!][+command][file ...]
-
If one or more files is specified: -
- 1.
- Set the argument list to the specified filenames.
- 2.
- Set the current argument list reference to be the first entry in the argument list.
- 3.
- Set the current pathname to the first filename specified. Otherwise:
- 1.
- It shall be an error if there are no more filenames in the argument list after the filename currently referenced.
- 2.
- Set the current pathname and the current argument list reference to the filename after the filename currently referenced in the argument list. Replace the contents of the edit buffer with the contents of the file named by the current pathname. If for any reason the contents of the file cannot be accessed, the edit buffer shall be empty. This command shall be affected by the autowrite and writeany edit options. The +command option shall be <blank>-delimited; <blank> characters can be escaped by preceding them with a <backslash> character. The +command shall be interpreted as an ex command immediately after the contents of the edit buffer have been replaced and the current line and column have been set. Current line: Set as described for the edit command. Current column: Set as described for the edit command.
Number
- Synopsis:
-
-
-
[2addr] nu[mber][count][flags] [2addr] #[count][flags]
-
-
[2addr] p[rint][count] #[flags]
-
Open
- Synopsis:
-
-
-
[1addr] o[pen] /pattern/ [flags]
-
-
Preserve
- Synopsis:
-
-
-
pre[serve]
-
-
- Synopsis:
-
-
-
[2addr] p[rint][count][flags]
-
-
"%6d ", <line number>
-
- 1.
- The characters listed in the Base Definitions volume of POSIX.1-2008, Table 5-1, Escape Sequences and Associated Actions shall be written as the corresponding escape sequence.
- 2.
- Non-printable characters not in the Base Definitions volume of POSIX.1-2008, Table 5-1, Escape Sequences and Associated Actions shall be written as one three-digit octal number (with a preceding <backslash>) for each byte in the character (most significant byte first).
- 3.
- The end of each line shall be marked with a '$', and literal '$' characters within the line shall be written with a preceding <backslash>. Long lines shall be folded; the length at which folding occurs is unspecified, but should be appropriate for the output terminal, considering the number of columns of the terminal. If a line is folded, and the l flag is not specified and the list edit option is not set, it is unspecified whether a multi-column character at the folding position is separated; it shall not be discarded. Current line: Set to the last written line. Current column: Unchanged if the current line is unchanged; otherwise, set to non-<blank>.
Put
- Synopsis:
-
-
-
[1addr] pu[t][buffer]
-
-
Quit
- Synopsis:
-
-
-
q[uit][!]
-
-
- 1.
- If the edit buffer has been modified since the last complete write, it shall be an error.
- 2.
- If there are filenames in the argument list after the filename currently referenced, and the last command was not a quit, wq, xit, or ZZ (see Exit) command, it shall be an error. Otherwise, terminate the editing session.
Read
- Synopsis:
-
-
-
[1addr] r[ead][!][file]
-
-
Recover
- Synopsis:
-
-
-
rec[over][!] file
-
-
Rewind
- Synopsis:
-
-
-
rew[ind][!]
-
-
Set
- Synopsis:
-
-
-
se[t][option[=[value]] ...][nooption ...][option? ...][all]
-
-
Shell
- Synopsis:
-
-
-
sh[ell]
-
-
Source
- Synopsis:
-
-
-
so[urce] file
-
-
Substitute
- Synopsis:
-
-
-
[2addr] s[ubstitute][/pattern/repl/[options][count][flags]]
[2addr] &[options][count][flags]]
[2addr] ~[options][count][flags]]
-
-
s/pattern/repl/
-
s/pattern/repl/
-
Suspend
- Synopsis:
-
-
-
su[spend][!] st[op][!]
-
-
Tag
- Synopsis:
-
-
-
ta[g][!] tagstring
-
-
Unabbreviate
- Synopsis:
-
-
-
una[bbrev] lhs
-
-
Undo
- Synopsis:
-
-
-
u[ndo]
-
-
- 1.
- If lines are added or changed in the file, set to the first line added or changed.
- 2.
- Set to the line before the first line deleted, if it exists.
- 3.
- Set to 1 if the edit buffer is not empty.
- 4.
- Set to zero. Current column: Set to non-<blank>.
Unmap
- Synopsis:
-
-
-
unm[ap][!] lhs
-
-
Version
- Synopsis:
-
-
-
ve[rsion]
-
-
Visual
- Synopsis:
-
-
-
[1addr] vi[sual][type][count][flags]
-
-
- +
- Place the beginning of the specified line at the top of the display.
- -
- Place the end of the specified line at the bottom of the display.
- .
- Place the beginning of the specified line in the middle of the display.
- ^
- If the specified line is less than or equal to the value of the window edit option, set the line to 1; otherwise, decrement the line by the value of the window edit option minus 1. Place the beginning of this line as close to the bottom of the displayed lines as possible, while still displaying the value of the window edit option number of lines. Current line: Set to the specified line. Current column: Set to non-<blank>.
Write
- Synopsis:
-
-
-
[2addr] w[rite][!][>>][file] [2addr] w[rite][!][file] [2addr] wq[!][>>][file]
-
-
- 1.
- If the >> argument is specified, and the file already exists, the lines shall be appended to the file instead of replacing its contents. If the >> argument is specified, and the file does not already exist, it is unspecified whether the write shall proceed as if the >> argument had not been specified or if the write shall fail.
- 2.
- If the readonly edit option is set (see readonly), the write shall fail.
- 3.
- If file is specified, and is not the current pathname, and the file exists, the write shall fail.
- 4.
- If file is not specified, the current pathname shall be used. If there is no current pathname, the write command shall fail.
- 5.
- If the current pathname is used, and the current pathname has been changed by the file or read commands, and the file exists, the write shall fail. If the write is successful, subsequent writes shall not fail for this reason (unless the current pathname is changed again).
- 6.
- If the whole edit buffer is not being written, and the file to be written exists, the write shall fail. For rules 1., 2., 3., and 5., the write can be forced by appending the character '!' to the command name. For rules 2., 3., and 5., the write can be forced by setting the writeany edit option. Additional, implementation-defined tests may cause the write to fail. If the edit buffer is empty, a file without any contents shall be written. An informational message shall be written noting the number of lines and bytes written. Otherwise, if the command is followed by one or more <blank> characters, and the file is preceded by '!', the rest of the line after the '!' shall have '%', '#', and '!' characters expanded as described in Command Line Parsing in ex. The ex utility shall then pass two arguments to the program named by the shell edit option; the first shall be -c and the second shall be the expanded arguments to the write command as a single argument. The specified lines shall be written to the standard input of the command. The standard error and standard output of the program, if any, shall be written as described for the print command. If the last character in that output is not a <newline>, a <newline> shall be written at the end of the output. The special meaning of the '!' following the write command can be overridden by escaping it with a <backslash> character. Current line: Unchanged. Current column: Unchanged.
Write and Exit
- Synopsis:
-
-
-
[2addr] x[it][!][file]
-
-
Yank
- Synopsis:
-
-
-
[2addr] ya[nk][buffer][count]
-
-
Adjust Window
- Synopsis:
-
-
-
[1addr] z[!][type ...][count][flags]
-
-
- -
-
The specified line shall be decremented by the following value:
-
-
(((number of ``-'' characters) x count) -1)
-
-
- +
-
The specified line shall be incremented by the following value:
-
-
(((number of ``+'' characters) -1) x count) +1
-
-
- =,.
-
If more than a single
'.'
or
'='
is specified, it shall be an error. The following steps shall be
taken:
-
- 1.
- If count is zero, nothing shall be written.
- 2.
-
Write as many of the
N
lines before the current line in the edit buffer as exist. If
count
or
'!'
was specified,
N
shall be:
-
-
(count -1) /2
-
(count -3) /2
-
-
- 3.
- If '=' was specified as the type character, write a line consisting of the smaller of the number of columns in the display divided by two, or 40 '-' characters.
- 4.
- Write the current line.
- 5.
- Repeat step 3.
- 6.
- Write as many of the N lines after the current line in the edit buffer as exist. N shall be defined as in step 2. If N is a number less than 3, no lines shall be written. If count is less than 3, no lines shall be written.
-
- ^
-
The specified line shall be decremented by the following value:
-
-
(((number of ``^'' characters) +1) x count) -1
-
-
Escape
- Synopsis:
-
-
-
! command [addr]! command
-
Current line: -
- 1.
- If no lines are specified, unchanged.
- 2.
- Otherwise, set to the last line read in, if any lines are read in.
- 3.
- Otherwise, set to the line before the first line of the lines specified, if that line exists.
- 4.
- Otherwise, set to the first line of the edit buffer if the edit buffer is not empty.
- 5.
- Otherwise, set to zero. Current column: If no lines are specified, unchanged. Otherwise, set to non-<blank>.
Shift Left
- Synopsis:
-
-
-
[2addr] <[< ...][count][flags]
-
-
Shift Right
- Synopsis:
-
-
-
[2addr] >[> ...][count][flags]
-
-
<control>-D
- Synopsis:
-
-
-
<control>-D
-
-
Write Line Number
- Synopsis:
-
-
-
[1addr] = [flags]
-
-
Execute
- Synopsis:
-
-
-
[2addr] @ buffer [2addr] * buffer
-
-
Regular Expressions in ex
The ex utility shall support regular expressions that are a superset of the basic regular expressions described in the Base Definitions volume of POSIX.1-2008, Section 9.3, Basic Regular Expressions. A null regular expression (dq//dq) shall be equivalent to the last regular expression encountered. Regular expressions can be used in addresses to specify lines and, in some commands (for example, the substitute command), to specify portions of a line to be substituted. The following constructs can be used to enhance the basic regular expressions:- \<
- Match the beginning of a word. (See the definition of word at the beginning of Command Descriptions in ex.)
- \>
- Match the end of a word.
- ~
- Match the replacement part of the last substitute command. The <tilde> ('~') character can be escaped in a regular expression to become a normal character with no special meaning. The <backslash> shall be discarded. When the editor option magic is not set, the only characters with special meanings shall be '^' at the beginning of a pattern, '$' at the end of a pattern, and <backslash>. The characters '.', '*', '[', and '~' shall be treated as ordinary characters unless preceded by a <backslash>; when preceded by a <backslash> they shall regain their special meaning, or in the case of <backslash>, be handled as a single <backslash>. <backslash> characters used to escape other characters shall be discarded.
Replacement Strings in ex
The character '&' ('\&' if the editor option magic is not set) in the replacement string shall stand for the text matched by the pattern to be replaced. The character '~' ('\~' if magic is not set) shall be replaced by the replacement part of the previous substitute command. The sequence '\n', where n is an integer, shall be replaced by the text matched by the corresponding back-reference expression. If the corresponding back-reference expression does not match, then the characters '\n' shall be replaced by the empty string. The strings '\l', '\u', '\L', and '\U' can be used to modify the case of elements in the replacement string (using the '\&' or dq\dqdigit) notation. The string '\l' ('\u') shall cause the character that follows to be converted to lowercase (uppercase). The string '\L' ('\U') shall cause all characters subsequent to it to be converted to lowercase (uppercase) as they are inserted by the substitution until the string '\e' or '\E', or the end of the replacement string, is encountered. Otherwise, any character following a <backslash> shall be treated as that literal character, and the escaping <backslash> shall be discarded. An example of case conversion with the s command is as follows:
-
:p The cat sat on the mat. :s/\<.at\>/\u&/gp The Cat Sat on the Mat. :s/S\(.*\)M/S\U\1\eM/p The Cat SAT ON THE Mat.
Edit Options in ex
The ex utility has a number of options that modify its behavior. These options have default settings, which can be changed using the set command. Options are Boolean unless otherwise specified.autoindent, ai
[Default unset] If autoindent is set, each line in input mode shall be indented (using first as many <tab> characters as possible, as determined by the editor option tabstop, and then using <space> characters) to align with another line, as follows:- 1.
- If in open or visual mode and the text input is part of a line-oriented command (see the EXTENDED DESCRIPTION in vi), align to the first column.
- 2.
-
Otherwise, if in open or visual mode, indentation for each line shall
be set as follows:
-
- a.
- If a line was previously inserted as part of this command, it shall be set to the indentation of the last inserted line by default, or as otherwise specified for the <control>-D character in Input Mode Commands in vi.
- b.
- Otherwise, it shall be set to the indentation of the previous current line, if any; otherwise, to the first column.
-
- 3.
-
For the
ex
a,
i,
and
c
commands, indentation for each line shall be set as follows:
-
- a.
- If a line was previously inserted as part of this command, it shall be set to the indentation of the last inserted line by default, or as otherwise specified for the eof character in Scroll.
- b.
- Otherwise, if the command is the ex a command, it shall be set to the line appended after, if any; otherwise to the first column.
- c.
- Otherwise, if the command is the ex i command, it shall be set to the line inserted before, if any; otherwise to the first column.
- d.
- Otherwise, if the command is the ex c command, it shall be set to the indentation of the line replaced.
-
autoprint, ap
[Default set] If autoprint is set, the current line shall be written after each ex command that modifies the contents of the current edit buffer, and after each tag command for which the tag search pattern was found or tag line number was valid, unless:- 1.
- The command was executed while in open or visual mode.
- 2.
- The command was executed as part of a global or v command or @ buffer execution.
- 3.
- The command was the form of the read command that reads a file into the edit buffer.
- 4.
- The command was the append, change, or insert command.
- 5.
- The command was not terminated by a <newline>.
- 6.
- The current line shall be written by a flag specified to the command; for example, delete # shall write the current line as specified for the flag modifier to the delete command, and not as specified by the autoprint edit option.
autowrite, aw
[Default unset] If autowrite is set, and the edit buffer has been modified since it was last completely written to any file, the contents of the edit buffer shall be written as if the ex write command had been specified without arguments, before each command affected by the autowrite edit option is executed. Appending the character '!' to the command name of any of the ex commands except '!' shall prevent the write. If the write fails, it shall be an error and the command shall not be executed.beautify, bf
[Default unset] If beautify is set, all non-printable characters, other than <tab>, <newline>, and <form-feed> characters, shall be discarded from text read in from files.directory, dir
[Default implementation-defined] The value of this option specifies the directory in which the editor buffer is to be placed. If this directory is not writable by the user, the editor shall quit.edcompatible, ed
[Default unset] Causes the presence of g and c suffixes on substitute commands to be remembered, and toggled by repeating the suffixes.errorbells, eb
[Default unset] If the editor is in ex mode, and the terminal does not support a standout mode (such as inverse video), and errorbells is set, error messages shall be preceded by alerting the terminal.exrc
[Default unset] If exrc is set, ex shall access any .exrc file in the current directory, as described in Initialization in ex and vi. If exrc is not set, ex shall ignore any .exrc file in the current directory during initialization, unless the current directory is that named by the HOME environment variable.ignorecase, ic
[Default unset] If ignorecase is set, characters that have uppercase and lowercase representations shall have those representations considered as equivalent for purposes of regular expression comparison. The ignorecase edit option shall affect all remembered regular expressions; for example, unsetting the ignorecase edit option shall cause a subsequent vi n command to search for the last basic regular expression in a case-sensitive fashion.list
[Default unset] If list is set, edit buffer lines written while in ex command mode shall be written as specified for the print command with the l flag specified. In open or visual mode, each edit buffer line shall be displayed as specified for the ex print command with the l flag specified. In open or visual text input mode, when the cursor does not rest on any character in the line, it shall rest on the '$' marking the end of the line.magic
[Default set] If magic is set, modify the interpretation of characters in regular expressions and substitution replacement strings (see Regular Expressions in ex and Replacement Strings in ex).mesg
[Default set] If mesg is set, the permission for others to use the write or talk commands to write to the terminal shall be turned on while in open or visual mode. The shell-level command mesg n shall take precedence over any setting of the ex mesg option; that is, if mesg y was issued before the editor started (or in a shell escape), such as:
-
:!mesg y
number, nu
[Default unset] If number is set, edit buffer lines written while in ex command mode shall be written with line numbers, in the format specified by the print command with the # flag specified. In ex text input mode, each line shall be preceded by the line number it will have in the file. In open or visual mode, each edit buffer line shall be displayed with a preceding line number, in the format specified by the ex print command with the # flag specified. This line number shall not be considered part of the line for the purposes of evaluating the current column; that is, column position 1 shall be the first column position after the format specified by the print command.paragraphs, para
[Default in the POSIX locale IPLPPPQPP LIpplpipbp] The paragraphs edit option shall define additional paragraph boundaries for the open and visual mode commands. The paragraphs edit option can be set to a character string consisting of zero or more character pairs. It shall be an error to set it to an odd number of characters.prompt
[Default set] If prompt is set, ex command mode input shall be prompted for with a <colon> (':'); when unset, no prompt shall be written.readonly
[Default see text] If the readonly edit option is set, read-only mode shall be enabled (see Write). The readonly edit option shall be initialized to set if either of the following conditions are true:- *
- The command-line option -R was specified.
- *
-
Performing actions equivalent to the
access()
function called with the following arguments indicates that the file
lacks write permission:
-
- 1.
- The current pathname is used as the path argument.
- 2.
- The constant W_OK is used as the amode argument.
-
redraw
[Default unset] The editor simulates an intelligent terminal on a dumb terminal. (Since this is likely to require a large amount of output to the terminal, it is useful only at high transmission speeds.)remap
[Default set] If remap is set, map translation shall allow for maps defined in terms of other maps; translation shall continue until a final product is obtained. If unset, only a one-step translation shall be done.report
[Default 5] The value of this report edit option specifies what number of lines being added, copied, deleted, or modified in the edit buffer will cause an informational message to be written to the user. The following conditions shall cause an informational message. The message shall contain the number of lines added, copied, deleted, or modified, but is otherwise unspecified.- *
- An ex or vi editor command, other than open, undo, or visual, that modifies at least the value of the report edit option number of lines, and which is not part of an ex global or v command, or ex or vi buffer execution, shall cause an informational message to be written.
- *
- An ex yank or vi y or Y command, that copies at least the value of the report edit option plus 1 number of lines, and which is not part of an ex global or v command, or ex or vi buffer execution, shall cause an informational message to be written.
- *
- An ex global, v, open, undo, or visual command or ex or vi buffer execution, that adds or deletes a total of at least the value of the report edit option number of lines, and which is not part of an ex global or v command, or ex or vi buffer execution, shall cause an informational message to be written. (For example, if 3 lines were added and 8 lines deleted during an ex visual command, 5 would be the number compared against the report edit option after the command completed.)
scroll, scr
[Default (number of lines in the display -1)/2] The value of the scroll edit option shall determine the number of lines scrolled by the ex <control>-D and z commands. For the vi <control>-D and <control>-U commands, it shall be the initial number of lines to scroll when no previous <control>-D or <control>-U command has been executed.sections
[Default in the POSIX locale NHSHH HUnhsh] The sections edit option shall define additional section boundaries for the open and visual mode commands. The sections edit option can be set to a character string consisting of zero or more character pairs; it shall be an error to set it to an odd number of characters.shell, sh
[Default from the environment variable SHELL] The value of this option shall be a string. The default shall be taken from the SHELL environment variable. If the SHELL environment variable is null or empty, the sh (see sh) utility shall be the default.shiftwidth, sw
[Default 8] The value of this option shall give the width in columns of an indentation level used during autoindentation and by the shift commands (< and >).showmatch, sm
[Default unset] The functionality described for the showmatch edit option need not be supported on block-mode terminals or terminals with insufficient capabilities. If showmatch is set, in open or visual mode, when a ')' or '}' is typed, if the matching '(' or '{' is currently visible on the display, the matching '(' or '{' shall be flagged moving the cursor to its location for an unspecified amount of time.showmode
[Default unset] If showmode is set, in open or visual mode, the current mode that the editor is in shall be displayed on the last line of the display. Command mode and text input mode shall be differentiated; other unspecified modes and implementation-defined information may be displayed.slowopen
[Default unset] If slowopen is set during open and visual text input modes, the editor shall not update portions of the display other than those display line columns that display the characters entered by the user (see Input Mode Commands in vi).tabstop, ts
[Default 8] The value of this edit option shall specify the column boundary used by a <tab> in the display (see autoprint, ap and Input Mode Commands in vi).taglength, tl
[Default zero] The value of this edit option shall specify the maximum number of characters that are considered significant in the user-specified tag name and in the tag name from the tags file. If the value is zero, all characters in both tag names shall be significant.tags
[Default see text] The value of this edit option shall be a string of <blank>-delimited pathnames of files used by the tag command. The default value is unspecified.term
[Default from the environment variable TERM] The value of this edit option shall be a string. The default shall be taken from the TERM variable in the environment. If the TERM environment variable is empty or null, the default is unspecified. The editor shall use the value of this edit option to determine the type of the display device. The results are unspecified if the user changes the value of the term edit option after editor initialization.terse
[Default unset] If terse is set, error messages may be less verbose. However, except for this caveat, error messages are unspecified. Furthermore, not all error messages need change for different settings of this option.warn
[Default set] If warn is set, and the contents of the edit buffer have been modified since they were last completely written, the editor shall write a warning message before certain ! commands (see Escape).window
[Default see text] A value used in open and visual mode, by the <control>-B and <control>-F commands, and, in visual mode, to specify the number of lines displayed when the screen is repainted. If the -w command-line option is not specified, the default value shall be set to the value of the LINES environment variable. If the LINES environment variable is empty or null, the default shall be the number of lines in the display minus 1. Setting the window edit option to zero or to a value greater than the number of lines in the display minus 1 (either explicitly or based on the -w option or the LINES environment variable) shall cause the window edit option to be set to the number of lines in the display minus 1. The baud rate of the terminal line may change the default in an implementation-defined manner.wrapmargin, wm
[Default 0] If the value of this edit option is zero, it shall have no effect. If not in the POSIX locale, the effect of this edit option is implementation-defined. Otherwise, it shall specify a number of columns from the ending margin of the terminal. During open and visual text input modes, for each character for which any part of the character is displayed in a column that is less than wrapmargin columns from the ending margin of the display line, the editor shall behave as follows:- 1.
- If the character triggering this event is a <blank>, it, and all immediately preceding <blank> characters on the current line entered during the execution of the current text input command, shall be discarded, and the editor shall behave as if the user had entered a single <newline> instead. In addition, if the next user-entered character is a <space>, it shall be discarded as well.
- 2.
- Otherwise, if there are one or more <blank> characters on the current line immediately preceding the last group of inserted non-<blank> characters which was entered during the execution of the current text input command, the <blank> characters shall be replaced as if the user had entered a single <newline> instead. If the autoindent edit option is set, and the events described in 1. or 2. are performed, any <blank> characters at or after the cursor in the current line shall be discarded. The ending margin shall be determined by the system or overridden by the user, as described for COLUMNS in the ENVIRONMENT VARIABLES section and the Base Definitions volume of POSIX.1-2008, Chapter 8, Environment Variables.
wrapscan, ws
[Default set] If wrapscan is set, searches (the ex / or ? addresses, or open and visual mode /, ?, N, and n commands) shall wrap around the beginning or end of the edit buffer; when unset, searches shall stop at the beginning or end of the edit buffer.writeany, wa
[Default unset] If writeany is set, some of the checks performed when executing the ex write commands shall be inhibited, as described in editor option autowrite.EXIT STATUS
The following exit values shall be returned:- 0
- Successful completion.
- >0
- An error occurred.
CONSEQUENCES OF ERRORS
When any error is encountered and the standard input is not a terminal device file, ex shall not write the file or return to command or text input mode, and shall terminate with a non-zero exit status. Otherwise, when an unrecoverable error is encountered, it shall be equivalent to a SIGHUP asynchronous event. Otherwise, when an error is encountered, the editor shall behave as specified in Command Line Parsing in ex.The following sections are informative.
APPLICATION USAGE
If a SIGSEGV signal is received while ex is saving a file, the file might not be successfully saved. The next command can accept more than one file, so usage such as:
-
next `ls [abc]*`
EXAMPLES
None.RATIONALE
The ex/vi specification is based on the historical practice found in the 4 BSD and System V implementations of ex and vi. A restricted editor (both the historical red utility and modifications to ex) were considered and rejected for inclusion. Neither option provided the level of security that users might expect. It is recognized that ex visual mode and related features would be difficult, if not impossible, to implement satisfactorily on a block-mode terminal, or a terminal without any form of cursor addressing; thus, it is not a mandatory requirement that such features should work on all terminals. It is the intention, however, that an ex implementation should provide the full set of capabilities on all terminals capable of supporting them.Options
The -c replacement for +command was inspired by the -e option of sed. Historically, all such commands (see edit and next as well) were executed from the last line of the edit buffer. This meant, for example, that dq+/patterndq would fail unless the wrapscan option was set. POSIX.1-2008 requires conformance to historical practice. The +command option is no longer specified by POSIX.1-2008 but may be present in some implementations. Historically, some implementations restricted the ex commands that could be listed as part of the command line arguments. For consistency, POSIX.1-2008 does not permit these restrictions. In historical implementations of the editor, the -R option (and the readonly edit option) only prevented overwriting of files; appending to files was still permitted, mapping loosely into the csh noclobber variable. Some implementations, however, have not followed this semantic, and readonly does not permit appending either. POSIX.1-2008 follows the latter practice, believing that it is a more obvious and intuitive meaning of readonly. The -s option suppresses all interactive user feedback and is useful for editing scripts in batch jobs. The list of specific effects is historical practice. The terminal type ``incapable of supporting open and visual modes'' has historically been named ``dumb''. The -t option was required because the ctags utility appears in POSIX.1-2008 and the option is available in all historical implementations of ex. Historically, the ex and vi utilities accepted a -x option, which did encryption based on the algorithm found in the historical crypt utility. The -x option for encryption, and the associated crypt utility, were omitted because the algorithm used was not specifiable and the export control laws of some nations make it difficult to export cryptographic technology. In addition, it did not historically provide the level of security that users might expect.Standard Input
An end-of-file condition is not equivalent to an end-of-file character. A common end-of-file character, <control>-D, is historically an ex command. There was no maximum line length in historical implementations of ex. Specifically, as it was parsed in chunks, the addresses had a different maximum length than the filenames. Further, the maximum line buffer size was declared as BUFSIZ, which was different lengths on different systems. This version selected the value of {LINE_MAX} to impose a reasonable restriction on portable usage of ex and to aid test suite writers in their development of realistic tests that exercise this limit.Input Files
It was an explicit decision by the standard developers that a <newline> be added to any file lacking one. It was believed that this feature of ex and vi was relied on by users in order to make text files lacking a trailing <newline> more portable. It is recognized that this will require a user-specified option or extension for implementations that permit ex and vi to edit files of type other than text if such files are not otherwise identified by the system. It was agreed that the ability to edit files of arbitrary type can be useful, but it was not considered necessary to mandate that an ex or vi implementation be required to handle files other than text files. The paragraph in the INPUT FILES section, ``By default, ...'', is intended to close a long-standing security problem in ex and vi; that of the ``modeline'' or ``modelines'' edit option. This feature allows any line in the first or last five lines of the file containing the strings dqex:dq or dqvi:dq (and, apparently, dqei:dq or dqvx:dq) to be a line containing editor commands, and ex interprets all the text up to the next ':' or <newline> as a command. Consider the consequences, for example, of an unsuspecting user using ex or vi as the editor when replying to a mail message in which a line such as:
-
ex:! rm -rf :
Asynchronous Events
The intention of the phrase ``complete write'' is that the entire edit buffer be written to stable storage. The note regarding temporary files is intended for implementations that use temporary files to back edit buffers unnamed by the user. Historically, SIGQUIT was ignored by ex, but was the equivalent of the Q command in visual mode; that is, it exited visual mode and entered ex mode. POSIX.1-2008 permits, but does not require, this behavior. Historically, SIGINT was often used by vi users to terminate text input mode (<control>-C is often easier to enter than <ESC>). Some implementations of vi alerted the terminal on this event, and some did not. POSIX.1-2008 requires that SIGINT behave identically to <ESC>, and that the terminal not be alerted. Historically, suspending the ex editor during text input mode was similar to SIGINT, as completed lines were retained, but any partial line discarded, and the editor returned to command mode. POSIX.1-2008 is silent on this issue; implementations are encouraged to follow historical practice, where possible. Historically, the vi editor did not treat SIGTSTP as an asynchronous event, and it was therefore impossible to suspend the editor in visual text input mode. There are two major reasons for this. The first is that SIGTSTP is a broadcast signal on UNIX systems, and the chain of events where the shell execs an application that then execs vi usually caused confusion for the terminal state if SIGTSTP was delivered to the process group in the default manner. The second was that most implementations of the UNIX curses package did not handle SIGTSTP safely, and the receipt of SIGTSTP at the wrong time would cause them to crash. POSIX.1-2008 is silent on this issue; implementations are encouraged to treat suspension as an asynchronous event if possible. Historically, modifications to the edit buffer made before SIGINT interrupted an operation were retained; that is, anywhere from zero to all of the lines to be modified might have been modified by the time the SIGINT arrived. These changes were not discarded by the arrival of SIGINT. POSIX.1-2008 permits this behavior, noting that the undo command is required to be able to undo these partially completed commands. The action taken for signals other than SIGINT, SIGCONT, SIGHUP, and SIGTERM is unspecified because some implementations attempt to save the edit buffer in a useful state when other signals are received.Standard Error
For ex/vi, diagnostic messages are those messages reported as a result of a failed attempt to invoke ex or vi, such as invalid options or insufficient resources, or an abnormal termination condition. Diagnostic messages should not be confused with the error messages generated by inappropriate or illegal user commands.Initialization in ex and vi
If an ex command (other than cd, chdir, or source) has a filename argument, one or both of the alternate and current pathnames will be set. Informally, they are set as follows:- 1.
- If the ex command is one that replaces the contents of the edit buffer, and it succeeds, the current pathname will be set to the filename argument (the first filename argument in the case of the next command) and the alternate pathname will be set to the previous current pathname, if there was one.
- 2.
- In the case of the file read/write forms of the read and write commands, if there is no current pathname, the current pathname will be set to the filename argument.
- 3.
-
Otherwise, the alternate pathname will be set to the filename
argument.
For example,
:edit foo
and
:recover foo,
when successful, set the current pathname, and, if there was a
previous current pathname, the alternate pathname. The commands
:write,
!command,
and
:edit
set neither the current or alternate pathnames. If the
:edit foo
command were to fail for some reason, the alternate pathname would be
set. The
read
and
write
commands set the alternate pathname to their
file
argument, unless the current pathname is not set, in which case they
set the current pathname to their
file
arguments. The alternate pathname was not historically set by the
:source
command. POSIX.1-2008 requires conformance to historical practice.
Implementations adding commands that take filenames as arguments are
encouraged to set the alternate pathname as described here.
Historically,
ex
and
vi
read the
.exrc
file in the
$HOME
directory twice, if the editor was executed in the
$HOME
directory. POSIX.1-2008 prohibits this behavior.
Historically, the 4 BSD
ex
and
vi
read the
$HOME
and local
.exrc
files if they were owned by the real ID of the user, or the
sourceany
option was set, regardless of other considerations. This was a security
problem because it is possible to put normal UNIX system commands
inside a
.exrc
file. POSIX.1-2008 does not specify the
sourceany
option, and historical implementations are encouraged to delete it.
The
.exrc
files must be owned by the real ID of the user, and not writable by
anyone other than the owner. The appropriate privileges exception is
intended to permit users to acquire special privileges, but continue to
use the
.exrc
files in their home directories.
System V Release 3.2 and later
vi
implementations added the option
[no]exrc.
The behavior is that local
.exrc
files are read-only if the
exrc
option is set. The default for the
exrc
option was off, so by default, local
.exrc
files were not read. The problem this was intended to solve was that
System V permitted users to give away files, so there is no possible
ownership or writeability test to ensure that the file is safe. This is
still a security problem on systems where users can give away files,
but there is nothing additional that POSIX.1-2008 can do. The
implementation-defined exception is intended to permit groups to have
local
.exrc
files that are shared by users, by creating pseudo-users to own the
shared files.
POSIX.1-2008 does not mention system-wide
ex
and
vi
start-up files. While they exist in several implementations of
ex
and
vi,
they are not present in any implementations considered historical
practice by POSIX.1-2008. Implementations that have such files should use them
only if they are owned by the real user ID or an appropriate user (for
example, root on UNIX systems) and if they are not writable by any
user other than their owner. System-wide start-up files should be read
before the
EXINIT
variable,
$HOME/.exrc,
or local
.exrc
files are evaluated.
Historically, any
ex
command could be entered in the
EXINIT
variable or the
.exrc
file, although ones requiring that the edit buffer already contain
lines of text generally caused historical implementations of the editor
to drop
core.
POSIX.1-2008 requires that any
ex
command be permitted in the
EXINIT
variable and
.exrc
files, for simplicity of specification and consistency, although many
of them will obviously fail under many circumstances.
The initialization of the contents of the edit buffer uses the phrase
``the effect shall be'' with regard to various
ex
commands. The intent of this phrase is that edit buffer contents loaded
during the initialization phase not be lost; that is, loading the edit
buffer should fail if the
.exrc
file read in the contents of a file and did not subsequently write the
edit buffer. An additional intent of this phrase is to specify that the
initial current line and column is set as specified for the individual
ex
commands.
Historically, the
-t
option behaved as if the tag search were a
+command;
that is, it was executed from the last line of the file specified by
the tag. This resulted in the search failing if the pattern was a
forward search pattern and the
wrapscan
edit option was not set. POSIX.1-2008 does not permit this behavior, requiring
that the search for the tag pattern be performed on the entire file,
and, if not found, that the current line be set to a more reasonable
location in the file.
Historically, the empty edit buffer presented for editing when a file
was not specified by the user was unnamed. This is permitted by POSIX.1-2008;
however, implementations are encouraged to provide users a temporary
filename for this buffer because it permits them the use of
ex
commands that use the current pathname during temporary edit
sessions.
Historically, the file specified using the
-t
option was not part of the current argument list. This practice is
permitted by POSIX.1-2008; however, implementations are encouraged to include
its name in the current argument list for consistency.
Historically, the
-c
command was generally not executed until a file that already exists was
edited. POSIX.1-2008 requires conformance to this historical practice.
Commands that could cause the
-c
command to be executed include the
ex
commands
edit,
next,
recover,
rewind,
and
tag,
and the
vi
commands
<control>-^
and
<control>-].
Historically, reading a file into an edit buffer did not cause the
-c
command to be executed (even though it might set the current pathname)
with the exception that it did cause the
-c
command to be executed if: the editor was in
ex
mode, the edit buffer had no current pathname, the edit buffer was
empty, and no read commands had yet been attempted. For consistency and
simplicity of specification, POSIX.1-2008 does not permit this behavior.
Historically, the
-r
option was the same as a normal edit session if there was no recovery
information available for the file. This allowed users to enter:
-
vi -r *.c
-
Addressing
Historically, ex and vi accepted the additional addressing forms '\/' and '\?'. They were equivalent to dq//dq and dq??dq, respectively. They are not required by POSIX.1-2008, mostly because nobody can remember whether they ever did anything different historically. Historically, ex and vi permitted an address of zero for several commands, and permitted the % address in empty files for others. For consistency, POSIX.1-2008 requires support for the former in the few commands where it makes sense, and disallows it otherwise. In addition, because POSIX.1-2008 requires that % be logically equivalent to dq1,$dq, it is also supported where it makes sense and disallowed otherwise. Historically, the % address could not be followed by further addresses. For consistency and simplicity of specification, POSIX.1-2008 requires that additional addresses be supported. All of the following are valid addresses:- +++
- Three lines after the current line.
- /re/-
- One line before the next occurrence of re.
- -2
- Two lines before the current line.
- 3 ---- 2
- Line one (note intermediate negative address).
- 1 2 3
- Line six. Any number of addresses can be provided to commands taking addresses; for example, dq1,2,3,4,5pdq prints lines 4 and 5, because two is the greatest valid number of addresses accepted by the print command. This, in combination with the <semicolon> delimiter, permits users to create commands based on ordered patterns in the file. For example, the command 3;/foo/;+2print will display the first line after line 3 that contains the pattern foo, plus the next two lines. Note that the address 3; must be evaluated before being discarded because the search origin for the /foo/ command depends on this. Historically, values could be added to addresses by including them after one or more <blank> characters; for example, 3 - 5p wrote the seventh line of the file, and /foo/ 5 was the same as /foo/+5. However, only absolute values could be added; for example, 5 /foo/ was an error. POSIX.1-2008 requires conformance to historical practice. Address offsets are separately specified from addresses because they could historically be provided to visual mode search commands. Historically, any missing addresses defaulted to the current line. This was true for leading and trailing <comma>-delimited addresses, and for trailing <semicolon>-delimited addresses. For consistency, POSIX.1-2008 requires it for leading <semicolon> addresses as well. Historically, ex and vi accepted the '^' character as both an address and as a flag offset for commands. In both cases it was identical to the '-' character. POSIX.1-2008 does not require or prohibit this behavior. Historically, the enhancements to basic regular expressions could be used in addressing; for example, '~', '\<', and '\>'. POSIX.1-2008 requires conformance to historical practice; that is, that regular expression usage be consistent, and that regular expression enhancements be supported wherever regular expressions are used.
Command Line Parsing in ex
Historical ex command parsing was even more complex than that described here. POSIX.1-2008 requires the subset of the command parsing that the standard developers believed was documented and that users could reasonably be expected to use in a portable fashion, and that was historically consistent between implementations. (The discarded functionality is obscure, at best.) Historical implementations will require changes in order to comply with POSIX.1-2008; however, users are not expected to notice any of these changes. Most of the complexity in ex parsing is to handle three special termination cases:- 1.
- The !, global, v, and the filter versions of the read and write commands are delimited by <newline> characters (they can contain <vertical-line> characters that are usually shell pipes).
- 2.
- The ex, edit, next, and visual in open and visual mode commands all take ex commands, optionally containing <vertical-line> characters, as their first arguments.
- 3.
-
The
s
command takes a regular expression as its first argument, and uses the
delimiting characters to delimit the command.
Historically,
<vertical-line>
characters in the
+command
argument of the
ex,
edit,
next,
vi,
and
visual
commands, and in the
pattern
and
replacement
parts of the
s
command, did not delimit the command, and in the filter cases for
read
and
write,
and the
!,
global,
and
v
commands, they did not delimit the command at all. For example, the
following commands are all valid:
-
:edit +25 | s/abc/ABC/ file.c :s/ | /PIPE/ :read !spell % | columnate :global/pattern/p | l :s/a/b/ | s/c/d | set
-
:edit +25 file.c | s/abc/ABC/ | 1
-
echo 'foo | bar' > file1; echo 'foo/bar' > file2; vi :edit +1 | s/|/PIPE/ | w file1 | e file2 | 1 | s/\//SLASH/ | wq
-
map = foo<control-V><newline>bar
-
Input Editing in ex
One of the common uses of the historical ex editor is over slow network connections. Editors that run in canonical mode can require far less traffic to and from, and far less processing on, the host machine, as well as more easily supporting block-mode terminals. For these reasons, POSIX.1-2008 requires that ex be implemented using canonical mode input processing, as was done historically. POSIX.1-2008 does not require the historical 4 BSD input editing characters ``word erase'' or ``literal next''. For this reason, it is unspecified how they are handled by ex, although they must have the required effect. Implementations that resolve them after the line has been ended using a <newline> or <control>-M character, and implementations that rely on the underlying system terminal support for this processing, are both conforming. Implementations are strongly urged to use the underlying system functionality, if at all possible, for compatibility with other system text input interfaces. Historically, when the eof character was used to decrement the autoindent level, the cursor moved to display the new end of the autoindent characters, but did not move the cursor to a new line, nor did it erase the <control>-D character from the line. POSIX.1-2008 does not specify that the cursor remain on the same line or that the rest of the line is erased; however, implementations are strongly encouraged to provide the best possible user interface; that is, the cursor should remain on the same line, and any <control>-D character on the line should be erased. POSIX.1-2008 does not require the historical 4 BSD input editing character ``reprint'', traditionally <control>-R, which redisplayed the current input from the user. For this reason, and because the functionality cannot be implemented after the line has been terminated by the user, POSIX.1-2008 makes no requirements about this functionality. Implementations are strongly urged to make this historical functionality available, if possible. Historically, <control>-Q did not perform a literal next function in ex, as it did in vi. POSIX.1-2008 requires conformance to historical practice to avoid breaking historical ex scripts and .exrc files.eof
Whether the eof character immediately modifies the autoindent characters in the prompt is left unspecified so that implementations can conform in the presence of systems that do not support this functionality. Implementations are encouraged to modify the line and redisplay it immediately, if possible. The specification of the handling of the eof character differs from historical practice only in that eof characters are not discarded if they follow normal characters in the text input. Historically, they were always discarded.Command Descriptions in ex
Historically, several commands (for example, global, v, visual, s, write, wq, yank, !, <, >, &, and ~) were executable in empty files (that is, the default address(es) were 0), or permitted explicit addresses of 0 (for example, 0 was a valid address, or 0,0 was a valid range). Addresses of 0, or command execution in an empty file, make sense only for commands that add new text to the edit buffer or write commands (because users may wish to write empty files). POSIX.1-2008 requires this behavior for such commands and disallows it otherwise, for consistency and simplicity of specification. A count to an ex command has been historically corrected to be no greater than the last line in a file; for example, in a five-line file, the command 1,6print would fail, but the command 1print300 would succeed. POSIX.1-2008 requires conformance to historical practice. Historically, the use of flags in ex commands could be obscure. General historical practice was as described by POSIX.1-2008, but there were some special cases. For instance, the list, number, and print commands ignored trailing address offsets; for example, 3p +++# would display line 3, and 3 would be the current line after the execution of the command. The open and visual commands ignored both the trailing offsets and the trailing flags. Also, flags specified to the open and visual commands interacted badly with the list edit option, and setting and then unsetting it during the open/visual session would cause vi to stop displaying lines in the specified format. For consistency and simplicity of specification, POSIX.1-2008 does not permit any of these exceptions to the general rule. POSIX.1-2008 uses the word copy in several places when discussing buffers. This is not intended to imply implementation. Historically, ex users could not specify numeric buffers because of the ambiguity this would cause; for example, in the command 3 delete 2, it is unclear whether 2 is a buffer name or a count. POSIX.1-2008 requires conformance to historical practice by default, but does not preclude extensions. Historically, the contents of the unnamed buffer were frequently discarded after commands that did not explicitly affect it; for example, when using the edit command to switch files. For consistency and simplicity of specification, POSIX.1-2008 does not permit this behavior. The ex utility did not historically have access to the numeric buffers, and, furthermore, deleting lines in ex did not modify their contents. For example, if, after doing a delete in vi, the user switched to ex, did another delete, and then switched back to vi, the contents of the numeric buffers would not have changed. POSIX.1-2008 requires conformance to historical practice. Numeric buffers are described in the ex utility in order to confine the description of buffers to a single location in POSIX.1-2008. The metacharacters that trigger shell expansion in file arguments match historical practice, as does the method for doing shell expansion. Implementations wishing to provide users with the flexibility to alter the set of metacharacters are encouraged to provide a shellmeta string edit option. Historically, ex commands executed from vi refreshed the screen when it did not strictly need to do so; for example, :!date > /dev/null does not require a screen refresh because the output of the UNIX date command requires only a single line of the screen. POSIX.1-2008 requires that the screen be refreshed if it has been overwritten, but makes no requirements as to how an implementation should make that determination. Implementations may prompt and refresh the screen regardless.Abbreviate
Historical practice was that characters that were entered as part of an abbreviation replacement were subject to map expansions, the showmatch edit option, further abbreviation expansions, and so on; that is, they were logically pushed onto the terminal input queue, and were not a simple replacement. POSIX.1-2008 requires conformance to historical practice. Historical practice was that whenever a non-word character (that had not been escaped by a <control>-V) was entered after a word character, vi would check for abbreviations. The check was based on the type of the character entered before the word character of the word/non-word pair that triggered the check. The word character of the word/non-word pair that triggered the check and all characters entered before the trigger pair that were of that type were included in the check, with the exception of <blank> characters, which always delimited the abbreviation. This means that, for the abbreviation to work, the lhs must end with a word character, there can be no transitions from word to non-word characters (or vice versa) other than between the last and next-to-last characters in the lhs, and there can be no <blank> characters in the lhs. In addition, because of the historical quoting rules, it was impossible to enter a literal <control>-V in the lhs. POSIX.1-2008 requires conformance to historical practice. Historical implementations did not inform users when abbreviations that could never be used were entered; implementations are strongly encouraged to do so.For example, the following abbreviations will work:
-
:ab (p REPLACE :ab p REPLACE :ab ((p REPLACE
-
:ab ( REPLACE :ab (pp REPLACE
-
:ab foo bar :ab foo baz
-
:ab foo1 bar :ab foo2 bar :unabbreviate foo2
Append
Historically, any text following a <vertical-line> command separator after an append, change, or insert command became part of the insert text. For example, in the command:
-
:g/pattern/append|stuff1
-
:append|stuff1 stuff2 .
Change
See the RATIONALE for the append command. Historical practice for cursor positioning after the change command when no text is input, is as described in POSIX.1-2008. However, one System V implementation is known to have been modified such that the cursor is positioned on the first address specified, and not on the line before the first address. POSIX.1-2008 disallows this modification for consistency. Historically, the change command did not support buffer arguments, although some implementations allow the specification of an optional buffer. This behavior is neither required nor disallowed by POSIX.1-2008.Change Directory
A common extension in ex implementations is to use the elements of a cdpath edit option as prefix directories for path arguments to chdir that are relative pathnames and that do not have '.' or dq..dq as their first component. Elements in the cdpath edit option are <colon>-separated. The initial value of the cdpath edit option is the value of the shell CDPATH environment variable. This feature was not included in POSIX.1-2008 because it does not exist in any of the implementations considered historical practice.Copy
Historical implementations of ex permitted copies to lines inside of the specified range; for example, :2,5copy3 was a valid command. POSIX.1-2008 requires conformance to historical practice.Delete
POSIX.1-2008 requires support for the historical parsing of a delete command followed by flags, without any intervening <blank> characters. For example:- 1dp
- Deletes the first line and prints the line that was second.
- 1delep
- As for 1dp.
- 1d
- Deletes the first line, saving it in buffer p.
- 1d p1l
- (Pee-one-ell.) Deletes the first line, saving it in buffer p, and listing the line that was second.
Edit
Historically, any ex command could be entered as a +command argument to the edit command, although some (for example, insert and append) were known to confuse historical implementations. For consistency and simplicity of specification, POSIX.1-2008 requires that any command be supported as an argument to the edit command. Historically, the command argument was executed with the current line set to the last line of the file, regardless of whether the edit command was executed from visual mode or not. POSIX.1-2008 requires conformance to historical practice. Historically, the +command specified to the edit and next commands was delimited by the first <blank>, and there was no way to quote them. For consistency, POSIX.1-2008 requires that the usual ex backslash quoting be provided. Historically, specifying the +command argument to the edit command required a filename to be specified as well; for example, :edit +100 would always fail. For consistency and simplicity of specification, POSIX.1-2008 does not permit this usage to fail for that reason. Historically, only the cursor position of the last file edited was remembered by the editor. POSIX.1-2008 requires that this be supported; however, implementations are permitted to remember and restore the cursor position for any file previously edited.File
Historical versions of the ex editor file command displayed a current line and number of lines in the edit buffer of 0 when the file was empty, while the vi <control>-G command displayed a current line and number of lines in the edit buffer of 1 in the same situation. POSIX.1-2008 does not permit this discrepancy, instead requiring that a message be displayed indicating that the file is empty.Global
The two-pass operation of the global and v commands is not intended to imply implementation, only the required result of the operation. The current line and column are set as specified for the individual ex commands. This requirement is cumulative; that is, the current line and column must track across all the commands executed by the global or v commands.Insert
See the RATIONALE for the append command. Historically, insert could not be used with an address of zero; that is, not when the edit buffer was empty. POSIX.1-2008 requires that this command behave consistently with the append command.Join
The action of the join command in relation to the special characters is only defined for the POSIX locale because the correct amount of white space after a period varies; in Japanese none is required, in French only a single space, and so on.List
The historical output of the list command was potentially ambiguous. The standard developers believed correcting this to be more important than adhering to historical practice, and POSIX.1-2008 requires unambiguous output.Map
Historically, command mode maps only applied to command names; for example, if the character 'x' was mapped to 'y', the command fx searched for the 'x' character, not the 'y' character. POSIX.1-2008 requires this behavior. Historically, entering <control>-V as the first character of a vi command was an error. Several implementations have extended the semantics of vi such that <control>-V means that the subsequent command character is not mapped. This is permitted, but not required, by POSIX.1-2008. Regardless, using <control>-V to escape the second or later character in a sequence of characters that might match a map command, or any character in text input mode, is historical practice, and stops the entered keys from matching a map. POSIX.1-2008 requires conformance to historical practice. Historical implementations permitted digits to be used as a map command lhs, but then ignored the map. POSIX.1-2008 requires that the mapped digits not be ignored. The historical implementation of the map command did not permit map commands that were more than a single character in length if the first character was printable. This behavior is permitted, but not required, by POSIX.1-2008. Historically, mapped characters were remapped unless the remap edit option was not set, or the prefix of the mapped characters matched the mapping characters; for example, in the map:
-
:map ab abcd
-
:map! ab short :map! abc long
-
:map! abc long :map! ab short
Mark
Historically, users were able to set the ``previous context'' marks explicitly. In addition, the ex commands '' and '` and the vi commands '', ``, `', and '` all referred to the same mark. In addition, the previous context marks were not set if the command, with which the address setting the mark was associated, failed. POSIX.1-2008 requires conformance to historical practice. Historically, if marked lines were deleted, the mark was also deleted, but would reappear if the change was undone. POSIX.1-2008 requires conformance to historical practice. The description of the special events that set the ` and ' marks matches historical practice. For example, historically the command /a/,/b/ did not set the ` and ' marks, but the command /a/,/b/delete did.Next
Historically, any ex command could be entered as a +command argument to the next command, although some (for example, insert and append) were known to confuse historical implementations. POSIX.1-2008 requires that any command be permitted and that it behave as specified. The next command can accept more than one file, so usage such as:
-
next `ls [abc] `
Open
Historically, the open command would fail if the open edit option was not set. POSIX.1-2008 does not mention the open edit option and does not require this behavior. Some historical implementations do not permit entering open mode from open or visual mode, only from ex mode. For consistency, POSIX.1-2008 does not permit this behavior. Historically, entering open mode from the command line (that is, vi +open) resulted in anomalous behaviors; for example, the ex file and set commands, and the vi command <control>-G did not work. For consistency, POSIX.1-2008 does not permit this behavior. Historically, the open command only permitted '/' characters to be used as the search pattern delimiter. For consistency, POSIX.1-2008 requires that the search delimiters used by the s, global, and v commands be accepted as well.Preserve
The preserve command does not historically cause the file to be considered unmodified for the purposes of future commands that may exit the editor. POSIX.1-2008 requires conformance to historical practice. Historical documentation stated that mail was not sent to the user when preserve was executed; however, historical implementations did send mail in this case. POSIX.1-2008 requires conformance to the historical implementations.- 1.
- Printable characters are left alone.
- 2.
- Control characters less than \177 are represented as '^' followed by the character offset from the '@' character in the ASCII map; for example, \007 is represented as '^G'.
- 3.
- \177 is represented as '^' followed by '?'. The display of characters having their eighth bit set was less standard. Existing implementations use hex (0x00), octal (\000), and a meta-bit display. (The latter displayed bytes that had their eighth bit set as the two characters dqM-dq followed by the seven-bit display as described above.) The latter probably has the best claim to historical practice because it was used for the -v option of 4 BSD and 4 BSD-derived versions of the cat utility since 1980. No specific display format is required by POSIX.1-2008. Explicit dependence on the ASCII character set has been avoided where possible, hence the use of the phrase an ``implementation-defined multi-character sequence'' for the display of non-printable characters in preference to the historical usage of, for instance, dq^Idq for the <tab>. Implementations are encouraged to conform to historical practice in the absence of any strong reason to diverge. Historically, all ex commands beginning with the letter 'p' could be entered using capitalized versions of the commands; for example, P[rint], Pre[serve], and Pu[t] were all valid command names. POSIX.1-2008 permits, but does not require, this historical practice because capital forms of the commands are used by some implementations for other purposes.
Put
Historically, an ex put command, executed from open or visual mode, was the same as the open or visual mode P command, if the buffer was named and was cut in character mode, and the same as the p command if the buffer was named and cut in line mode. If the unnamed buffer was the source of the text, the entire line from which the text was taken was usually put, and the buffer was handled as if in line mode, but it was possible to get extremely anomalous behavior. In addition, using the Q command to switch into ex mode, and then doing a put often resulted in errors as well, such as appending text that was unrelated to the (supposed) contents of the buffer. For consistency and simplicity of specification, POSIX.1-2008 does not permit these behaviors. All ex put commands are required to operate in line mode, and the contents of the buffers are not altered by changing the mode of the editor.Read
Historically, an ex read command executed from open or visual mode, executed in an empty file, left an empty line as the first line of the file. For consistency and simplicity of specification, POSIX.1-2008 does not permit this behavior. Historically, a read in open or visual mode from a program left the cursor at the last line read in, not the first. For consistency, POSIX.1-2008 does not permit this behavior. Historical implementations of ex were unable to undo read commands that read from the output of a program. For consistency, POSIX.1-2008 does not permit this behavior. Historically, the ex and vi message after a successful read or write command specified ``characters'', not ``bytes''. POSIX.1-2008 requires that the number of bytes be displayed, not the number of characters, because it may be difficult in multi-byte implementations to determine the number of characters read. Implementations are encouraged to clarify the message displayed to the user. Historically, reads were not permitted on files other than type regular, except that FIFO files could be read (probably only because they did not exist when ex and vi were originally written). Because the historical ex evaluated read! and read ! equivalently, there can be no optional way to force the read. POSIX.1-2008 permits, but does not require, this behavior.Recover
Some historical implementations of the editor permitted users to recover the edit buffer contents from a previous edit session, and then exit without saving those contents (or explicitly discarding them). The intent of POSIX.1-2008 in requiring that the edit buffer be treated as already modified is to prevent this user error.Rewind
Historical implementations supported the rewind command when the user was editing the first file in the list; that is, the file that the rewind command would edit. POSIX.1-2008 requires conformance to historical practice.Substitute
Historically, ex accepted an r option to the s command. The effect of the r option was to use the last regular expression used in any command as the pattern, the same as the ~ command. The r option is not required by POSIX.1-2008. Historically, the c and g options were toggled; for example, the command :s/abc/def/ was the same as s/abc/def/ccccgggg. For simplicity of specification, POSIX.1-2008 does not permit this behavior. The tilde command is often used to replace the last search RE. For example, in the sequence:
-
s/red/blue/ /green ~
-
s/green/blue/
-
s/abc/def/ s/abc/def s/abc/ s/abc
Set
Historical implementations redisplayed all of the options for each occurrence of the all keyword. POSIX.1-2008 permits, but does not require, this behavior.Tag
No requirement is made as to where ex and vi shall look for the file referenced by the tag entry. Historical practice has been to look for the path found in the tags file, based on the current directory. A useful extension found in some implementations is to look based on the directory containing the tags file that held the entry, as well. No requirement is made as to which reference for the tag in the tags file is used. This is deliberate, in order to permit extensions such as multiple entries in a tags file for a tag. Because users often specify many different tags files, some of which need not be relevant or exist at any particular time, POSIX.1-2008 requires that error messages about problem tags files be displayed only if the requested tag is not found, and then, only once for each time that the tag edit option is changed. The requirement that the current edit buffer be unmodified is only necessary if the file indicated by the tag entry is not the same as the current file (as defined by the current pathname). Historically, the file would be reloaded if the filename had changed, as well as if the filename was different from the current pathname. For consistency and simplicity of specification, POSIX.1-2008 does not permit this behavior, requiring that the name be the only factor in the decision. Historically, vi only searched for tags in the current file from the current cursor to the end of the file, and therefore, if the wrapscan option was not set, tags occurring before the current cursor were not found. POSIX.1-2008 considers this a bug, and implementations are required to search for the first occurrence in the file, regardless.Undo
The undo description deliberately uses the word ``modified''. The undo command is not intended to undo commands that replace the contents of the edit buffer, such as edit, next, tag, or recover. Cursor positioning after the undo command was inconsistent in the historical vi, sometimes attempting to restore the original cursor position (global, undo, and v commands), and sometimes, in the presence of maps, placing the cursor on the last line added or changed instead of the first. POSIX.1-2008 requires a simplified behavior for consistency and simplicity of specification.Version
The version command cannot be exactly specified since there is no widely-accepted definition of what the version information should contain. Implementations are encouraged to do something reasonably intelligent.Write
Historically, the ex and vi message after a successful read or write command specified ``characters'', not ``bytes''. POSIX.1-2008 requires that the number of bytes be displayed, not the number of characters because it may be difficult in multi-byte implementations to determine the number of characters written. Implementations are encouraged to clarify the message displayed to the user. Implementation-defined tests are permitted so that implementations can make additional checks; for example, for locks or file modification times. Historically, attempting to append to a nonexistent file caused an error. It has been left unspecified in POSIX.1-2008 to permit implementations to let the write succeed, so that the append semantics are similar to those of the historical csh. Historical vi permitted empty edit buffers to be written. However, since the way vi got around dealing with ``empty'' files was to always have a line in the edit buffer, no matter what, it wrote them as files of a single, empty line. POSIX.1-2008 does not permit this behavior. Historically, ex restored standard output and standard error to their values as of when ex was invoked, before writes to programs were performed. This could disturb the terminal configuration as well as be a security issue for some terminals. POSIX.1-2008 does not permit this, requiring that the program output be captured and displayed as if by the ex print command.Adjust Window
Historically, the line count was set to the value of the scroll option if the type character was end-of-file. This feature was broken on most historical implementations long ago, however, and is not documented anywhere. For this reason, POSIX.1-2008 is resolutely silent. Historically, the z command was <blank>-sensitive and z + and z - did different things than z+ and z- because the type could not be distinguished from a flag. (The commands z . and z = were historically invalid.) POSIX.1-2008 requires conformance to this historical practice. Historically, the z command was further <blank>-sensitive in that the count could not be <blank>-delimited; for example, the commands z= 5 and z- 5 were also invalid. Because the count is not ambiguous with respect to either the type character or the flags, this is not permitted by POSIX.1-2008.Escape
Historically, ex filter commands only read the standard output of the commands, letting standard error appear on the terminal as usual. The vi utility, however, read both standard output and standard error. POSIX.1-2008 requires the latter behavior for both ex and vi, for consistency.Shift Left and Shift Right
Historically, it was possible to add shift characters to increase the effect of the command; for example, <<< outdented (or >>> indented) the lines 3 levels of indentation instead of the default 1. POSIX.1-2008 requires conformance to historical practice.<control>-D
Historically, the <control>-D command erased the prompt, providing the user with an unbroken presentation of lines from the edit buffer. This is not required by POSIX.1-2008; implementations are encouraged to provide it if possible. Historically, the <control>-D command took, and then ignored, a count. POSIX.1-2008 does not permit this behavior.Write Line Number
Historically, the ex = command, when executed in ex mode in an empty edit buffer, reported 0, and from open or visual mode, reported 1. For consistency and simplicity of specification, POSIX.1-2008 does not permit this behavior.Execute
Historically, ex did not correctly handle the inclusion of text input commands (that is, append, insert, and change) in executed buffers. POSIX.1-2008 does not permit this exclusion for consistency. Historically, the logical contents of the buffer being executed did not change if the buffer itself were modified by the commands being executed; that is, buffer execution did not support self-modifying code. POSIX.1-2008 requires conformance to historical practice. Historically, the @ command took a range of lines, and the @ buffer was executed once per line, with the current line ('.') set to each specified line. POSIX.1-2008 requires conformance to historical practice. Some historical implementations did not notice if errors occurred during buffer execution. This, coupled with the ability to specify a range of lines for the ex @ command, makes it trivial to cause them to drop core. POSIX.1-2008 requires that implementations stop buffer execution if any error occurs, if the specified line doesn't exist, or if the contents of the edit buffer itself are replaced (for example, the buffer executes the ex :edit command).Regular Expressions in ex
Historical practice is that the characters in the replacement part of the last s command---that is, those matched by entering a '~' in the regular expression---were not further expanded by the regular expression engine. So, if the characters contained the string dqa.,dq they would match 'a' followed by dq.,dq and not 'a' followed by any character. POSIX.1-2008 requires conformance to historical practice.Edit Options in ex
The following paragraphs describe the historical behavior of some edit options that were not, for whatever reason, included in POSIX.1-2008. Implementations are strongly encouraged to only use these names if the functionality described here is fully supported.- extended
- The extended edit option has been used in some implementations of vi to provide extended regular expressions instead of basic regular expressions This option was omitted from POSIX.1-2008 because it is not widespread historical practice.
- flash
- The flash edit option historically caused the screen to flash instead of beeping on error. This option was omitted from POSIX.1-2008 because it is not found in some historical implementations.
- hardtabs
- The hardtabs edit option historically defined the number of columns between hardware tab settings. This option was omitted from POSIX.1-2008 because it was believed to no longer be generally useful.
- modeline
- The modeline (sometimes named modelines) edit option historically caused ex or vi to read the five first and last lines of the file for editor commands. This option is a security problem, and vendors are strongly encouraged to delete it from historical implementations.
- open
- The open edit option historically disallowed the ex open and visual commands. This edit option was omitted because these commands are required by POSIX.1-2008.
- optimize
- The optimize edit option historically expedited text throughput by setting the terminal to not do automatic <carriage-return> characters when printing more than one logical line of output. This option was omitted from POSIX.1-2008 because it was intended for terminals without addressable cursors, which are rarely, if ever, still used.
- ruler
- The ruler edit option has been used in some implementations of vi to present a current row/column ruler for the user. This option was omitted from POSIX.1-2008 because it is not widespread historical practice.
- sourceany
- The sourceany edit option historically caused ex or vi to source start-up files that were owned by users other than the user running the editor. This option is a security problem, and vendors are strongly encouraged to remove it from their implementations.
- timeout
- The timeout edit option historically enabled the (now standard) feature of only waiting for a short period before returning keys that could be part of a macro. This feature was omitted from POSIX.1-2008 because its behavior is now standard, it is not widely useful, and it was rarely documented.
- verbose
- The verbose edit option has been used in some implementations of vi to cause vi to output error messages for common errors; for example, attempting to move the cursor past the beginning or end of the line instead of only alerting the screen. (The historical vi only alerted the terminal and presented no message for such errors. The historical editor option terse did not select when to present error messages, it only made existing error messages more or less verbose.) This option was omitted from POSIX.1-2008 because it is not widespread historical practice; however, implementors are encouraged to use it if they wish to provide error messages for naive users.
- wraplen
- The wraplen edit option has been used in some implementations of vi to specify an automatic margin measured from the left margin instead of from the right margin. This is useful when multiple screen sizes are being used to edit a single file. This option was omitted from POSIX.1-2008 because it is not widespread historical practice; however, implementors are encouraged to use it if they add this functionality.
autoindent, ai
Historically, the command 0a did not do any autoindentation, regardless of the current indentation of line 1. POSIX.1-2008 requires that any indentation present in line 1 be used.autoprint, ap
Historically, the autoprint edit option was not completely consistent or based solely on modifications to the edit buffer. Exceptions were the read command (when reading from a file, but not from a filter), the append, change, insert, global, and v commands, all of which were not affected by autoprint, and the tag command, which was affected by autoprint. POSIX.1-2008 requires conformance to historical practice. Historically, the autoprint option only applied to the last of multiple commands entered using <vertical-line> delimiters; for example, delete <newline> was affected by autoprint, but delete|version <newline> was not. POSIX.1-2008 requires conformance to historical practice.autowrite, aw
Appending the '!' character to the ex next command to avoid performing an automatic write was not supported in historical implementations. POSIX.1-2008 requires that the behavior match the other ex commands for consistency.ignorecase, ic
Historical implementations of case-insensitive matching (the ignorecase edit option) lead to counter-intuitive situations when uppercase characters were used in range expressions. Historically, the process was as follows:- 1.
- Take a line of text from the edit buffer.
- 2.
- Convert uppercase to lowercase in text line.
- 3.
- Convert uppercase to lowercase in regular expressions, except in character class specifications.
- 4.
-
Match regular expressions against text.
This would mean that, with
ignorecase
in effect, the text:
-
The cat sat on the mat
-
/^the/
-
/^[A-Z]he/
-
paragraphs, para
The ISO POSIX-2:1993 standard made the default paragraphs and sections edit options implementation-defined, arguing they were historically oriented to the UNIX system troff text formatter, and a ``portable user'' could use the {, }, [[, ]], (, and ) commands in open or visual mode and have the cursor stop in unexpected places. POSIX.1-2008 specifies their values in the POSIX locale because the unusual grouping (they only work when grouped into two characters at a time) means that they cannot be used for general-purpose movement, regardless.readonly
Implementations are encouraged to provide the best possible information to the user as to the read-only status of the file, with the exception that they should not consider the current special privileges of the process. This provides users with a safety net because they must force the overwrite of read-only files, even when running with additional privileges. The readonly edit option specification largely conforms to historical practice. The only difference is that historical implementations did not notice that the user had set the readonly edit option in cases where the file was already marked read-only for some reason, and would therefore reinitialize the readonly edit option the next time the contents of the edit buffer were replaced. This behavior is disallowed by POSIX.1-2008.report
The requirement that lines copied to a buffer interact differently than deleted lines is historical practice. For example, if the report edit option is set to 3, deleting 3 lines will cause a report to be written, but 4 lines must be copied before a report is written. The requirement that the ex global, v, open, undo, and visual commands present reports based on the total number of lines added or deleted during the command execution, and that commands executed by the global and v commands not present reports, is historical practice. POSIX.1-2008 extends historical practice by requiring that buffer execution be treated similarly. The reasons for this are two-fold. Historically, only the report by the last command executed from the buffer would be seen by the user, as each new report would overwrite the last. In addition, the standard developers believed that buffer execution had more in common with global and v commands than it did with other ex commands, and should behave similarly, for consistency and simplicity of specification.showmatch, sm
The length of time the cursor spends on the matching character is unspecified because the timing capabilities of systems are often inexact and variable. The time should be long enough for the user to notice, but not long enough for the user to become annoyed. Some implementations of vi have added a matchtime option that permits users to set the number of 0,1 second intervals the cursor pauses on the matching character.showmode
The showmode option has been used in some historical implementations of ex and vi to display the current editing mode when in open or visual mode. The editing modes have generally included ``command'' and ``input'', and sometimes other modes such as ``replace'' and ``change''. The string was usually displayed on the bottom line of the screen at the far right-hand corner. In addition, a preceding '*' character often denoted whether the contents of the edit buffer had been modified. The latter display has sometimes been part of the showmode option, and sometimes based on another option. This option was not available in the 4 BSD historical implementation of vi, but was viewed as generally useful, particularly to novice users, and is required by POSIX.1-2008. The smd shorthand for the showmode option was not present in all historical implementations of the editor. POSIX.1-2008 requires it, for consistency. Not all historical implementations of the editor displayed a mode string for command mode, differentiating command mode from text input mode by the absence of a mode string. POSIX.1-2008 permits this behavior for consistency with historical practice, but implementations are encouraged to provide a display string for both modes.slowopen
Historically, the slowopen option was automatically set if the terminal baud rate was less than 1200 baud, or if the baud rate was 1200 baud and the redraw option was not set. The slowopen option had two effects. First, when inserting characters in the middle of a line, characters after the cursor would not be pushed ahead, but would appear to be overwritten. Second, when creating a new line of text, lines after the current line would not be scrolled down, but would appear to be overwritten. In both cases, ending text input mode would cause the screen to be refreshed to match the actual contents of the edit buffer. Finally, terminals that were sufficiently intelligent caused the editor to ignore the slowopen option. POSIX.1-2008 permits most historical behavior, extending historical practice to require slowopen behaviors if the edit option is set by the user.tags
The default path for tags files is left unspecified as implementations may have their own tags implementations that do not correspond to the historical ones. The default tags option value should probably at least include the file ./tags.term
Historical implementations of ex and vi ignored changes to the term edit option after the initial terminal information was loaded. This is permitted by POSIX.1-2008; however, implementations are encouraged to permit the user to modify their terminal type at any time.terse
Historically, the terse edit option optionally provided a shorter, less descriptive error message, for some error messages. This is permitted, but not required, by POSIX.1-2008. Historically, most common visual mode errors (for example, trying to move the cursor past the end of a line) did not result in an error message, but simply alerted the terminal. Implementations wishing to provide messages for novice users are urged to do so based on the edit option verbose, and not terse.window
In historical implementations, the default for the window edit option was based on the baud rate as follows:- 1.
-
If the baud rate was less than 1200, the
edit
option
w300
set the window value; for example, the line:
-
-
set w300=12
-
-
- 2.
- If the baud rate was equal to 1200, the edit option w1200 set the window value.
- 3.
- If the baud rate was greater than 1200, the edit option w9600 set the window value. The w300, w1200, and w9600 options do not appear in POSIX.1-2008 because of their dependence on specific baud rates. In historical implementations, the size of the window displayed by various commands was related to, but not necessarily the same as, the window edit option. For example, the size of the window was set by the ex command visual 10, but it did not change the value of the window edit option. However, changing the value of the window edit option did change the number of lines that were displayed when the screen was repainted. POSIX.1-2008 does not permit this behavior in the interests of consistency and simplicity of specification, and requires that all commands that change the number of lines that are displayed do it by setting the value of the window edit option.
wrapmargin, wm
Historically, the wrapmargin option did not affect maps inserting characters that also had associated counts; for example :map K 5aABC DEF. Unfortunately, there are widely used maps that depend on this behavior. For consistency and simplicity of specification, POSIX.1-2008 does not permit this behavior. Historically, wrapmargin was calculated using the column display width of all characters on the screen. For example, an implementation using dq^Idq to represent <tab> characters when the list edit option was set, where '^' and 'I' each took up a single column on the screen, would calculate the wrapmargin based on a value of 2 for each <tab>. The number edit option similarly changed the effective length of the line as well. POSIX.1-2008 requires conformance to historical practice. Earlier versions of this standard allowed for implementations with bytes other than eight bits, but this has been modified in this version.FUTURE DIRECTIONS
None.SEE ALSO
Section 2.9.1.1, Command Search and Execution, ctags, ed, sed, sh, stty, vi The Base Definitions volume of POSIX.1-2008, Table 5-1, Escape Sequences and Associated Actions, Chapter 8, Environment Variables, Section 9.3, Basic Regular Expressions, Section 12.2, Utility Syntax Guidelines The System Interfaces volume of POSIX.1-2008, access()COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at www.unix.org/online.html .Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see www.kernel.org/doc/man-pages/reporting_bugs.html .