POSIX (3)

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NAME

POSIX - Perl interface to IEEE Std 1003.1

SYNOPSIS

    use POSIX ();
    use POSIX qw(setsid);
    use POSIX qw(:errno_h :fcntl_h);

    printf "EINTR is %d\n", EINTR;

    $sess_id = POSIX::setsid();

    $fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644);
        # note: that's a filedescriptor, *NOT* a filehandle

DESCRIPTION

The module permits you to access all (or nearly all) the standard identifiers. Many of these identifiers have been given Perl-ish interfaces.

This document gives a condensed list of the features available in the

module. Consult your operating system's manpages for general information on most features. Consult perlfunc for functions which are noted as being identical to Perl's builtin functions.

The first section describes

functions from the 1003.1 specification. The second section describes some classes for signal objects, objects, and other miscellaneous objects. The remaining sections list various constants and macros in an organization which roughly follows Std 1003.1b-1993.

CAVEATS

Everything is exported by default (with a handful of exceptions). This is an unfortunate backwards compatibility feature and its use is strongly discouraged. You should either prevent the exporting (by saying "use POSIX ();", as usual) and then use fully qualified names (e.g. "POSIX::SEEK_END"), or give an explicit import list. If you do neither and opt for the default (as in "use POSIX;"), you will import hundreds and hundreds of symbols into your namespace.

A few functions are not implemented because they are C specific. If you attempt to call these, they will print a message telling you that they aren't implemented, and suggest using the Perl equivalent, should one exist. For example, trying to access the "setjmp()" call will elicit the message ""setjmp() is C-specific: use eval {} instead"".

Furthermore, some evil vendors will claim 1003.1 compliance, but in fact are not so: they will not pass the

( Compliance Test Suites). For example, one vendor may not define "EDEADLK", or the semantics of the errno values set by open(2) might not be quite right. Perl does not attempt to verify compliance. That means you can currently successfully say ``use and then later in your program you find that your vendor has been lax and there's no usable "ICANON" macro after all. This could be construed to be a bug.

FUNCTIONS

_exit

This is identical to the C function "_exit()". It exits the program immediately which means among other things buffered I/O is not flushed.

Note that when using threads and in Linux this is not a good way to exit a thread because in Linux processes and threads are kind of the same thing (Note: while this is the situation in early 2003 there are projects under way to have threads with more POSIXly semantics in Linux). If you want not to return from a thread, detach the thread.

abort

This is identical to the C function "abort()". It terminates the process with a "SIGABRT" signal unless caught by a signal handler or if the handler does not return normally (it e.g. does a "longjmp").

abs

This is identical to Perl's builtin "abs()" function, returning the absolute value of its numerical argument.

access

Determines the accessibility of a file.

        if( POSIX::access( "/", &POSIX::R_OK ) ){
                print "have read permission\n";
        }

Returns "undef" on failure. Note: do not use "access()" for security purposes. Between the "access()" call and the operation you are preparing for the permissions might change: a classic race condition.

acos

This is identical to the C function "acos()", returning the arcus cosine of its numerical argument. See also Math::Trig.

acosh

This is identical to the C function "acosh()", returning the hyperbolic arcus cosine of its numerical argument [C99]. See also Math::Trig.

alarm

This is identical to Perl's builtin "alarm()" function, either for arming or disarming the "SIGARLM" timer.

asctime

This is identical to the C function "asctime()". It returns a string of the form

        "Fri Jun  2 18:22:13 2000\n\0"

and it is called thusly

        $asctime = asctime($sec, $min, $hour, $mday, $mon,
                           $year, $wday, $yday, $isdst);

The $mon is zero-based: January equals 0. The $year is 1900-based: 2001 equals 101. $wday and $yday default to zero (and are usually ignored anyway), and $isdst defaults to -1.

asin

This is identical to the C function "asin()", returning the arcus sine of its numerical argument. See also Math::Trig.

asinh

This is identical to the C function "asinh()", returning the hyperbolic arcus sine of its numerical argument [C99]. See also Math::Trig.

assert

Unimplemented, but you can use ``die'' in perlfunc and the Carp module to achieve similar things.

atan

This is identical to the C function "atan()", returning the arcus tangent of its numerical argument. See also Math::Trig.

atanh

This is identical to the C function "atanh()", returning the hyperbolic arcus tangent of its numerical argument [C99]. See also Math::Trig.

atan2

This is identical to Perl's builtin "atan2()" function, returning the arcus tangent defined by its two numerical arguments, the y coordinate and the x coordinate. See also Math::Trig.

atexit

Not implemented. "atexit()" is C-specific: use "END {}" instead, see perlmod.

atof

Not implemented. "atof()" is C-specific. Perl converts strings to numbers transparently. If you need to force a scalar to a number, add a zero to it.

atoi

Not implemented. "atoi()" is C-specific. Perl converts strings to numbers transparently. If you need to force a scalar to a number, add a zero to it. If you need to have just the integer part, see ``int'' in perlfunc.

atol

Not implemented. "atol()" is C-specific. Perl converts strings to numbers transparently. If you need to force a scalar to a number, add a zero to it. If you need to have just the integer part, see ``int'' in perlfunc.

bsearch

"bsearch()" not supplied. For doing binary search on wordlists, see Search::Dict.

calloc

Not implemented. "calloc()" is C-specific. Perl does memory management transparently.

cbrt

The cube root [C99].

ceil

This is identical to the C function "ceil()", returning the smallest integer value greater than or equal to the given numerical argument.

chdir

This is identical to Perl's builtin "chdir()" function, allowing one to change the working (default) directory, see ``chdir'' in perlfunc.

chmod

This is identical to Perl's builtin "chmod()" function, allowing one to change file and directory permissions, see ``chmod'' in perlfunc.

chown

This is identical to Perl's builtin "chown()" function, allowing one to change file and directory owners and groups, see ``chown'' in perlfunc.

clearerr

Not implemented. Use the method "IO::Handle::clearerr()" instead, to reset the error state (if any) and

EOF

state (if any) of the given stream.

clock

This is identical to the C function "clock()", returning the amount of spent processor time in microseconds.

close

Close the file. This uses file descriptors such as those obtained by calling "POSIX::open".

        $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
        POSIX::close( $fd );

Returns "undef" on failure.

See also ``close'' in perlfunc.

closedir

This is identical to Perl's builtin "closedir()" function for closing a directory handle, see ``closedir'' in perlfunc.

cos

This is identical to Perl's builtin "cos()" function, for returning the cosine of its numerical argument, see ``cos'' in perlfunc. See also Math::Trig.

cosh

This is identical to the C function "cosh()", for returning the hyperbolic cosine of its numeric argument. See also Math::Trig.

copysign

Returns "x" but with the sign of "y" [C99].

 $x_with_sign_of_y = POSIX::copysign($x, $y);

See also ``signbit''.

creat

Create a new file. This returns a file descriptor like the ones returned by "POSIX::open". Use "POSIX::close" to close the file.

        $fd = POSIX::creat( "foo", 0611 );
        POSIX::close( $fd );

See also ``sysopen'' in perlfunc and its "O_CREAT" flag.

ctermid

Generates the path name for the controlling terminal.

        $path = POSIX::ctermid();

ctime

This is identical to the C function "ctime()" and equivalent to "asctime(localtime(...))", see ``asctime'' and ``localtime''.

cuserid

Get the login name of the owner of the current process.

        $name = POSIX::cuserid();

difftime

This is identical to the C function "difftime()", for returning the time difference (in seconds) between two times (as returned by "time()"), see ``time''.

div

Not implemented. "div()" is C-specific, use ``int'' in perlfunc on the usual "/" division and the modulus "%".

dup

This is similar to the C function "dup()", for duplicating a file descriptor.

This uses file descriptors such as those obtained by calling "POSIX::open".

Returns "undef" on failure.

dup2

This is similar to the C function "dup2()", for duplicating a file descriptor to an another known file descriptor.

This uses file descriptors such as those obtained by calling "POSIX::open".

Returns "undef" on failure.

erf

The error function [C99].

erfc

The complementary error function [C99].

errno

Returns the value of errno.

        $errno = POSIX::errno();

This identical to the numerical values of the $!, see ``$ERRNO'' in perlvar.

execl

Not implemented. "execl()" is C-specific, see ``exec'' in perlfunc.

execle

Not implemented. "execle()" is C-specific, see ``exec'' in perlfunc.

execlp

Not implemented. "execlp()" is C-specific, see ``exec'' in perlfunc.

execv

Not implemented. "execv()" is C-specific, see ``exec'' in perlfunc.

execve

Not implemented. "execve()" is C-specific, see ``exec'' in perlfunc.

execvp

Not implemented. "execvp()" is C-specific, see ``exec'' in perlfunc.

exit

This is identical to Perl's builtin "exit()" function for exiting the program, see ``exit'' in perlfunc.

exp

This is identical to Perl's builtin "exp()" function for returning the exponent (e-based) of the numerical argument, see ``exp'' in perlfunc.

expm1

Equivalent to "exp(x) - 1", but more precise for small argument values [C99].

See also ``log1p''.

fabs

This is identical to Perl's builtin "abs()" function for returning the absolute value of the numerical argument, see ``abs'' in perlfunc.

fclose

Not implemented. Use method "IO::Handle::close()" instead, or see ``close'' in perlfunc.

fcntl

This is identical to Perl's builtin "fcntl()" function, see ``fcntl'' in perlfunc.

fdopen

Not implemented. Use method "IO::Handle::new_from_fd()" instead, or see ``open'' in perlfunc.

feof

Not implemented. Use method "IO::Handle::eof()" instead, or see ``eof'' in perlfunc.

ferror

Not implemented. Use method "IO::Handle::error()" instead.

fflush

Not implemented. Use method "IO::Handle::flush()" instead. See also ""$OUTPUT_AUTOFLUSH" in perlvar".

fgetc

Not implemented. Use method "IO::Handle::getc()" instead, or see ``read'' in perlfunc.

fgetpos

Not implemented. Use method "IO::Seekable::getpos()" instead, or see ``seek'' in perlfunc.

fgets

Not implemented. Use method "IO::Handle::gets()" instead. Similar to <>, also known as ``readline'' in perlfunc.

fileno

Not implemented. Use method "IO::Handle::fileno()" instead, or see ``fileno'' in perlfunc.

floor

This is identical to the C function "floor()", returning the largest integer value less than or equal to the numerical argument.

fdim

``Positive difference'', "x - y" if "x > y", zero otherwise [C99].

fegetround

Returns the current floating point rounding mode, one of

  FE_TONEAREST FE_TOWARDZERO FE_UPWARD FE_UPWARD

"FE_TONEAREST" is like ``round'', "FE_TOWARDZERO" is like ``trunc'' [C99].

fesetround

Sets the floating point rounding mode, see ``fegetround'' [C99].

fma

``Fused multiply-add'', "x * y + z", possibly faster (and less lossy) than the explicit two operations [C99].

 my $fused = POSIX::fma($x, $y, $z);

fmax

Maximum of "x" and "y", except when either is "NaN", returns the other [C99].

 my $min = POSIX::fmax($x, $y);

fmin

Minimum of "x" and "y", except when either is "NaN", returns the other [C99].

 my $min = POSIX::fmin($x, $y);

fmod

This is identical to the C function "fmod()".

        $r = fmod($x, $y);

It returns the remainder "$r = $x - $n*$y", where "$n = trunc($x/$y)". The $r has the same sign as $x and magnitude (absolute value) less than the magnitude of $y.

fopen

Not implemented. Use method "IO::File::open()" instead, or see ``open'' in perlfunc.

fork

This is identical to Perl's builtin "fork()" function for duplicating the current process, see ``fork'' in perlfunc and perlfork if you are in Windows.

fpathconf

Retrieves the value of a configurable limit on a file or directory. This uses file descriptors such as those obtained by calling "POSIX::open".

The following will determine the maximum length of the longest allowable pathname on the filesystem which holds /var/foo.

        $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
        $path_max = POSIX::fpathconf($fd, &POSIX::_PC_PATH_MAX);

Returns "undef" on failure.

fpclassify

Returns one of

  FP_NORMAL FP_ZERO FP_SUBNORMAL FP_INFINITE FP_NAN

telling the class of the argument [C99]. "FP_INFINITE" is positive or negative infinity, "FP_NAN" is not-a-number. "FP_SUBNORMAL" means subnormal numbers (also known as denormals), very small numbers with low precision. "FP_ZERO" is zero. "FP_NORMAL" is all the rest.

fprintf

Not implemented. "fprintf()" is C-specific, see ``printf'' in perlfunc instead.

fputc

Not implemented. "fputc()" is C-specific, see ``print'' in perlfunc instead.

fputs

Not implemented. "fputs()" is C-specific, see ``print'' in perlfunc instead.

fread

Not implemented. "fread()" is C-specific, see ``read'' in perlfunc instead.

free

Not implemented. "free()" is C-specific. Perl does memory management transparently.

freopen

Not implemented. "freopen()" is C-specific, see ``open'' in perlfunc instead.

frexp

Return the mantissa and exponent of a floating-point number.

        ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );

fscanf

Not implemented. "fscanf()" is C-specific, use <> and regular expressions instead.

fseek

Not implemented. Use method "IO::Seekable::seek()" instead, or see ``seek'' in perlfunc.

fsetpos

Not implemented. Use method "IO::Seekable::setpos()" instead, or seek ``seek'' in perlfunc.

fstat

Get file status. This uses file descriptors such as those obtained by calling "POSIX::open". The data returned is identical to the data from Perl's builtin "stat" function.

        $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
        @stats = POSIX::fstat( $fd );

fsync

Not implemented. Use method "IO::Handle::sync()" instead.

ftell

Not implemented. Use method "IO::Seekable::tell()" instead, or see ``tell'' in perlfunc.

fwrite

Not implemented. "fwrite()" is C-specific, see ``print'' in perlfunc instead.

getc

This is identical to Perl's builtin "getc()" function, see ``getc'' in perlfunc.

getchar

Returns one character from

STDIN.

Identical to Perl's "getc()", see ``getc'' in perlfunc.

getcwd

Returns the name of the current working directory. See also Cwd.

getegid

Returns the effective group identifier. Similar to Perl' s builtin variable $(, see ``$EGID'' in perlvar.

getenv

Returns the value of the specified environment variable. The same information is available through the %ENV array.

geteuid

Returns the effective user identifier. Identical to Perl's builtin $> variable, see ``$EUID'' in perlvar.

getgid

Returns the user's real group identifier. Similar to Perl's builtin variable $), see ``$GID'' in perlvar.

getgrgid

This is identical to Perl's builtin "getgrgid()" function for returning group entries by group identifiers, see ``getgrgid'' in perlfunc.

getgrnam

This is identical to Perl's builtin "getgrnam()" function for returning group entries by group names, see ``getgrnam'' in perlfunc.

getgroups

Returns the ids of the user's supplementary groups. Similar to Perl's builtin variable $), see ``$GID'' in perlvar.

getlogin

This is identical to Perl's builtin "getlogin()" function for returning the user name associated with the current session, see ``getlogin'' in perlfunc.

getpgrp

This is identical to Perl's builtin "getpgrp()" function for returning the process group identifier of the current process, see ``getpgrp'' in perlfunc.

getpid

Returns the process identifier. Identical to Perl's builtin variable $$, see ``$PID'' in perlvar.

getppid

This is identical to Perl's builtin "getppid()" function for returning the process identifier of the parent process of the current process , see ``getppid'' in perlfunc.

getpwnam

This is identical to Perl's builtin "getpwnam()" function for returning user entries by user names, see ``getpwnam'' in perlfunc.

getpwuid

This is identical to Perl's builtin "getpwuid()" function for returning user entries by user identifiers, see ``getpwuid'' in perlfunc.

gets

Returns one line from "STDIN", similar to <>, also known as the "readline()" function, see ``readline'' in perlfunc.

NOTE

: if you have C programs that still use "gets()", be very afraid. The "gets()" function is a source of endless grief because it has no buffer overrun checks. It should never be used. The "fgets()" function should be preferred instead.

getuid

Returns the user's identifier. Identical to Perl's builtin $< variable, see ``$UID'' in perlvar.

gmtime

This is identical to Perl's builtin "gmtime()" function for converting seconds since the epoch to a date in Greenwich Mean Time, see ``gmtime'' in perlfunc.

hypot

Equivalent to "sqrt(x * x + y * y)" except more stable on very large or very small arguments [C99].

ilogb

Integer binary logarithm [C99]

For example "ilogb(20)" is 4, as an integer.

See also ``logb''.

Inf

The infinity as a constant:

   use POSIX qw(Inf);
   my $pos_inf = +Inf;  # Or just Inf.
   my $neg_inf = -Inf;

See also ``isinf'', and ``fpclassify''.

isalnum

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:alnum:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

You may want to use the "/\w/" construct instead.

isalpha

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:alpha:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

isatty

Returns a boolean indicating whether the specified filehandle is connected to a tty. Similar to the "-t" operator, see ``-X'' in perlfunc.

iscntrl

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:cntrl:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

isdigit

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:digit:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

You may want to use the "/\d/" construct instead.

isfinite

Returns true if the argument is a finite number (that is, not an infinity, or the not-a-number) [C99].

See also ``isinf'', ``isnan'', and ``fpclassify''.

isgraph

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:graph:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

isgreater

(Also "isgreaterequal", "isless", "islessequal", "islessgreater", "isunordered")

Floating point comparisons which handle the "NaN" [C99].

isinf

Returns true if the argument is an infinity (positive or negative) [C99].

See also ``Inf'', ``isnan'', ``isfinite'', and ``fpclassify''.

islower

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:lower:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

Do not use "/[a-z]/" unless you don't care about the current locale.

isnan

Returns true if the argument is "NaN" (not-a-number) [C99].

Note that you cannot test for ""NaN"-ness" with

   $x == $x

since the "NaN" is not equivalent to anything, including itself.

See also ``nan'', ``NaN'', ``isinf'', and ``fpclassify''.

isnormal

Returns true if the argument is normal (that is, not a subnormal/denormal, and not an infinity, or a not-a-number) [C99].

See also ``isfinite'', and ``fpclassify''.

isprint

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:print:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

ispunct

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:punct:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

isspace

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:space:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

You may want to use the "/\s/" construct instead.

isupper

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:upper:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

Do not use "/[A-Z]/" unless you don't care about the current locale.

isxdigit

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against "qr/ ^ [[:xdigit:]]+ $ /x", which you should convert to use instead. The function is deprecated because 1) it doesn't handle

UTF-8

encoded strings properly; and 2) it returns "TRUE" even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see ``Character set modifiers'' in perlre and ``Which character set modifier is in effect?'' in perlre).

The function returns "TRUE" if the input string is empty, or if the corresponding C function returns "TRUE" for every byte in the string.

j0

j1

jn

y0

y1

yn

The Bessel function of the first kind of the order zero.

kill

This is identical to Perl's builtin "kill()" function for sending signals to processes (often to terminate them), see ``kill'' in perlfunc.

labs

Not implemented. (For returning absolute values of long integers.) "labs()" is C-specific, see ``abs'' in perlfunc instead.

lchown

This is identical to the C function, except the order of arguments is consistent with Perl's builtin "chown()" with the added restriction of only one path, not a list of paths. Does the same thing as the "chown()" function but changes the owner of a symbolic link instead of the file the symbolic link points to.

 POSIX::lchown($uid, $gid, $file_path);

ldexp

This is identical to the C function "ldexp()" for multiplying floating point numbers with powers of two.

        $x_quadrupled = POSIX::ldexp($x, 2);

ldiv

Not implemented. (For computing dividends of long integers.) "ldiv()" is C-specific, use "/" and "int()" instead.

lgamma

The logarithm of the Gamma function [C99].

See also ``tgamma''.

log1p

Equivalent to "log(1 + x)", but more stable results for small argument values [C99].

log2

Logarithm base two [C99].

See also ``expm1''.

logb

Integer binary logarithm [C99].

For example "logb(20)" is 4, as a floating point number.

See also ``ilogb''.

link

This is identical to Perl's builtin "link()" function for creating hard links into files, see ``link'' in perlfunc.

localeconv

Get numeric formatting information. Returns a reference to a hash containing the current underlying locale's formatting values. Users of this function should also read perllocale, which provides a comprehensive discussion of Perl locale handling, including a section devoted to this function.

Here is how to query the database for the de (Deutsch or German) locale.

        my $loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
        print "Locale: \"$loc\"\n";
        my $lconv = POSIX::localeconv();
        foreach my $property (qw(
                decimal_point
                thousands_sep
                grouping
                int_curr_symbol
                currency_symbol
                mon_decimal_point
                mon_thousands_sep
                mon_grouping
                positive_sign
                negative_sign
                int_frac_digits
                frac_digits
                p_cs_precedes
                p_sep_by_space
                n_cs_precedes
                n_sep_by_space
                p_sign_posn
                n_sign_posn
                int_p_cs_precedes
                int_p_sep_by_space
                int_n_cs_precedes
                int_n_sep_by_space
                int_p_sign_posn
                int_n_sign_posn
        ))
        {
                printf qq(%s: "%s",\n),
                        $property, $lconv->{$property};
        }

The members whose names begin with "int_p_" and "int_n_" were added by

POSIX.1-2008

and are only available on systems that support them.

localtime

This is identical to Perl's builtin "localtime()" function for converting seconds since the epoch to a date see ``localtime'' in perlfunc.

log

This is identical to Perl's builtin "log()" function, returning the natural (e-based) logarithm of the numerical argument, see ``log'' in perlfunc.

log10

This is identical to the C function "log10()", returning the 10-base logarithm of the numerical argument. You can also use

    sub log10 { log($_[0]) / log(10) }

or

    sub log10 { log($_[0]) / 2.30258509299405 }

or

    sub log10 { log($_[0]) * 0.434294481903252 }

longjmp

Not implemented. "longjmp()" is C-specific: use ``die'' in perlfunc instead.

lseek

Move the file's read/write position. This uses file descriptors such as those obtained by calling "POSIX::open".

        $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
        $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );

Returns "undef" on failure.

lrint

Depending on the current floating point rounding mode, rounds the argument either toward nearest (like ``round''), toward zero (like ``trunc''), downward (toward negative infinity), or upward (toward positive infinity) [C99].

For the rounding mode, see ``fegetround''.

lround

Like ``round'', but as integer, as opposed to floating point [C99].

See also ``ceil'', ``floor'', ``trunc''.

malloc

Not implemented. "malloc()" is C-specific. Perl does memory management transparently.

mblen

This is identical to the C function "mblen()".

Core Perl does not have any support for the wide and multibyte characters of the C standards, except under

UTF-8

locales, so this might be a rather useless function.

However, Perl supports Unicode, see perluniintro.

mbstowcs

This is identical to the C function "mbstowcs()".

See ``mblen''.

mbtowc

This is identical to the C function "mbtowc()".

See ``mblen''.

memchr

Not implemented. "memchr()" is C-specific, see ``index'' in perlfunc instead.

memcmp

Not implemented. "memcmp()" is C-specific, use "eq" instead, see perlop.

memcpy

Not implemented. "memcpy()" is C-specific, use "=", see perlop, or see ``substr'' in perlfunc.

memmove

Not implemented. "memmove()" is C-specific, use "=", see perlop, or see ``substr'' in perlfunc.

memset

Not implemented. "memset()" is C-specific, use "x" instead, see perlop.

mkdir

This is identical to Perl's builtin "mkdir()" function for creating directories, see ``mkdir'' in perlfunc.

mkfifo

This is similar to the C function "mkfifo()" for creating

FIFO

special files.

        if (mkfifo($path, $mode)) { ....

Returns "undef" on failure. The $mode is similar to the mode of "mkdir()", see ``mkdir'' in perlfunc, though for "mkfifo" you must specify the $mode.

mktime

Convert date/time info to a calendar time.

Synopsis:

        mktime(sec, min, hour, mday, mon, year, wday = 0,
               yday = 0, isdst = -1)

The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero, i.e., January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year ("year") is given in years since 1900; i.e., the year 1995 is 95; the year 2001 is 101. Consult your system's "mktime()" manpage for details about these and the other arguments.

Calendar time for December 12, 1995, at 10:30 am.

        $time_t = POSIX::mktime( 0, 30, 10, 12, 11, 95 );
        print "Date = ", POSIX::ctime($time_t);

Returns "undef" on failure.

modf

Return the integral and fractional parts of a floating-point number.

        ($fractional, $integral) = POSIX::modf( 3.14 );

See also ``round''.

NaN

The not-a-number as a constant:

   use POSIX qw(NaN);
   my $nan = NaN;

See also ``nan'', "/isnan", and ``fpclassify''.

nan

Returns not-a-number [C99].

See also ``isnan'' and ``NaN''.

nearbyint

Returns the nearest integer to the argument, according to the current rounding mode (see ``fegetround'') [C99].

nextafter

Returns the next representable floating point number after "x" in the direction of "y" [C99].

 my $nextafter = POSIX::nextafter($x, $y);

Like ``nexttoward'', but potentially less accurate.

nexttoward

Returns the next representable floating point number after "x" in the direction of "y" [C99].

 my $nexttoward = POSIX::nexttoward($x, $y);

Like ``nextafter'', but potentially more accurate.

nice

This is similar to the C function "nice()", for changing the scheduling preference of the current process. Positive arguments mean a more polite process, negative values a more needy process. Normal (non-root) user processes can only change towards being more polite.

Returns "undef" on failure.

offsetof

Not implemented. "offsetof()" is C-specific, you probably want to see ``pack'' in perlfunc instead.

open

Open a file for reading for writing. This returns file descriptors, not Perl filehandles. Use "POSIX::close" to close the file.

Open a file read-only with mode 0666.

        $fd = POSIX::open( "foo" );

Open a file for read and write.

        $fd = POSIX::open( "foo", &POSIX::O_RDWR );

Open a file for write, with truncation.

        $fd = POSIX::open(
                "foo", &POSIX::O_WRONLY | &POSIX::O_TRUNC
        );

Create a new file with mode 0640. Set up the file for writing.

        $fd = POSIX::open(
                "foo", &POSIX::O_CREAT | &POSIX::O_WRONLY, 0640
        );

Returns "undef" on failure.

See also ``sysopen'' in perlfunc.

opendir

Open a directory for reading.

        $dir = POSIX::opendir( "/var" );
        @files = POSIX::readdir( $dir );
        POSIX::closedir( $dir );

Returns "undef" on failure.

pathconf

Retrieves the value of a configurable limit on a file or directory.

The following will determine the maximum length of the longest allowable pathname on the filesystem which holds "/var".

        $path_max = POSIX::pathconf( "/var",
                                      &POSIX::_PC_PATH_MAX );

Returns "undef" on failure.

pause

This is similar to the C function "pause()", which suspends the execution of the current process until a signal is received.

Returns "undef" on failure.

perror

This is identical to the C function "perror()", which outputs to the standard error stream the specified message followed by ": " and the current error string. Use the "warn()" function and the $! variable instead, see ``warn'' in perlfunc and ``$ERRNO'' in perlvar.

pipe

Create an interprocess channel. This returns file descriptors like those returned by "POSIX::open".

        my ($read, $write) = POSIX::pipe();
        POSIX::write( $write, "hello", 5 );
        POSIX::read( $read, $buf, 5 );

See also ``pipe'' in perlfunc.

pow

Computes $x raised to the power $exponent.

        $ret = POSIX::pow( $x, $exponent );

You can also use the "**" operator, see perlop.

printf

Formats and prints the specified arguments to "STDOUT". See also ``printf'' in perlfunc.

putc

Not implemented. "putc()" is C-specific, see ``print'' in perlfunc instead.

putchar

Not implemented. "putchar()" is C-specific, see ``print'' in perlfunc instead.

puts

Not implemented. "puts()" is C-specific, see ``print'' in perlfunc instead.

qsort

Not implemented. "qsort()" is C-specific, see ``sort'' in perlfunc instead.

raise

Sends the specified signal to the current process. See also ``kill'' in perlfunc and the $$ in ``$PID'' in perlvar.

rand

Not implemented. "rand()" is non-portable, see ``rand'' in perlfunc instead.

read

Read from a file. This uses file descriptors such as those obtained by calling "POSIX::open". If the buffer $buf is not large enough for the read then Perl will extend it to make room for the request.

        $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
        $bytes = POSIX::read( $fd, $buf, 3 );

Returns "undef" on failure.

See also ``sysread'' in perlfunc.

readdir

This is identical to Perl's builtin "readdir()" function for reading directory entries, see ``readdir'' in perlfunc.

realloc

Not implemented. "realloc()" is C-specific. Perl does memory management transparently.

remainder

Given "x" and "y", returns the value "x - n*y", where "n" is the integer closest to "x/y". [C99]

 my $remainder = POSIX::remainder($x, $y)

See also ``remquo''.

remove

This is identical to Perl's builtin "unlink()" function for removing files, see ``unlink'' in perlfunc.

remquo

Like ``remainder'' but also returns the low-order bits of the quotient (n) [C99]

(This is quite esoteric interface, mainly used to implement numerical algorithms.)

rename

This is identical to Perl's builtin "rename()" function for renaming files, see ``rename'' in perlfunc.

rewind

Seeks to the beginning of the file.

rewinddir

This is identical to Perl's builtin "rewinddir()" function for rewinding directory entry streams, see ``rewinddir'' in perlfunc.

rint

Identical to ``lrint''.

rmdir

This is identical to Perl's builtin "rmdir()" function for removing (empty) directories, see ``rmdir'' in perlfunc.

round

Returns the integer (but still as floating point) nearest to the argument [C99].

See also ``ceil'', ``floor'', ``lround'', ``modf'', and ``trunc''.

scalbn

Returns "x * 2**y" [C99].

See also ``frexp'' and ``ldexp''.

scanf

Not implemented. "scanf()" is C-specific, use <> and regular expressions instead, see perlre.

setgid

Sets the real group identifier and the effective group identifier for this process. Similar to assigning a value to the Perl's builtin $) variable, see ``$EGID'' in perlvar, except that the latter will change only the real user identifier, and that the setgid() uses only a single numeric argument, as opposed to a space-separated list of numbers.

setjmp

Not implemented. "setjmp()" is C-specific: use "eval {}" instead, see ``eval'' in perlfunc.

setlocale

Modifies and queries the program's underlying locale. Users of this function should read perllocale, whch provides a comprehensive discussion of Perl locale handling, knowledge of which is necessary to properly use this function. It contains a section devoted to this function. The discussion here is merely a summary reference for "setlocale()". Note that Perl itself is almost entirely unaffected by the locale except within the scope of "use locale". (Exceptions are listed in ``Not within the scope of ''use locale"" in perllocale.)

The following examples assume

        use POSIX qw(setlocale LC_ALL LC_CTYPE);

has been issued.

The following will set the traditional

UNIX

system locale behavior (the second argument "C").

        $loc = setlocale( LC_ALL, "C" );

The following will query the current "LC_CTYPE" category. (No second argument means 'query'.)

        $loc = setlocale( LC_CTYPE );

The following will set the "LC_CTYPE" behaviour according to the locale environment variables (the second argument ""). Please see your system's setlocale(3) documentation for the locale environment variables' meaning or consult perllocale.

        $loc = setlocale( LC_CTYPE, "" );

The following will set the "LC_COLLATE" behaviour to Argentinian Spanish.

NOTE

: The naming and availability of locales depends on your operating system. Please consult perllocale for how to find out which locales are available in your system.

        $loc = setlocale( LC_COLLATE, "es_AR.ISO8859-1" );

setpgid

This is similar to the C function "setpgid()" for setting the process group identifier of the current process.

Returns "undef" on failure.

setsid

This is identical to the C function "setsid()" for setting the session identifier of the current process.

setuid

Sets the real user identifier and the effective user identifier for this process. Similar to assigning a value to the Perl's builtin $< variable, see ``$UID'' in perlvar, except that the latter will change only the real user identifier.

sigaction

Detailed signal management. This uses "POSIX::SigAction" objects for the "action" and "oldaction" arguments (the oldaction can also be just a hash reference). Consult your system's "sigaction" manpage for details, see also "POSIX::SigRt".

Synopsis:

        sigaction(signal, action, oldaction = 0)

Returns "undef" on failure. The "signal" must be a number (like "SIGHUP"), not a string (like "SIGHUP"), though Perl does try hard to understand you.

If you use the "SA_SIGINFO" flag, the signal handler will in addition to the first argument, the signal name, also receive a second argument, a hash reference, inside which are the following keys with the following semantics, as defined by POSIX/SUSv3:

    signo       the signal number
    errno       the error number
    code        if this is zero or less, the signal was sent by
                a user process and the uid and pid make sense,
                otherwise the signal was sent by the kernel

The following are also defined by POSIX/SUSv3, but unfortunately not very widely implemented:

    pid         the process id generating the signal
    uid         the uid of the process id generating the signal
    status      exit value or signal for SIGCHLD
    band        band event for SIGPOLL

A third argument is also passed to the handler, which contains a copy of the raw binary contents of the "siginfo" structure: if a system has some non-POSIX fields, this third argument is where to "unpack()" them from.

Note that not all "siginfo" values make sense simultaneously (some are valid only for certain signals, for example), and not all values make sense from Perl perspective, you should to consult your system's "sigaction" and possibly also "siginfo" documentation.

siglongjmp

Not implemented. "siglongjmp()" is C-specific: use ``die'' in perlfunc instead.

signbit

Returns zero for positive arguments, non-zero for negative arguments [C99].

sigpending

Examine signals that are blocked and pending. This uses "POSIX::SigSet" objects for the "sigset" argument. Consult your system's "sigpending" manpage for details.

Synopsis:

        sigpending(sigset)

Returns "undef" on failure.

sigprocmask

Change and/or examine calling process's signal mask. This uses "POSIX::SigSet" objects for the "sigset" and "oldsigset" arguments. Consult your system's "sigprocmask" manpage for details.

Synopsis:

        sigprocmask(how, sigset, oldsigset = 0)

Returns "undef" on failure.

Note that you can't reliably block or unblock a signal from its own signal handler if you're using safe signals. Other signals can be blocked or unblocked reliably.

sigsetjmp

Not implemented. "sigsetjmp()" is C-specific: use "eval {}" instead, see ``eval'' in perlfunc.

sigsuspend

Install a signal mask and suspend process until signal arrives. This uses "POSIX::SigSet" objects for the "signal_mask" argument. Consult your system's "sigsuspend" manpage for details.

Synopsis:

        sigsuspend(signal_mask)

Returns "undef" on failure.

sin

This is identical to Perl's builtin "sin()" function for returning the sine of the numerical argument, see ``sin'' in perlfunc. See also Math::Trig.

sinh

This is identical to the C function "sinh()" for returning the hyperbolic sine of the numerical argument. See also Math::Trig.

sleep

This is functionally identical to Perl's builtin "sleep()" function for suspending the execution of the current for process for certain number of seconds, see ``sleep'' in perlfunc. There is one significant difference, however: "POSIX::sleep()" returns the number of unslept seconds, while the "CORE::sleep()" returns the number of slept seconds.

sprintf

This is similar to Perl's builtin "sprintf()" function for returning a string that has the arguments formatted as requested, see ``sprintf'' in perlfunc.

sqrt

This is identical to Perl's builtin "sqrt()" function. for returning the square root of the numerical argument, see ``sqrt'' in perlfunc.

srand

Give a seed the pseudorandom number generator, see ``srand'' in perlfunc.

sscanf

Not implemented. "sscanf()" is C-specific, use regular expressions instead, see perlre.

stat

This is identical to Perl's builtin "stat()" function for returning information about files and directories.

strcat

Not implemented. "strcat()" is C-specific, use ".=" instead, see perlop.

strchr

Not implemented. "strchr()" is C-specific, see ``index'' in perlfunc instead.

strcmp

Not implemented. "strcmp()" is C-specific, use "eq" or "cmp" instead, see perlop.

strcoll

This is identical to the C function "strcoll()" for collating (comparing) strings transformed using the "strxfrm()" function. Not really needed since Perl can do this transparently, see perllocale.

strcpy

Not implemented. "strcpy()" is C-specific, use "=" instead, see perlop.

strcspn

Not implemented. "strcspn()" is C-specific, use regular expressions instead, see perlre.

strerror

Returns the error string for the specified errno. Identical to the string form of $!, see ``$ERRNO'' in perlvar.

strftime

Convert date and time information to string. Returns the string.

Synopsis:

        strftime(fmt, sec, min, hour, mday, mon, year,
                 wday = -1, yday = -1, isdst = -1)

The month ("mon"), weekday ("wday"), and yearday ("yday") begin at zero, i.e., January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The year ("year") is given in years since 1900, i.e., the year 1995 is 95; the year 2001 is 101. Consult your system's "strftime()" manpage for details about these and the other arguments.

If you want your code to be portable, your format ("fmt") argument should use only the conversion specifiers defined by the

ANSI C

standard (C89, to play safe). These are "aAbBcdHIjmMpSUwWxXyYZ%". But even then, the results of some of the conversion specifiers are non-portable. For example, the specifiers "aAbBcpZ" change according to the locale settings of the user, and both how to set locales (the locale names) and what output to expect are non-standard. The specifier "c" changes according to the timezone settings of the user and the timezone computation rules of the operating system. The "Z" specifier is notoriously unportable since the names of timezones are non-standard. Sticking to the numeric specifiers is the safest route.

The given arguments are made consistent as though by calling "mktime()" before calling your system's "strftime()" function, except that the "isdst" value is not affected.

The string for Tuesday, December 12, 1995.

        $str = POSIX::strftime( "%A, %B %d, %Y",
                                 0, 0, 0, 12, 11, 95, 2 );
        print "$str\n";

strlen

Not implemented. "strlen()" is C-specific, use "length()" instead, see ``length'' in perlfunc.

strncat

Not implemented. "strncat()" is C-specific, use ".=" instead, see perlop.

strncmp

Not implemented. "strncmp()" is C-specific, use "eq" instead, see perlop.

strncpy

Not implemented. "strncpy()" is C-specific, use "=" instead, see perlop.

strpbrk

Not implemented. "strpbrk()" is C-specific, use regular expressions instead, see perlre.

strrchr

Not implemented. "strrchr()" is C-specific, see ``rindex'' in perlfunc instead.

strspn

Not implemented. "strspn()" is C-specific, use regular expressions instead, see perlre.

strstr

This is identical to Perl's builtin "index()" function, see ``index'' in perlfunc.

strtod

String to double translation. Returns the parsed number and the number of characters in the unparsed portion of the string. Truly POSIX-compliant systems set $! ($ERRNO) to indicate a translation error, so clear $! before calling "strtod". However, non-POSIX systems may not check for overflow, and therefore will never set $!.

"strtod" respects any

POSIX

"setlocale()" "LC_TIME" settings, regardless of whether or not it is called from Perl code that is within the scope of "use locale".

To parse a string $str as a floating point number use

    $! = 0;
    ($num, $n_unparsed) = POSIX::strtod($str);

The second returned item and $! can be used to check for valid input:

    if (($str eq '') || ($n_unparsed != 0) || $!) {
        die "Non-numeric input $str" . ($! ? ": $!\n" : "\n");
    }

When called in a scalar context "strtod" returns the parsed number.

strtok

Not implemented. "strtok()" is C-specific, use regular expressions instead, see perlre, or ``split'' in perlfunc.

strtol

String to (long) integer translation. Returns the parsed number and the number of characters in the unparsed portion of the string. Truly POSIX-compliant systems set $! ($ERRNO) to indicate a translation error, so clear $! before calling "strtol". However, non-POSIX systems may not check for overflow, and therefore will never set $!.

"strtol" should respect any

POSIX

setlocale() settings.

To parse a string $str as a number in some base $base use

    $! = 0;
    ($num, $n_unparsed) = POSIX::strtol($str, $base);

The base should be zero or between 2 and 36, inclusive. When the base is zero or omitted "strtol" will use the string itself to determine the base: a leading ``0x'' or ``0X'' means hexadecimal; a leading ``0'' means octal; any other leading characters mean decimal. Thus, ``1234'' is parsed as a decimal number, ``01234'' as an octal number, and ``0x1234'' as a hexadecimal number.

The second returned item and $! can be used to check for valid input:

    if (($str eq '') || ($n_unparsed != 0) || !$!) {
        die "Non-numeric input $str" . $! ? ": $!\n" : "\n";
    }

When called in a scalar context "strtol" returns the parsed number.

strtold

Like ``strtod'' but for long doubles. Defined only if the system supports long doubles.

strtoul

String to unsigned (long) integer translation. "strtoul()" is identical to "strtol()" except that "strtoul()" only parses unsigned integers. See ``strtol'' for details.

Note: Some vendors supply "strtod()" and "strtol()" but not "strtoul()". Other vendors that do supply "strtoul()" parse ``-1'' as a valid value.

strxfrm

String transformation. Returns the transformed string.

        $dst = POSIX::strxfrm( $src );

Used in conjunction with the "strcoll()" function, see ``strcoll''.

Not really needed since Perl can do this transparently, see perllocale.

sysconf

Retrieves values of system configurable variables.

The following will get the machine's clock speed.

        $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );

Returns "undef" on failure.

system

This is identical to Perl's builtin "system()" function, see ``system'' in perlfunc.

tan

This is identical to the C function "tan()", returning the tangent of the numerical argument. See also Math::Trig.

tanh

This is identical to the C function "tanh()", returning the hyperbolic tangent of the numerical argument. See also Math::Trig.

tcdrain

This is similar to the C function "tcdrain()" for draining the output queue of its argument stream.

Returns "undef" on failure.

tcflow

This is similar to the C function "tcflow()" for controlling the flow of its argument stream.

Returns "undef" on failure.

tcflush

This is similar to the C function "tcflush()" for flushing the I/O buffers of its argument stream.

Returns "undef" on failure.

tcgetpgrp

This is identical to the C function "tcgetpgrp()" for returning the process group identifier of the foreground process group of the controlling terminal.

tcsendbreak

This is similar to the C function "tcsendbreak()" for sending a break on its argument stream.

Returns "undef" on failure.

tcsetpgrp

This is similar to the C function "tcsetpgrp()" for setting the process group identifier of the foreground process group of the controlling terminal.

Returns "undef" on failure.

tgamma

The Gamma function [C99].

See also ``lgamma''.

time

This is identical to Perl's builtin "time()" function for returning the number of seconds since the epoch (whatever it is for the system), see ``time'' in perlfunc.

times

The "times()" function returns elapsed realtime since some point in the past (such as system startup), user and system times for this process, and user and system times used by child processes. All times are returned in clock ticks.

    ($realtime, $user, $system, $cuser, $csystem)
        = POSIX::times();

Note: Perl's builtin "times()" function returns four values, measured in seconds.

tmpfile

Not implemented. Use method "IO::File::new_tmpfile()" instead, or see File::Temp.

tmpnam

Returns a name for a temporary file.

        $tmpfile = POSIX::tmpnam();

For security reasons, which are probably detailed in your system's documentation for the C library "tmpnam()" function, this interface should not be used; instead see File::Temp.

tolower

This is identical to the C function, except that it can apply to a single character or to a whole string, and currently operates as if the locale always is ``C''. Consider using the "lc()" function, see ``lc'' in perlfunc, see ``lc'' in perlfunc, or the equivalent "\L" operator inside doublequotish strings.

toupper

This is similar to the C function, except that it can apply to a single character or to a whole string, and currently operates as if the locale always is ``C''. Consider using the "uc()" function, see ``uc'' in perlfunc, or the equivalent "\U" operator inside doublequotish strings.

trunc

Returns the integer toward zero from the argument [C99].

See also ``ceil'', ``floor'', and ``round''.

ttyname

This is identical to the C function "ttyname()" for returning the name of the current terminal.

tzname

Retrieves the time conversion information from the "tzname" variable.

        POSIX::tzset();
        ($std, $dst) = POSIX::tzname();

tzset

This is identical to the C function "tzset()" for setting the current timezone based on the environment variable "TZ", to be used by "ctime()", "localtime()", "mktime()", and "strftime()" functions.

umask

This is identical to Perl's builtin "umask()" function for setting (and querying) the file creation permission mask, see ``umask'' in perlfunc.

uname

Get name of current operating system.

        ($sysname, $nodename, $release, $version, $machine)
                = POSIX::uname();

Note that the actual meanings of the various fields are not that well standardized, do not expect any great portability. The $sysname might be the name of the operating system, the $nodename might be the name of the host, the $release might be the (major) release number of the operating system, the $version might be the (minor) release number of the operating system, and the $machine might be a hardware identifier. Maybe.

ungetc

Not implemented. Use method "IO::Handle::ungetc()" instead.

unlink

This is identical to Perl's builtin "unlink()" function for removing files, see ``unlink'' in perlfunc.

utime

This is identical to Perl's builtin "utime()" function for changing the time stamps of files and directories, see ``utime'' in perlfunc.

vfprintf

Not implemented. "vfprintf()" is C-specific, see ``printf'' in perlfunc instead.

vprintf

Not implemented. "vprintf()" is C-specific, see ``printf'' in perlfunc instead.

vsprintf

Not implemented. "vsprintf()" is C-specific, see ``sprintf'' in perlfunc instead.

wait

This is identical to Perl's builtin "wait()" function, see ``wait'' in perlfunc.

waitpid

Wait for a child process to change state. This is identical to Perl's builtin "waitpid()" function, see ``waitpid'' in perlfunc.

        $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
        print "status = ", ($? / 256), "\n";

wcstombs

This is identical to the C function "wcstombs()".

See ``mblen''.

wctomb

This is identical to the C function "wctomb()".

See ``mblen''.

write

Write to a file. This uses file descriptors such as those obtained by calling "POSIX::open".

        $fd = POSIX::open( "foo", &POSIX::O_WRONLY );
        $buf = "hello";
        $bytes = POSIX::write( $fd, $buf, 5 );

Returns "undef" on failure.

See also ``syswrite'' in perlfunc.

CLASSES

POSIX::SigAction

new

Creates a new "POSIX::SigAction" object which corresponds to the C "struct sigaction". This object will be destroyed automatically when it is no longer needed. The first parameter is the handler, a sub reference. The second parameter is a "POSIX::SigSet" object, it defaults to the empty set. The third parameter contains the "sa_flags", it defaults to 0.

        $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT);
        $sigaction = POSIX::SigAction->new(
                        \&handler, $sigset, &POSIX::SA_NOCLDSTOP
                     );

This "POSIX::SigAction" object is intended for use with the "POSIX::sigaction()" function.

handler

mask

flags

accessor functions to get/set the values of a SigAction object.

        $sigset = $sigaction->mask;
        $sigaction->flags(&POSIX::SA_RESTART);

safe

accessor function for the ``safe signals'' flag of a SigAction object; see perlipc for general information on safe (a.k.a. ``deferred'') signals. If you wish to handle a signal safely, use this accessor to set the ``safe'' flag in the "POSIX::SigAction" object:

        $sigaction->safe(1);

You may also examine the ``safe'' flag on the output action object which is filled in when given as the third parameter to "POSIX::sigaction()":

        sigaction(SIGINT, $new_action, $old_action);
        if ($old_action->safe) {
            # previous SIGINT handler used safe signals
        }

POSIX::SigRt

%SIGRT

A hash of the

POSIX

realtime signal handlers. It is an extension of the standard %SIG, the $POSIX::SIGRT{SIGRTMIN} is roughly equivalent to $SIG{SIGRTMIN}, but the right

POSIX

moves (see below) are made with the "POSIX::SigSet" and "POSIX::sigaction" instead of accessing the %SIG.

You can set the %POSIX::SIGRT elements to set the

POSIX

realtime signal handlers, use "delete" and "exists" on the elements, and use "scalar" on the %POSIX::SIGRT to find out how many

POSIX

realtime signals there are available "(SIGRTMAX - SIGRTMIN + 1", the "SIGRTMAX" is a valid

POSIX

realtime signal).

Setting the %SIGRT elements is equivalent to calling this:

  sub new {
    my ($rtsig, $handler, $flags) = @_;
    my $sigset = POSIX::SigSet($rtsig);
    my $sigact = POSIX::SigAction->new($handler,$sigset,$flags);
    sigaction($rtsig, $sigact);
  }

The flags default to zero, if you want something different you can either use "local" on $POSIX::SigRt::SIGACTION_FLAGS, or you can derive from POSIX::SigRt and define your own "new()" (the tied hash

STORE

method of the %SIGRT calls "new($rtsig, $handler, $SIGACTION_FLAGS)", where the $rtsig ranges from zero to "SIGRTMAX - SIGRTMIN + 1)".

Just as with any signal, you can use "sigaction($rtsig, undef, $oa)" to retrieve the installed signal handler (or, rather, the signal action).

NOTE:

whether

POSIX

realtime signals really work in your system, or whether Perl has been compiled so that it works with them, is outside of this discussion.

SIGRTMIN

Return the minimum

POSIX

realtime signal number available, or "undef" if no

POSIX

realtime signals are available.

SIGRTMAX

Return the maximum

POSIX

realtime signal number available, or "undef" if no

POSIX

realtime signals are available.

POSIX::SigSet

new

Create a new SigSet object. This object will be destroyed automatically when it is no longer needed. Arguments may be supplied to initialize the set.

Create an empty set.

        $sigset = POSIX::SigSet->new;

Create a set with "SIGUSR1".

        $sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 );

addset

Add a signal to a SigSet object.

        $sigset->addset( &POSIX::SIGUSR2 );

Returns "undef" on failure.

delset

Remove a signal from the SigSet object.

        $sigset->delset( &POSIX::SIGUSR2 );

Returns "undef" on failure.

emptyset

Initialize the SigSet object to be empty.

        $sigset->emptyset();

Returns "undef" on failure.

fillset

Initialize the SigSet object to include all signals.

        $sigset->fillset();

Returns "undef" on failure.

ismember

Tests the SigSet object to see if it contains a specific signal.

        if( $sigset->ismember( &POSIX::SIGUSR1 ) ){
                print "contains SIGUSR1\n";
        }

POSIX::Termios

new

Create a new Termios object. This object will be destroyed automatically when it is no longer needed. A Termios object corresponds to the "termios" C struct. "new()" mallocs a new one, "getattr()" fills it from a file descriptor, and "setattr()" sets a file descriptor's parameters to match Termios' contents.

        $termios = POSIX::Termios->new;

getattr

Get terminal control attributes.

Obtain the attributes for "stdin".

        $termios->getattr( 0 ) # Recommended for clarity.
        $termios->getattr()

Obtain the attributes for stdout.

        $termios->getattr( 1 )

Returns "undef" on failure.

getcc

Retrieve a value from the "c_cc" field of a "termios" object. The "c_cc" field is an array so an index must be specified.

        $c_cc[1] = $termios->getcc(1);

getcflag

Retrieve the "c_cflag" field of a "termios" object.

        $c_cflag = $termios->getcflag;

getiflag

Retrieve the "c_iflag" field of a "termios" object.

        $c_iflag = $termios->getiflag;

getispeed

Retrieve the input baud rate.

        $ispeed = $termios->getispeed;

getlflag

Retrieve the "c_lflag" field of a "termios" object.

        $c_lflag = $termios->getlflag;

getoflag

Retrieve the "c_oflag" field of a "termios" object.

        $c_oflag = $termios->getoflag;

getospeed

Retrieve the output baud rate.

        $ospeed = $termios->getospeed;

setattr

Set terminal control attributes.

Set attributes immediately for stdout.

        $termios->setattr( 1, &POSIX::TCSANOW );

Returns "undef" on failure.

setcc

Set a value in the "c_cc" field of a "termios" object. The "c_cc" field is an array so an index must be specified.

        $termios->setcc( &POSIX::VEOF, 1 );

setcflag

Set the "c_cflag" field of a "termios" object.

        $termios->setcflag( $c_cflag | &POSIX::CLOCAL );

setiflag

Set the "c_iflag" field of a "termios" object.

        $termios->setiflag( $c_iflag | &POSIX::BRKINT );

setispeed

Set the input baud rate.

        $termios->setispeed( &POSIX::B9600 );

Returns "undef" on failure.

setlflag

Set the "c_lflag" field of a "termios" object.

        $termios->setlflag( $c_lflag | &POSIX::ECHO );

setoflag

Set the "c_oflag" field of a "termios" object.

        $termios->setoflag( $c_oflag | &POSIX::OPOST );

setospeed

Set the output baud rate.

        $termios->setospeed( &POSIX::B9600 );

Returns "undef" on failure.

Baud rate values

"B38400" "B75" "B200" "B134" "B300" "B1800" "B150" "B0" "B19200" "B1200" "B9600" "B600" "B4800" "B50" "B2400" "B110"

Terminal interface values

"TCSADRAIN" "TCSANOW" "TCOON" "TCIOFLUSH" "TCOFLUSH" "TCION" "TCIFLUSH" "TCSAFLUSH" "TCIOFF" "TCOOFF"

c_cc field values

"VEOF" "VEOL" "VERASE" "VINTR" "VKILL" "VQUIT" "VSUSP" "VSTART" "VSTOP" "VMIN" "VTIME" "NCCS"

c_cflag field values

"CLOCAL" "CREAD" "CSIZE" "CS5" "CS6" "CS7" "CS8" "CSTOPB" "HUPCL" "PARENB" "PARODD"

c_iflag field values

"BRKINT" "ICRNL" "IGNBRK" "IGNCR" "IGNPAR" "INLCR" "INPCK" "ISTRIP" "IXOFF" "IXON" "PARMRK"

c_lflag field values

"ECHO" "ECHOE" "ECHOK" "ECHONL" "ICANON" "IEXTEN" "ISIG" "NOFLSH" "TOSTOP"

c_oflag field values

"OPOST"

PATHNAME CONSTANTS

Constants

"_PC_CHOWN_RESTRICTED" "_PC_LINK_MAX" "_PC_MAX_CANON" "_PC_MAX_INPUT" "_PC_NAME_MAX" "_PC_NO_TRUNC" "_PC_PATH_MAX" "_PC_PIPE_BUF" "_PC_VDISABLE"

POSIX CONSTANTS

Constants

"_POSIX_ARG_MAX" "_POSIX_CHILD_MAX" "_POSIX_CHOWN_RESTRICTED" "_POSIX_JOB_CONTROL" "_POSIX_LINK_MAX" "_POSIX_MAX_CANON" "_POSIX_MAX_INPUT" "_POSIX_NAME_MAX" "_POSIX_NGROUPS_MAX" "_POSIX_NO_TRUNC" "_POSIX_OPEN_MAX" "_POSIX_PATH_MAX" "_POSIX_PIPE_BUF" "_POSIX_SAVED_IDS" "_POSIX_SSIZE_MAX" "_POSIX_STREAM_MAX" "_POSIX_TZNAME_MAX" "_POSIX_VDISABLE" "_POSIX_VERSION"

SYSTEM CONFIGURATION

Constants

"_SC_ARG_MAX" "_SC_CHILD_MAX" "_SC_CLK_TCK" "_SC_JOB_CONTROL" "_SC_NGROUPS_MAX" "_SC_OPEN_MAX" "_SC_PAGESIZE" "_SC_SAVED_IDS" "_SC_STREAM_MAX" "_SC_TZNAME_MAX" "_SC_VERSION"

ERRNO

Constants

"E2BIG" "EACCES" "EADDRINUSE" "EADDRNOTAVAIL" "EAFNOSUPPORT" "EAGAIN" "EALREADY" "EBADF" "EBADMSG" "EBUSY" "ECANCELED" "ECHILD" "ECONNABORTED" "ECONNREFUSED" "ECONNRESET" "EDEADLK" "EDESTADDRREQ" "EDOM" "EDQUOT" "EEXIST" "EFAULT" "EFBIG" "EHOSTDOWN" "EHOSTUNREACH" "EIDRM" "EILSEQ" "EINPROGRESS" "EINTR" "EINVAL" "EIO" "EISCONN" "EISDIR" "ELOOP" "EMFILE" "EMLINK" "EMSGSIZE" "ENAMETOOLONG" "ENETDOWN" "ENETRESET" "ENETUNREACH" "ENFILE" "ENOBUFS" "ENODATA" "ENODEV" "ENOENT" "ENOEXEC" "ENOLCK" "ENOLINK" "ENOMEM" "ENOMSG" "ENOPROTOOPT" "ENOSPC" "ENOSR" "ENOSTR" "ENOSYS" "ENOTBLK" "ENOTCONN" "ENOTDIR" "ENOTEMPTY" "ENOTRECOVERABLE" "ENOTSOCK" "ENOTSUP" "ENOTTY" "ENXIO" "EOPNOTSUPP" "EOTHER" "EOVERFLOW" "EOWNERDEAD" "EPERM" "EPFNOSUPPORT" "EPIPE" "EPROCLIM" "EPROTO" "EPROTONOSUPPORT" "EPROTOTYPE" "ERANGE" "EREMOTE" "ERESTART" "EROFS" "ESHUTDOWN" "ESOCKTNOSUPPORT" "ESPIPE" "ESRCH" "ESTALE" "ETIME" "ETIMEDOUT" "ETOOMANYREFS" "ETXTBSY" "EUSERS" "EWOULDBLOCK" "EXDEV"

FCNTL

Constants

"FD_CLOEXEC" "F_DUPFD" "F_GETFD" "F_GETFL" "F_GETLK" "F_OK" "F_RDLCK" "F_SETFD" "F_SETFL" "F_SETLK" "F_SETLKW" "F_UNLCK" "F_WRLCK" "O_ACCMODE" "O_APPEND" "O_CREAT" "O_EXCL" "O_NOCTTY" "O_NONBLOCK" "O_RDONLY" "O_RDWR" "O_TRUNC" "O_WRONLY"

FLOAT

Constants

"DBL_DIG" "DBL_EPSILON" "DBL_MANT_DIG" "DBL_MAX" "DBL_MAX_10_EXP" "DBL_MAX_EXP" "DBL_MIN" "DBL_MIN_10_EXP" "DBL_MIN_EXP" "FLT_DIG" "FLT_EPSILON" "FLT_MANT_DIG" "FLT_MAX" "FLT_MAX_10_EXP" "FLT_MAX_EXP" "FLT_MIN" "FLT_MIN_10_EXP" "FLT_MIN_EXP" "FLT_RADIX" "FLT_ROUNDS" "LDBL_DIG" "LDBL_EPSILON" "LDBL_MANT_DIG" "LDBL_MAX" "LDBL_MAX_10_EXP" "LDBL_MAX_EXP" "LDBL_MIN" "LDBL_MIN_10_EXP" "LDBL_MIN_EXP"

FLOATING-POINT ENVIRONMENT

Constants

"FE_DOWNWARD" "FE_TONEAREST" "FE_TOWARDZERO" "FE_UPWARD" on systems that support them.

LIMITS

Constants

"ARG_MAX" "CHAR_BIT" "CHAR_MAX" "CHAR_MIN" "CHILD_MAX" "INT_MAX" "INT_MIN" "LINK_MAX" "LONG_MAX" "LONG_MIN" "MAX_CANON" "MAX_INPUT" "MB_LEN_MAX" "NAME_MAX" "NGROUPS_MAX" "OPEN_MAX" "PATH_MAX" "PIPE_BUF" "SCHAR_MAX" "SCHAR_MIN" "SHRT_MAX" "SHRT_MIN" "SSIZE_MAX" "STREAM_MAX" "TZNAME_MAX" "UCHAR_MAX" "UINT_MAX" "ULONG_MAX" "USHRT_MAX"

LOCALE

Constants

"LC_ALL" "LC_COLLATE" "LC_CTYPE" "LC_MONETARY" "LC_NUMERIC" "LC_TIME" "LC_MESSAGES" on systems that support them.

MATH

Constants

"HUGE_VAL"

"FP_ILOGB0" "FP_ILOGBNAN" "FP_INFINITE" "FP_NAN" "FP_NORMAL" "FP_SUBNORMAL" "FP_ZERO" "INFINITY" "NAN" "Inf" "NaN" "M_1_PI" "M_2_PI" "M_2_SQRTPI" "M_E" "M_LN10" "M_LN2" "M_LOG10E" "M_LOG2E" "M_PI" "M_PI_2" "M_PI_4" "M_SQRT1_2" "M_SQRT2" on systems with C99 support.

SIGNAL

Constants

"SA_NOCLDSTOP" "SA_NOCLDWAIT" "SA_NODEFER" "SA_ONSTACK" "SA_RESETHAND" "SA_RESTART" "SA_SIGINFO" "SIGABRT" "SIGALRM" "SIGCHLD" "SIGCONT" "SIGFPE" "SIGHUP" "SIGILL" "SIGINT" "SIGKILL" "SIGPIPE" "SIGQUIT" "SIGSEGV" "SIGSTOP" "SIGTERM" "SIGTSTP" "SIGTTIN" "SIGTTOU" "SIGUSR1" "SIGUSR2" "SIG_BLOCK" "SIG_DFL" "SIG_ERR" "SIG_IGN" "SIG_SETMASK" "SIG_UNBLOCK"

STAT

Constants

"S_IRGRP" "S_IROTH" "S_IRUSR" "S_IRWXG" "S_IRWXO" "S_IRWXU" "S_ISGID" "S_ISUID" "S_IWGRP" "S_IWOTH" "S_IWUSR" "S_IXGRP" "S_IXOTH" "S_IXUSR"

Macros

"S_ISBLK" "S_ISCHR" "S_ISDIR" "S_ISFIFO" "S_ISREG"

STDLIB

Constants

"EXIT_FAILURE" "EXIT_SUCCESS" "MB_CUR_MAX" "RAND_MAX"

STDIO

Constants

"BUFSIZ" "EOF" "FILENAME_MAX" "L_ctermid" "L_cuserid" "L_tmpname" "TMP_MAX"

TIME

Constants

"CLK_TCK" "CLOCKS_PER_SEC"

UNISTD

Constants

"R_OK" "SEEK_CUR" "SEEK_END" "SEEK_SET" "STDIN_FILENO" "STDOUT_FILENO" "STDERR_FILENO" "W_OK" "X_OK"

WAIT

Constants

"WNOHANG" "WUNTRACED"

WNOHANG

Do not suspend the calling process until a child process changes state but instead return immediately.

WUNTRACED

Catch stopped child processes.

Macros

"WIFEXITED" "WEXITSTATUS" "WIFSIGNALED" "WTERMSIG" "WIFSTOPPED" "WSTOPSIG"

WIFEXITED

"WIFEXITED(${^CHILD_ERROR_NATIVE})" returns true if the child process exited normally ("exit()" or by falling off the end of "main()")

WEXITSTATUS

"WEXITSTATUS(${^CHILD_ERROR_NATIVE})" returns the normal exit status of the child process (only meaningful if "WIFEXITED(${^CHILD_ERROR_NATIVE})" is true)

WIFSIGNALED

"WIFSIGNALED(${^CHILD_ERROR_NATIVE})" returns true if the child process terminated because of a signal

WTERMSIG

"WTERMSIG(${^CHILD_ERROR_NATIVE})" returns the signal the child process terminated for (only meaningful if "WIFSIGNALED(${^CHILD_ERROR_NATIVE})" is true)

WIFSTOPPED

"WIFSTOPPED(${^CHILD_ERROR_NATIVE})" returns true if the child process is currently stopped (can happen only if you specified the

WUNTRACED

flag to "waitpid()")

WSTOPSIG

"WSTOPSIG(${^CHILD_ERROR_NATIVE})" returns the signal the child process was stopped for (only meaningful if "WIFSTOPPED(${^CHILD_ERROR_NATIVE})" is true)