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# POSIX

Perl 5 version 12.2 documentation
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# POSIX

- NAME
- SYNOPSIS
- DESCRIPTION
- NOTE
- CAVEATS
- FUNCTIONS
- CLASSES
  - POSIX::SigAction
  - POSIX::SigRt
  - POSIX::SigSet
  - POSIX::Termios
- PATHNAME CONSTANTS
- POSIX CONSTANTS
- SYSTEM CONFIGURATION
- ERRNO
- FCNTL
- FLOAT
- LIMITS
- LOCALE
- MATH
- SIGNAL
- STAT
- STDLIB
- STDIO
- TIME
- UNISTD
- WAIT

# 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 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 interfaces.

Everything is exported by default with the exception of any POSIX functions with the same name as a built-in Perl function, such as `abs`, `alarm`, `rmdir`, `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 `use POSIX ()` and then use the fully qualified names (ie. `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 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 1003.1b-1993.

# NOTE

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 source of wisdom.

# CAVEATS

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.

# 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.

- 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.

- assert

  Unimplemented, but you can use die 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.

- 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

  atexit() is C-specific: use `END {}` instead, see perlsub.

- atof

  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

  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.

- atol

  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.

- bsearch

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

- calloc

  calloc() is C-specific. Perl does memory management transparently.

- 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.

- chmod

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

- chown

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

- clearerr

  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.

- closedir

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

- cos

  This is identical to Perl's builtin `cos()` function, for returning the cosine of its numerical argument, see cos. 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.

- 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 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

  div() is C-specific, use int 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.

- errno

  Returns the value of errno.

      	$errno = POSIX::errno();

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

- execl

  execl() is C-specific, see exec.

- execle

  execle() is C-specific, see exec.

- execlp

  execlp() is C-specific, see exec.

- execv

  execv() is C-specific, see exec.

- execve

  execve() is C-specific, see exec.

- execvp

  execvp() is C-specific, see exec.

- exit

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

- exp

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

- fabs

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

- fclose

  Use method `IO::Handle::close()` instead, or see close.

- fcntl

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

- fdopen

  Use method `IO::Handle::new_from_fd()` instead, or see open.

- feof

  Use method `IO::Handle::eof()` instead, or see eof.

- ferror

  Use method `IO::Handle::error()` instead.

- fflush

  Use method `IO::Handle::flush()` instead. See also $OUTPUT_AUTOFLUSH in perlvar.

- fgetc

  Use method `IO::Handle::getc()` instead, or see read.

- fgetpos

  Use method `IO::Seekable::getpos()` instead, or see seek in L.

- fgets

  Use method `IO::Handle::gets()` instead. Similar to <>, also known as readline.

- fileno

  Use method `IO::Handle::fileno()` instead, or see fileno.

- floor

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

- 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

  Use method `IO::File::open()` instead, or see open.

- fork

  This is identical to Perl's builtin `fork()` function for duplicating the current process, see fork 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.

- fprintf

  fprintf() is C-specific, see printf instead.

- fputc

  fputc() is C-specific, see print instead.

- fputs

  fputs() is C-specific, see print instead.

- fread

  fread() is C-specific, see read instead.

- free

  free() is C-specific. Perl does memory management transparently.

- freopen

  freopen() is C-specific, see open instead.

- frexp

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

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

- fscanf

  fscanf() is C-specific, use <> and regular expressions instead.

- fseek

  Use method `IO::Seekable::seek()` instead, or see seek.

- fsetpos

  Use method `IO::Seekable::setpos()` instead, or seek seek.

- 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

  Use method `IO::Handle::sync()` instead.

- ftell

  Use method `IO::Seekable::tell()` instead, or see tell.

- fwrite

  fwrite() is C-specific, see print instead.

- getc

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

- getchar

  Returns one character from STDIN. Identical to Perl's `getc()`, see getc.

- 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.

- getgrnam

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

- 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.

- getpgrp

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

- 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.

- getpwnam

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

- getpwuid

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

- gets

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

  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.

- isalnum

  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 `isalnum` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:alnum:]]/` construct instead, or possibly the `/\w/` construct.

- isalpha

  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 `isalpha` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:alpha:]]/` construct instead.

- isatty

  Returns a boolean indicating whether the specified filehandle is connected to a tty. Similar to the `-t` operator, see -X.

- iscntrl

  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 `iscntrl` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:cntrl:]]/` construct instead.

- isdigit

  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 `isdigit` (unlikely, but still possible). Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:digit:]]/` construct instead, or the `/\d/` construct.

- isgraph

  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 `isgraph` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:graph:]]/` construct instead.

- islower

  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 `islower` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:lower:]]/` construct instead. Do not use `/[a-z]/` .

- isprint

  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 `isprint` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:print:]]/` construct instead.

- ispunct

  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 `ispunct` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:punct:]]/` construct instead.

- isspace

  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 `isspace` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:space:]]/` construct instead, or the `/\s/` construct. (Note that `/\s/` and `/[[:space:]]/` are slightly different in that `/[[:space:]]/` can normally match a vertical tab, while `/\s/` does not.)

- isupper

  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 `isupper` . Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:upper:]]/` construct instead. Do not use `/[A-Z]/` .

- isxdigit

  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 `isxdigit` (unlikely, but still possible). Does not work on Unicode characters code point 256 or higher. Consider using regular expressions and the `/[[:xdigit:]]/` construct instead, or simply `/[0-9a-f]/i` .

- kill

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

- labs

  (For returning absolute values of long integers.) labs() is C-specific, see abs 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 an 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.

- 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

  (For computing dividends of long integers.) ldiv() is C-specific, use `/` and `int()` instead.

- link

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

- localeconv

  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 de (Deutsch or German) locale.

      	$loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );	print "Locale = $loc\n";	$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";

- localtime

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

- log

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

- 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

  longjmp() is C-specific: use die 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.

- malloc

  malloc() is C-specific. Perl does memory management transparently.

- mblen

  This is identical to the C function `mblen()` . Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function.

- mbstowcs

  This is identical to the C function `mbstowcs()` . Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function.

- mbtowc

  This is identical to the C function `mbtowc()` . Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function.

- memchr

  memchr() is C-specific, see index instead.

- memcmp

  memcmp() is C-specific, use `eq` instead, see perlop.

- memcpy

  memcpy() is C-specific, use `=` , see perlop, or see substr.

- memmove

  memmove() is C-specific, use `=` , see perlop, or see substr.

- memset

  memset() is C-specific, use `x` instead, see perlop.

- mkdir

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

- mkfifo

  This is similar to the C function `mkfifo()` for creating FIFO special files.

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

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

- nice

  This is similar to the C function `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 `undef` on failure.

- offsetof

  offsetof() is C-specific, you probably want to see pack 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.

- 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 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.

- 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.

- putc

  putc() is C-specific, see print instead.

- putchar

  putchar() is C-specific, see print instead.

- puts

  puts() is C-specific, see print instead.

- qsort

  qsort() is C-specific, see sort instead.

- raise

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

- rand

  `rand()` is non-portable, see rand 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.

- readdir

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

- realloc

  realloc() is C-specific. Perl does memory management transparently.

- remove

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

- rename

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

- 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.

- rmdir

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

- scanf

  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

  `setjmp()` is C-specific: use `eval {}` instead, see eval.

- setlocale

  Modifies and queries program's locale. 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 systems `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

  siglongjmp() is C-specific: use die instead.

- 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.

- sigsetjmp

  `sigsetjmp()` is C-specific: use `eval {}` instead, see eval.

- 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. 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. 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.

- sqrt

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

- srand

  Give a seed the pseudorandom number generator, see srand.

- sscanf

  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

  strcat() is C-specific, use `.=` instead, see perlop.

- strchr

  strchr() is C-specific, see index instead.

- strcmp

  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

  strcpy() is C-specific, use `=` instead, see perlop.

- strcspn

  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 the `$!` , 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

  strlen() is C-specific, use `length()` instead, see length.

- strncat

  strncat() is C-specific, use `.=` instead, see perlop.

- strncmp

  strncmp() is C-specific, use `eq` instead, see perlop.

- strncpy

  strncpy() is C-specific, use `=` instead, see perlop.

- strpbrk

  strpbrk() is C-specific, use regular expressions instead, see perlre.

- strrchr

  strrchr() is C-specific, see rindex instead.

- strspn

  strspn() is C-specific, use regular expressions instead, see perlre.

- strstr

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

- 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 should respect any POSIX setlocale() settings.

  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

  strtok() is C-specific, use regular expressions instead, see perlre, or split.

- 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.

- 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.

- 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.

- 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.

- 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

  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. Consider using the `lc()` function, see lc, or the equivalent `\L` operator inside doublequotish strings.

- toupper

  This is identical to the C function, except that it can apply to a single character or to a whole string. Consider using the `uc()` function, see uc, or the equivalent `\U` operator inside doublequotish strings.

- 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.

- 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

  Use method `IO::Handle::ungetc()` instead.

- unlink

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

- utime

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

- vfprintf

  vfprintf() is C-specific, see printf instead.

- vprintf

  vprintf() is C-specific, see printf instead.

- vsprintf

  vsprintf() is C-specific, see sprintf instead.

- wait

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

- waitpid

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

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

- wcstombs

  This is identical to the C function `wcstombs()` . Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function.

- wctomb

  This is identical to the C function `wctomb()` . Perl does not have any support for the wide and multibyte characters of the C standards, so this might be a rather useless function.

- 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.

# 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 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

# 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

# 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

# MATH

- Constants

  HUGE_VAL

# 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($?) returns true if the child process exited normally (`exit()` or by falling off the end of `main()` )

  - WEXITSTATUS

    WEXITSTATUS($?) returns the normal exit status of the child process (only meaningful if WIFEXITED($?) is true)

  - WIFSIGNALED

    WIFSIGNALED($?) returns true if the child process terminated because of a signal

  - WTERMSIG

    WTERMSIG($?) returns the signal the child process terminated for (only meaningful if WIFSIGNALED($?) is true)

  - WIFSTOPPED

    WIFSTOPPED($?) returns true if the child process is currently stopped (can happen only if you specified the WUNTRACED flag to waitpid())

  - WSTOPSIG

    WSTOPSIG($?) returns the signal the child process was stopped for (only meaningful if WIFSTOPPED($?) is true)

Page index

- NAME
- SYNOPSIS
- DESCRIPTION
- NOTE
- CAVEATS
- FUNCTIONS
- CLASSES
  - POSIX::SigAction
  - POSIX::SigRt
  - POSIX::SigSet
  - POSIX::Termios
- PATHNAME CONSTANTS
- POSIX CONSTANTS
- SYSTEM CONFIGURATION
- ERRNO
- FCNTL
- FLOAT
- LIMITS
- LOCALE
- MATH
- SIGNAL
- STAT
- STDLIB
- STDIO
- TIME
- UNISTD
- WAIT