NAMEread - One line is read from the standard input, or from the file descriptor fd supplied as an argument to the -u option, split into words as...
read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout] [-u fd] [name ...]
One line is read from the standard input, or from the file descriptor fd supplied as an argument to the -u option, split into words as described above under Word Splitting, and the first word is assigned to the first name, the second word to the second name, and so on. If there are more words than names, the remaining words and their intervening delimiters are assigned to the last name. If there are fewer words read from the input stream than names, the remaining names are assigned empty values. The characters in IFS are used to split the line into words using the same rules the shell uses for expansion (described above under Word Splitting). The backslash character (\) may be used to remove any special meaning for the next character read and for line continuation. Options, if supplied, have the following meanings:
The words are assigned to sequential indices of the array variable aname, starting at 0. aname is unset before any new values are assigned. Other name arguments are ignored.
The first character of delim is used to terminate the input line, rather than newline.
-e If the standard input is coming from a terminal, readline (see READLINE above) is used to obtain the line. Readline uses the current (or default, if line editing was not previously active) editing settings.
If readline is being used to read the line, text is placed into the editing buffer before editing begins.
read returns after reading nchars characters rather than waiting for a complete line of input, but honors a delimiter if fewer than nchars characters are read before the delimiter.
read returns after reading exactly nchars characters rather than waiting for a complete line of input, unless EOF is encountered or read times out. Delimiter characters encountered in the input are not treated specially and do not cause read to return until nchars characters are read. The result is not split on the characters in IFS; the intent is that the variable is assigned exactly the characters read (with the exception of backslash; see the -r option below).
Display prompt on standard error, without a trailing newline, before attempting to read any input. The prompt is displayed only if input is coming from a terminal.
-r Backslash does not act as an escape character. The backslash is considered to be part of the line. In particular, a backslash-newline pair may not be used as a line continuation.
-s Silent mode. If input is coming from a terminal, characters are not echoed.
Cause read to time out and return failure if a complete line of input (or a specified number of characters) is not read within timeout seconds. timeout may be a decimal number with a fractional portion following the decimal point. This option is only effective if read is reading input from a terminal, pipe, or other special file; it has no effect when reading from regular files. If read times out, read saves any partial input read into the specified variable name. If timeout is 0, read returns immediately, without trying to read any data. The exit status is 0 if input is available on the specified file descriptor, non-zero otherwise. The exit status is greater than 128 if the timeout is exceeded.
-u fd Read input from file descriptor fd.
If no names are supplied, the line read is assigned to the variable REPLY. The exit status is zero, unless end-of-file is encountered, read times out (in which case the status is greater than 128), a variable assignment error (such as assigning to a readonly variable) occurs, or an invalid file descriptor is supplied as the argument to -u.
This is extracted from the main bash man page, see there for more details.