POSIX - Perl interface to IEEE Std 1003.1
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
The POSIX module permits you to access all (or nearly all) the standard
POSIX 1003.1 identifiers. Many of these identifiers have been given Perl-ish
I<Everything is exported by default> with the exception of any POSIX
functions with the same name as a built-in Perl function, such as
C<abs>, C<alarm>, C<rmdir>, C<write>, etc.., which will be exported
only if you ask for them explicitly. This is an unfortunate backwards
compatibility feature. You can stop the exporting by saying C<use
POSIX ()> and then use the fully qualified names (ie. C<POSIX::SEEK_END>).
This document gives a condensed list of the features available in the POSIX
module. Consult your operating system's manpages for general information on
most features. Consult L<perlfunc> for functions which are noted as being
identical to Perl's builtin functions.
The first section describes POSIX functions from the 1003.1 specification.
The second section describes some classes for signal objects, TTY objects,
and other miscellaneous objects. The remaining sections list various
constants and macros in an organization which roughly follows IEEE Std
The POSIX module is probably the most complex Perl module supplied with
the standard distribution. It incorporates autoloading, namespace games,
and dynamic loading of code that's in Perl, C, or both. It's a great
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 PCTS (POSIX 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 POSIX compliance. That means you can currently
successfully say "use POSIX", 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.
This is identical to the C function C<_exit()>. It exits the program
immediately which means among other things buffered I/O is B<not> flushed.
Note that when using threads and in Linux this is B<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.
This is identical to the C function C<abort()>. It terminates the
process with a C<SIGABRT> signal unless caught by a signal handler or
if the handler does not return normally (it e.g. does a C<longjmp>).
This is identical to Perl's builtin C<abs()> function, returning
the absolute value of its numerical argument.
Determines the accessibility of a file.
if( POSIX::access( "/", &POSIX::R_OK ) ){
print "have read permission\n";
Returns C<undef> on failure. Note: do not use C<access()> for
security purposes. Between the C<access()> call and the operation
you are preparing for the permissions might change: a classic
This is identical to the C function C<acos()>, returning
the arcus cosine of its numerical argument. See also L<Math::Trig>.
This is identical to Perl's builtin C<alarm()> function,
either for arming or disarming the C<SIGARLM> timer.
This is identical to the C function C<asctime()>. It returns
"Fri Jun 2 18:22:13 2000\n\0"
$asctime = asctime($sec, $min, $hour, $mday, $mon, $year,
The C<$mon> is zero-based: January equals C<0>. The C<$year> is
1900-based: 2001 equals C<101>. The C<$wday>, C<$yday>, and C<$isdst>
default to zero (and the first two are usually ignored anyway).
This is identical to the C function C<asin()>, returning
the arcus sine of its numerical argument. See also L<Math::Trig>.
Unimplemented, but you can use L<perlfunc/die> and the L<Carp> module
to achieve similar things.
This is identical to the C function C<atan()>, returning the
arcus tangent of its numerical argument. See also L<Math::Trig>.
This is identical to Perl's builtin C<atan2()> function, returning
the arcus tangent defined by its two numerical arguments, the I<y>
coordinate and the I<x> coordinate. See also L<Math::Trig>.
atexit() is C-specific: use C<END {}> instead, see L<perlsub>.
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() 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 L<perlfunc/int>.
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 L<perlfunc/int>.
bsearch() not supplied. For doing binary search on wordlists,
calloc() is C-specific. Perl does memory management transparently.
This is identical to the C function C<ceil()>, returning the smallest
integer value greater than or equal to the given numerical argument.
This is identical to Perl's builtin C<chdir()> function, allowing
one to change the working (default) directory, see L<perlfunc/chdir>.
This is identical to Perl's builtin C<chmod()> function, allowing
one to change file and directory permissions, see L<perlfunc/chmod>.
This is identical to Perl's builtin C<chown()> function, allowing one
to change file and directory owners and groups, see L<perlfunc/chown>.
Use the method C<IO::Handle::clearerr()> instead, to reset the error
state (if any) and EOF state (if any) of the given stream.
This is identical to the C function C<clock()>, returning the
amount of spent processor time in microseconds.
Close the file. This uses file descriptors such as those obtained by calling
$fd = POSIX::open( "foo", &POSIX::O_RDONLY );
Returns C<undef> on failure.
See also L<perlfunc/close>.
This is identical to Perl's builtin C<closedir()> function for closing
a directory handle, see L<perlfunc/closedir>.
This is identical to Perl's builtin C<cos()> function, for returning
the cosine of its numerical argument, see L<perlfunc/cos>.
This is identical to the C function C<cosh()>, for returning
the hyperbolic cosine of its numeric argument. See also L<Math::Trig>.
Create a new file. This returns a file descriptor like the ones returned by
C<POSIX::open>. Use C<POSIX::close> to close the file.
$fd = POSIX::creat( "foo", 0611 );
See also L<perlfunc/sysopen> and its C<O_CREAT> flag.
Generates the path name for the controlling terminal.
$path = POSIX::ctermid();
This is identical to the C function C<ctime()> and equivalent
to C<asctime(localtime(...))>, see L</asctime> and L</localtime>.
Get the login name of the owner of the current process.
$name = POSIX::cuserid();
This is identical to the C function C<difftime()>, for returning
the time difference (in seconds) between two times (as returned
by C<time()>), see L</time>.
div() is C-specific, use L<perlfunc/int> on the usual C</> division and
This is similar to the C function C<dup()>, for duplicating a file
This uses file descriptors such as those obtained by calling
Returns C<undef> on failure.
This is similar to the C function C<dup2()>, for duplicating a file
descriptor to an another known file descriptor.
This uses file descriptors such as those obtained by calling
Returns C<undef> on failure.
Returns the value of errno.
This identical to the numerical values of the C<$!>, see L<perlvar/$ERRNO>.
execl() is C-specific, see L<perlfunc/exec>.
execle() is C-specific, see L<perlfunc/exec>.
execlp() is C-specific, see L<perlfunc/exec>.
execv() is C-specific, see L<perlfunc/exec>.
execve() is C-specific, see L<perlfunc/exec>.
execvp() is C-specific, see L<perlfunc/exec>.
This is identical to Perl's builtin C<exit()> function for exiting the
program, see L<perlfunc/exit>.
This is identical to Perl's builtin C<exp()> function for
returning the exponent (I<e>-based) of the numerical argument,
This is identical to Perl's builtin C<abs()> function for returning
the absolute value of the numerical argument, see L<perlfunc/abs>.
Use method C<IO::Handle::close()> instead, or see L<perlfunc/close>.
This is identical to Perl's builtin C<fcntl()> function,
Use method C<IO::Handle::new_from_fd()> instead, or see L<perlfunc/open>.
Use method C<IO::Handle::eof()> instead, or see L<perlfunc/eof>.
Use method C<IO::Handle::error()> instead.
Use method C<IO::Handle::flush()> instead.
See also L<perlvar/$OUTPUT_AUTOFLUSH>.
Use method C<IO::Handle::getc()> instead, or see L<perlfunc/read>.
Use method C<IO::Seekable::getpos()> instead, or see L<L/seek>.
Use method C<IO::Handle::gets()> instead. Similar to E<lt>E<gt>, also known
Use method C<IO::Handle::fileno()> instead, or see L<perlfunc/fileno>.
This is identical to the C function C<floor()>, returning the largest
integer value less than or equal to the numerical argument.
This is identical to the C function C<fmod()>.
It returns the remainder C<$r = $x - $n*$y>, where C<$n = trunc($x/$y)>.
The C<$r> has the same sign as C<$x> and magnitude (absolute value)
less than the magnitude of C<$y>.
Use method C<IO::File::open()> instead, or see L<perlfunc/open>.
This is identical to Perl's builtin C<fork()> function
for duplicating the current process, see L<perlfunc/fork>
and L<perlfork> if you are in Windows.
Retrieves the value of a configurable limit on a file or directory. This
uses file descriptors such as those obtained by calling C<POSIX::open>.
The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds C</var/foo>.
$fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
$path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );
Returns C<undef> on failure.
fprintf() is C-specific, see L<perlfunc/printf> instead.
fputc() is C-specific, see L<perlfunc/print> instead.
fputs() is C-specific, see L<perlfunc/print> instead.
fread() is C-specific, see L<perlfunc/read> instead.
free() is C-specific. Perl does memory management transparently.
freopen() is C-specific, see L<perlfunc/open> instead.
Return the mantissa and exponent of a floating-point number.
($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
fscanf() is C-specific, use E<lt>E<gt> and regular expressions instead.
Use method C<IO::Seekable::seek()> instead, or see L<perlfunc/seek>.
Use method C<IO::Seekable::setpos()> instead, or seek L<perlfunc/seek>.
Get file status. This uses file descriptors such as those obtained by
calling C<POSIX::open>. The data returned is identical to the data from
Perl's builtin C<stat> function.
$fd = POSIX::open( "foo", &POSIX::O_RDONLY );
@stats = POSIX::fstat( $fd );
Use method C<IO::Handle::sync()> instead.
Use method C<IO::Seekable::tell()> instead, or see L<perlfunc/tell>.
fwrite() is C-specific, see L<perlfunc/print> instead.
This is identical to Perl's builtin C<getc()> function,
Returns one character from STDIN. Identical to Perl's C<getc()>,
Returns the name of the current working directory.
Returns the effective group identifier. Similar to Perl' s builtin
variable C<$(>, see L<perlvar/$EGID>.
Returns the value of the specified environment variable.
The same information is available through the C<%ENV> array.
Returns the effective user identifier. Identical to Perl's builtin C<$E<gt>>
variable, see L<perlvar/$EUID>.
Returns the user's real group identifier. Similar to Perl's builtin
variable C<$)>, see L<perlvar/$GID>.
This is identical to Perl's builtin C<getgrgid()> function for
returning group entries by group identifiers, see
This is identical to Perl's builtin C<getgrnam()> function for
returning group entries by group names, see L<perlfunc/getgrnam>.
Returns the ids of the user's supplementary groups. Similar to Perl's
builtin variable C<$)>, see L<perlvar/$GID>.
This is identical to Perl's builtin C<getlogin()> function for
returning the user name associated with the current session, see
This is identical to Perl's builtin C<getpgrp()> function for
returning the process group identifier of the current process, see
Returns the process identifier. Identical to Perl's builtin
variable C<$$>, see L<perlvar/$PID>.
This is identical to Perl's builtin C<getppid()> function for
returning the process identifier of the parent process of the current
process , see L<perlfunc/getppid>.
This is identical to Perl's builtin C<getpwnam()> function for
returning user entries by user names, see L<perlfunc/getpwnam>.
This is identical to Perl's builtin C<getpwuid()> function for
returning user entries by user identifiers, see L<perlfunc/getpwuid>.
Returns one line from C<STDIN>, similar to E<lt>E<gt>, also known
as the C<readline()> function, see L<perlfunc/readline>.
B<NOTE>: if you have C programs that still use C<gets()>, be very
afraid. The C<gets()> function is a source of endless grief because
it has no buffer overrun checks. It should B<never> be used. The
C<fgets()> function should be preferred instead.
Returns the user's identifier. Identical to Perl's builtin C<$E<lt>> variable,
This is identical to Perl's builtin C<gmtime()> function for
converting seconds since the epoch to a date in Greenwich Mean Time,
This is identical to the C function, except that it can apply to a
single character or to a whole string. Note that locale settings may
affect what characters are considered C<isalnum>. Does not work on
Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:alnum:]]/> construct instead, or possibly
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<isalpha>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:alpha:]]/> construct instead.
Returns a boolean indicating whether the specified filehandle is connected
to a tty. Similar to the C<-t> operator, see L<perlfunc/-X>.
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<iscntrl>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:cntrl:]]/> construct instead.
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<isdigit> (unlikely, but
still possible). Does not work on Unicode characters code point 256
or higher. Consider using regular expressions and the C</[[:digit:]]/>
construct instead, or the C</\d/> construct.
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<isgraph>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:graph:]]/> construct instead.
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<islower>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:lower:]]/> construct instead. Do B<not> use
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<isprint>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:print:]]/> construct instead.
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<ispunct>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:punct:]]/> construct instead.
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<isspace>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:space:]]/> construct instead, or the C</\s/>
construct. (Note that C</\s/> and C</[[:space:]]/> are slightly
different in that C</[[:space:]]/> can normally match a vertical tab,
This is identical to the C function, except that it can apply to
a single character or to a whole string. Note that locale settings
may affect what characters are considered C<isupper>. Does not work
on Unicode characters code point 256 or higher. Consider using regular
expressions and the C</[[:upper:]]/> construct instead. Do B<not> use
This is identical to the C function, except that it can apply to a single
character or to a whole string. Note that locale settings may affect what
characters are considered C<isxdigit> (unlikely, but still possible).
Does not work on Unicode characters code point 256 or higher.
Consider using regular expressions and the C</[[:xdigit:]]/>
construct instead, or simply C</[0-9a-f]/i>.
This is identical to Perl's builtin C<kill()> function for sending
signals to processes (often to terminate them), see L<perlfunc/kill>.
(For returning absolute values of long integers.)
labs() is C-specific, see L<perlfunc/abs> instead.
This is identical to the C function C<ldexp()>
for multiplying floating point numbers with powers of two.
$x_quadrupled = POSIX::ldexp($x, 2);
(For computing dividends of long integers.)
ldiv() is C-specific, use C</> and C<int()> instead.
This is identical to Perl's builtin C<link()> function
for creating hard links into files, see L<perlfunc/link>.
Get numeric formatting information. Returns a reference to a hash
containing the current locale formatting values.
Here is how to query the database for the B<de> (Deutsch or German) locale.
$loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
$lconv = POSIX::localeconv();
print "decimal_point = ", $lconv->{decimal_point}, "\n";
print "thousands_sep = ", $lconv->{thousands_sep}, "\n";
print "grouping = ", $lconv->{grouping}, "\n";
print "int_curr_symbol = ", $lconv->{int_curr_symbol}, "\n";
print "currency_symbol = ", $lconv->{currency_symbol}, "\n";
print "mon_decimal_point = ", $lconv->{mon_decimal_point}, "\n";
print "mon_thousands_sep = ", $lconv->{mon_thousands_sep}, "\n";
print "mon_grouping = ", $lconv->{mon_grouping}, "\n";
print "positive_sign = ", $lconv->{positive_sign}, "\n";
print "negative_sign = ", $lconv->{negative_sign}, "\n";
print "int_frac_digits = ", $lconv->{int_frac_digits}, "\n";
print "frac_digits = ", $lconv->{frac_digits}, "\n";
print "p_cs_precedes = ", $lconv->{p_cs_precedes}, "\n";
print "p_sep_by_space = ", $lconv->{p_sep_by_space}, "\n";
print "n_cs_precedes = ", $lconv->{n_cs_precedes}, "\n";
print "n_sep_by_space = ", $lconv->{n_sep_by_space}, "\n";
print "p_sign_posn = ", $lconv->{p_sign_posn}, "\n";
print "n_sign_posn = ", $lconv->{n_sign_posn}, "\n";
This is identical to Perl's builtin C<localtime()> function for
converting seconds since the epoch to a date see L<perlfunc/localtime>.
This is identical to Perl's builtin C<log()> function,
returning the natural (I<e>-based) logarithm of the numerical argument,
This is identical to the C function C<log10()>,
returning the 10-base logarithm of the numerical argument.
sub log10 { log($_[0]) / log(10) }
sub log10 { log($_[0]) / 2.30258509299405 }
sub log10 { log($_[0]) * 0.434294481903252 }
longjmp() is C-specific: use L<perlfunc/die> instead.
Move the file's read/write position. This uses file descriptors such as
those obtained by calling C<POSIX::open>.
$fd = POSIX::open( "foo", &POSIX::O_RDONLY );
$off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );
Returns C<undef> on failure.
malloc() is C-specific. Perl does memory management transparently.
This is identical to the C function C<mblen()>.
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
This is identical to the C function C<mbstowcs()>.
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
This is identical to the C function C<mbtowc()>.
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
memchr() is C-specific, see L<perlfunc/index> instead.
memcmp() is C-specific, use C<eq> instead, see L<perlop>.
memcpy() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
memmove() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
memset() is C-specific, use C<x> instead, see L<perlop>.
This is identical to Perl's builtin C<mkdir()> function
for creating directories, see L<perlfunc/mkdir>.
This is similar to the C function C<mkfifo()> for creating
if (mkfifo($path, $mode)) { ....
Returns C<undef> on failure. The C<$mode> is similar to the
mode of C<mkdir()>, see L<perlfunc/mkdir>.
Convert date/time info to a calendar time.
mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)
The month (C<mon>), weekday (C<wday>), and yearday (C<yday>) begin at zero.
I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
year (C<year>) is given in years since 1900. I.e. The year 1995 is 95; the
year 2001 is 101. Consult your system's C<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 C<undef> on failure.
Return the integral and fractional parts of a floating-point number.
($fractional, $integral) = POSIX::modf( 3.14 );
This is similar to the C function C<nice()>, for changing
the scheduling preference of the current process. Positive
arguments mean more polite process, negative values more
needy process. Normal user processes can only be more polite.
Returns C<undef> on failure.
offsetof() is C-specific, you probably want to see L<perlfunc/pack> instead.
Open a file for reading for writing. This returns file descriptors, not
Perl filehandles. Use C<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 C<undef> on failure.
See also L<perlfunc/sysopen>.
Open a directory for reading.
$dir = POSIX::opendir( "/var" );
@files = POSIX::readdir( $dir );
Returns C<undef> on failure.
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 C</var>.
$path_max = POSIX::pathconf( "/var", &POSIX::_PC_PATH_MAX );
Returns C<undef> on failure.
This is similar to the C function C<pause()>, which suspends
the execution of the current process until a signal is received.
Returns C<undef> on failure.
This is identical to the C function C<perror()>, which outputs to the
standard error stream the specified message followed by ": " and the
current error string. Use the C<warn()> function and the C<$!>
variable instead, see L<perlfunc/warn> and L<perlvar/$ERRNO>.
Create an interprocess channel. This returns file descriptors like those
returned by C<POSIX::open>.
my ($read, $write) = POSIX::pipe();
POSIX::write( $write, "hello", 5 );
POSIX::read( $read, $buf, 5 );
See also L<perlfunc/pipe>.
Computes C<$x> raised to the power C<$exponent>.
$ret = POSIX::pow( $x, $exponent );
You can also use the C<**> operator, see L<perlop>.
Formats and prints the specified arguments to STDOUT.
See also L<perlfunc/printf>.
putc() is C-specific, see L<perlfunc/print> instead.
putchar() is C-specific, see L<perlfunc/print> instead.
puts() is C-specific, see L<perlfunc/print> instead.
qsort() is C-specific, see L<perlfunc/sort> instead.
Sends the specified signal to the current process.
See also L<perlfunc/kill> and the C<$$> in L<perlvar/$PID>.
C<rand()> is non-portable, see L<perlfunc/rand> instead.
Read from a file. This uses file descriptors such as those obtained by
calling C<POSIX::open>. If the buffer C<$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, $buf, 3 );
Returns C<undef> on failure.
See also L<perlfunc/sysread>.
This is identical to Perl's builtin C<readdir()> function
for reading directory entries, see L<perlfunc/readdir>.
realloc() is C-specific. Perl does memory management transparently.
This is identical to Perl's builtin C<unlink()> function
for removing files, see L<perlfunc/unlink>.
This is identical to Perl's builtin C<rename()> function
for renaming files, see L<perlfunc/rename>.
Seeks to the beginning of the file.
This is identical to Perl's builtin C<rewinddir()> function for
rewinding directory entry streams, see L<perlfunc/rewinddir>.
This is identical to Perl's builtin C<rmdir()> function
for removing (empty) directories, see L<perlfunc/rmdir>.
scanf() is C-specific, use E<lt>E<gt> and regular expressions instead,
Sets the real group identifier and the effective group identifier for
this process. Similar to assigning a value to the Perl's builtin
C<$)> variable, see L<perlvar/$GID>, 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
C<setjmp()> is C-specific: use C<eval {}> instead,
Modifies and queries program's locale. The following examples assume
use POSIX qw(setlocale LC_ALL LC_CTYPE);
The following will set the traditional UNIX system locale behavior
(the second argument C<"C">).
$loc = setlocale( LC_ALL, "C" );
The following will query the current LC_CTYPE category. (No second
$loc = setlocale( LC_CTYPE );
The following will set the LC_CTYPE behaviour according to the locale
environment variables (the second argument C<"">).
Please see your systems C<setlocale(3)> documentation for the locale
environment variables' meaning or consult L<perllocale>.
$loc = setlocale( LC_CTYPE, "" );
The following will set the LC_COLLATE behaviour to Argentinian
Spanish. B<NOTE>: The naming and availability of locales depends on
your operating system. Please consult L<perllocale> for how to find
out which locales are available in your system.
$loc = setlocale( LC_ALL, "es_AR.ISO8859-1" );
This is similar to the C function C<setpgid()> for
setting the process group identifier of the current process.
Returns C<undef> on failure.
This is identical to the C function C<setsid()> for
setting the session identifier of the current process.
Sets the real user identifier and the effective user identifier for
this process. Similar to assigning a value to the Perl's builtin
C<$E<lt>> variable, see L<perlvar/$UID>, except that the latter
will change only the real user identifier.
Detailed signal management. This uses C<POSIX::SigAction> objects for the
C<action> and C<oldaction> arguments. Consult your system's C<sigaction>
sigaction(signal, action, oldaction = 0)
Returns C<undef> on failure. The C<signal> must be a number (like
SIGHUP), not a string (like "SIGHUP"), though Perl does try hard
siglongjmp() is C-specific: use L<perlfunc/die> instead.
Examine signals that are blocked and pending. This uses C<POSIX::SigSet>
objects for the C<sigset> argument. Consult your system's C<sigpending>
Returns C<undef> on failure.
Change and/or examine calling process's signal mask. This uses
C<POSIX::SigSet> objects for the C<sigset> and C<oldsigset> arguments.
Consult your system's C<sigprocmask> manpage for details.
sigprocmask(how, sigset, oldsigset = 0)
Returns C<undef> on failure.
C<sigsetjmp()> is C-specific: use C<eval {}> instead,
Install a signal mask and suspend process until signal arrives. This uses
C<POSIX::SigSet> objects for the C<signal_mask> argument. Consult your
system's C<sigsuspend> manpage for details.
Returns C<undef> on failure.
This is identical to Perl's builtin C<sin()> function
for returning the sine of the numerical argument,
see L<perlfunc/sin>. See also L<Math::Trig>.
This is identical to the C function C<sinh()>
for returning the hyperbolic sine of the numerical argument.
This is functionally identical to Perl's builtin C<sleep()> function
for suspending the execution of the current for process for certain
number of seconds, see L<perlfunc/sleep>. There is one significant
difference, however: C<POSIX::sleep()> returns the number of
B<unslept> seconds, while the C<CORE::sleep()> returns the
This is similar to Perl's builtin C<sprintf()> function
for returning a string that has the arguments formatted as requested,
This is identical to Perl's builtin C<sqrt()> function.
for returning the square root of the numerical argument,
Give a seed the pseudorandom number generator, see L<perlfunc/srand>.
sscanf() is C-specific, use regular expressions instead,
This is identical to Perl's builtin C<stat()> function
for returning information about files and directories.
strcat() is C-specific, use C<.=> instead, see L<perlop>.
strchr() is C-specific, see L<perlfunc/index> instead.
strcmp() is C-specific, use C<eq> or C<cmp> instead, see L<perlop>.
This is identical to the C function C<strcoll()>
for collating (comparing) strings transformed using
the C<strxfrm()> function. Not really needed since
Perl can do this transparently, see L<perllocale>.
strcpy() is C-specific, use C<=> instead, see L<perlop>.
strcspn() is C-specific, use regular expressions instead,
Returns the error string for the specified errno.
Identical to the string form of the C<$!>, see L<perlvar/$ERRNO>.
Convert date and time information to string. Returns the string.
strftime(fmt, sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1)
The month (C<mon>), weekday (C<wday>), and yearday (C<yday>) begin at zero.
I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
year (C<year>) is given in years since 1900. I.e., the year 1995 is 95; the
year 2001 is 101. Consult your system's C<strftime()> manpage for details
about these and the other arguments.
If you want your code to be portable, your format (C<fmt>) argument
should use only the conversion specifiers defined by the ANSI C
standard (C89, to play safe). These are C<aAbBcdHIjmMpSUwWxXyYZ%>.
But even then, the B<results> of some of the conversion specifiers are
non-portable. For example, the specifiers C<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<c> changes according to the timezone settings of the
user and the timezone computation rules of the operating system.
The C<Z> specifier is notoriously unportable since the names of
timezones are non-standard. Sticking to the numeric specifiers is the
The given arguments are made consistent as though by calling
C<mktime()> before calling your system's C<strftime()> function,
except that the C<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 );
strlen() is C-specific, use C<length()> instead, see L<perlfunc/length>.
strncat() is C-specific, use C<.=> instead, see L<perlop>.
strncmp() is C-specific, use C<eq> instead, see L<perlop>.
strncpy() is C-specific, use C<=> instead, see L<perlop>.
strpbrk() is C-specific, use regular expressions instead,
strrchr() is C-specific, see L<perlfunc/rindex> instead.
strspn() is C-specific, use regular expressions instead,
This is identical to Perl's builtin C<index()> function,
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 should respect any POSIX I<setlocale()> settings.
To parse a string $str as a floating point number use
($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() is C-specific, use regular expressions instead, see
L<perlre>, or L<perlfunc/split>.
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 I<setlocale()> settings.
To parse a string $str as a number in some base $base use
($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"
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.
String to unsigned (long) integer translation. strtoul() is identical
to strtol() except that strtoul() only parses unsigned integers. See
Note: Some vendors supply strtod() and strtol() but not strtoul().
Other vendors that do supply strtoul() parse "-1" as a valid value.
String transformation. Returns the transformed string.
$dst = POSIX::strxfrm( $src );
Used in conjunction with the C<strcoll()> function, see L</strcoll>.
Not really needed since Perl can do this transparently, see
Retrieves values of system configurable variables.
The following will get the machine's clock speed.
$clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
Returns C<undef> on failure.
This is identical to Perl's builtin C<system()> function, see
This is identical to the C function C<tan()>, returning the
tangent of the numerical argument. See also L<Math::Trig>.
This is identical to the C function C<tanh()>, returning the
hyperbolic tangent of the numerical argument. See also L<Math::Trig>.
This is similar to the C function C<tcdrain()> for draining
the output queue of its argument stream.
Returns C<undef> on failure.
This is similar to the C function C<tcflow()> for controlling
the flow of its argument stream.
Returns C<undef> on failure.
This is similar to the C function C<tcflush()> for flushing
the I/O buffers of its argument stream.
Returns C<undef> on failure.
This is identical to the C function C<tcgetpgrp()> for returning the
process group identifier of the foreground process group of the controlling
This is similar to the C function C<tcsendbreak()> for sending
a break on its argument stream.
Returns C<undef> on failure.
This is similar to the C function C<tcsetpgrp()> for setting the
process group identifier of the foreground process group of the controlling
Returns C<undef> on failure.
This is identical to Perl's builtin C<time()> function
for returning the number of seconds since the epoch
(whatever it is for the system), see L<perlfunc/time>.
The times() function returns elapsed realtime since some point in the past
(such as system startup), user and system times for this process, and user
and system times used by child processes. All times are returned in clock
($realtime, $user, $system, $cuser, $csystem) = POSIX::times();
Note: Perl's builtin C<times()> function returns four values, measured in
Use method C<IO::File::new_tmpfile()> instead, or see L<File::Temp>.
Returns a name for a temporary file.
$tmpfile = POSIX::tmpnam();
For security reasons, which are probably detailed in your system's
documentation for the C library tmpnam() function, this interface
should not be used; instead see L<File::Temp>.
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using the C<lc()> function,
see L<perlfunc/lc>, or the equivalent C<\L> operator inside doublequotish
This is identical to the C function, except that it can apply to a single
character or to a whole string. Consider using the C<uc()> function,
see L<perlfunc/uc>, or the equivalent C<\U> operator inside doublequotish
This is identical to the C function C<ttyname()> for returning the
name of the current terminal.
Retrieves the time conversion information from the C<tzname> variable.
($std, $dst) = POSIX::tzname();
This is identical to the C function C<tzset()> for setting
the current timezone based on the environment variable C<TZ>,
to be used by C<ctime()>, C<localtime()>, C<mktime()>, and C<strftime()>
This is identical to Perl's builtin C<umask()> function
for setting (and querying) the file creation permission mask,
Get name of current operating system.
($sysname, $nodename, $release, $version, $machine) = POSIX::uname();
Note that the actual meanings of the various fields are not
that well standardized, do not expect any great portability.
The C<$sysname> might be the name of the operating system,
the C<$nodename> might be the name of the host, the C<$release>
might be the (major) release number of the operating system,
the C<$version> might be the (minor) release number of the
operating system, and the C<$machine> might be a hardware identifier.
Use method C<IO::Handle::ungetc()> instead.
This is identical to Perl's builtin C<unlink()> function
for removing files, see L<perlfunc/unlink>.
This is identical to Perl's builtin C<utime()> function
for changing the time stamps of files and directories,
vfprintf() is C-specific, see L<perlfunc/printf> instead.
vprintf() is C-specific, see L<perlfunc/printf> instead.
vsprintf() is C-specific, see L<perlfunc/sprintf> instead.
This is identical to Perl's builtin C<wait()> function,
Wait for a child process to change state. This is identical to Perl's
builtin C<waitpid()> function, see L<perlfunc/waitpid>.
$pid = POSIX::waitpid( -1, POSIX::WNOHANG );
print "status = ", ($? / 256), "\n";
This is identical to the C function C<wcstombs()>.
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
This is identical to the C function C<wctomb()>.
Perl does not have any support for the wide and multibyte
characters of the C standards, so this might be a rather
Write to a file. This uses file descriptors such as those obtained by
$fd = POSIX::open( "foo", &POSIX::O_WRONLY );
$bytes = POSIX::write( $b, $buf, 5 );
Returns C<undef> on failure.
See also L<perlfunc/syswrite>.
Creates a new C<POSIX::SigAction> object which corresponds to the C
C<struct sigaction>. This object will be destroyed automatically when it is
no longer needed. The first parameter is the fully-qualified name of a sub
which is a signal-handler. The second parameter is a C<POSIX::SigSet>
object, it defaults to the empty set. The third parameter contains the
C<sa_flags>, it defaults to 0.
$sigset = POSIX::SigSet->new(SIGINT, SIGQUIT);
$sigaction = POSIX::SigAction->new( \&main::handler, $sigset, &POSIX::SA_NOCLDSTOP );
This C<POSIX::SigAction> object is intended for use with the C<POSIX::sigaction()>
accessor functions to get/set the values of a SigAction object.
$sigset = $sigaction->mask;
$sigaction->flags(&POSIX::SA_RESTART);
accessor function for the "safe signals" flag of a SigAction object; see
L<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 C<POSIX::SigAction> object:
You may also examine the "safe" flag on the output action object which is
filled in when given as the third parameter to C<POSIX::sigaction()>:
sigaction(SIGINT, $new_action, $old_action);
# previous SIGINT handler used safe signals
Create a new SigSet object. This object will be destroyed automatically
when it is no longer needed. Arguments may be supplied to initialize the
$sigset = POSIX::SigSet->new;
Create a set with SIGUSR1.
$sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 );
Add a signal to a SigSet object.
$sigset->addset( &POSIX::SIGUSR2 );
Returns C<undef> on failure.
Remove a signal from the SigSet object.
$sigset->delset( &POSIX::SIGUSR2 );
Returns C<undef> on failure.
Initialize the SigSet object to be empty.
Returns C<undef> on failure.
Initialize the SigSet object to include all signals.
Returns C<undef> on failure.
Tests the SigSet object to see if it contains a specific signal.
if( $sigset->ismember( &POSIX::SIGUSR1 ) ){
print "contains SIGUSR1\n";
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;
Get terminal control attributes.
Obtain the attributes for stdin.
Obtain the attributes for stdout.
Returns C<undef> on failure.
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);
Retrieve the c_cflag field of a termios object.
$c_cflag = $termios->getcflag;
Retrieve the c_iflag field of a termios object.
$c_iflag = $termios->getiflag;
Retrieve the input baud rate.
$ispeed = $termios->getispeed;
Retrieve the c_lflag field of a termios object.
$c_lflag = $termios->getlflag;
Retrieve the c_oflag field of a termios object.
$c_oflag = $termios->getoflag;
Retrieve the output baud rate.
$ospeed = $termios->getospeed;
Set terminal control attributes.
Set attributes immediately for stdout.
$termios->setattr( 1, &POSIX::TCSANOW );
Returns C<undef> on failure.
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 );
Set the c_cflag field of a termios object.
$termios->setcflag( $c_cflag | &POSIX::CLOCAL );
Set the c_iflag field of a termios object.
$termios->setiflag( $c_iflag | &POSIX::BRKINT );
$termios->setispeed( &POSIX::B9600 );
Returns C<undef> on failure.
Set the c_lflag field of a termios object.
$termios->setlflag( $c_lflag | &POSIX::ECHO );
Set the c_oflag field of a termios object.
$termios->setoflag( $c_oflag | &POSIX::OPOST );
Set the output baud rate.
$termios->setospeed( &POSIX::B9600 );
Returns C<undef> on failure.
B38400 B75 B200 B134 B300 B1800 B150 B0 B19200 B1200 B9600 B600 B4800 B50 B2400 B110
=item Terminal interface values
TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF
VEOF VEOL VERASE VINTR VKILL VQUIT VSUSP VSTART VSTOP VMIN VTIME NCCS
=item c_cflag field values
CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD
=item c_iflag field values
BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK
=item c_lflag field values
ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP
=item c_oflag field values
=head1 PATHNAME 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_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
=head1 SYSTEM CONFIGURATION
_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
E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF
EBUSY ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ
EDOM EDQUOT EEXIST EFAULT EFBIG EHOSTDOWN EHOSTUNREACH EINPROGRESS EINTR
EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINK EMSGSIZE ENAMETOOLONG
ENETDOWN ENETRESET ENETUNREACH ENFILE ENOBUFS ENODEV ENOENT ENOEXEC
ENOLCK ENOMEM ENOPROTOOPT ENOSPC ENOSYS ENOTBLK ENOTCONN ENOTDIR
ENOTEMPTY ENOTSOCK ENOTTY ENXIO EOPNOTSUPP EPERM EPFNOSUPPORT EPIPE
EPROCLIM EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART EROFS
ESHUTDOWN ESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIMEDOUT ETOOMANYREFS
ETXTBSY EUSERS EWOULDBLOCK EXDEV
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
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
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
LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME
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
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
S_ISBLK S_ISCHR S_ISDIR S_ISFIFO S_ISREG
EXIT_FAILURE EXIT_SUCCESS MB_CUR_MAX RAND_MAX
BUFSIZ EOF FILENAME_MAX L_ctermid L_cuserid L_tmpname TMP_MAX
R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STDERR_FILENO W_OK X_OK
Do not suspend the calling process until a child process
changes state but instead return immediately.
Catch stopped child processes.
WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIFSTOPPED WSTOPSIG
WIFEXITED($?) returns true if the child process exited normally
(C<exit()> or by falling off the end of C<main()>)
WEXITSTATUS($?) returns the normal exit status of the child process
(only meaningful if WIFEXITED($?) is true)
WIFSIGNALED($?) returns true if the child process terminated because
WTERMSIG($?) returns the signal the child process terminated for
(only meaningful if WIFSIGNALED($?) is true)
WIFSTOPPED($?) returns true if the child process is currently stopped
(can happen only if you specified the WUNTRACED flag to waitpid())
WSTOPSIG($?) returns the signal the child process was stopped for
(only meaningful if WIFSTOPPED($?) is true)
projects / OpenSPARC-T2-SAM / blob