POSIX - Perl interface to IEEE Std 1003.1

- NAME
- SYNOPSIS
- DESCRIPTION
- NOTE
- CAVEATS
- FUNCTIONS
- CLASSES

- POSIX::SigAction
- 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 the perlfunc manpage 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 the Math::Trig manpage.

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`. The `$wday`, `$yday`, and `$isdst` default to zero (and the first two are usually ignored anyway).

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

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

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

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 the Math::Trig manpage.

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

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 in the perlfunc manpage.

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 in the perlfunc manpage.

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

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 in the perlfunc manpage.

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

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

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 in the perlfunc manpage.

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

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

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

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

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

  See also sysopen in the perlfunc manpage 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 in the perlfunc manpage 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 the perlvar manpage.

execl
  `execl()` is C-specific, see exec in the perlfunc manpage.

execle
  `execle()` is C-specific, see exec in the perlfunc manpage.

execlp
  `execlp()` is C-specific, see exec in the perlfunc manpage.

execv
  `execv()` is C-specific, see exec in the perlfunc manpage.

execve
  `execve()` is C-specific, see exec in the perlfunc manpage.

execvp
  `execvp()` is C-specific, see exec in the perlfunc manpage.

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

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

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

fclose
  Use method `IO::Handle::close()` instead, or see close in the perlfunc manpage.

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

fdopen
  Use method `IO::Handle::new_from_fd()` instead, or see open in the perlfunc manpage.

feof
  Use method `IO::Handle::eof()` instead, or see eof in the perlfunc manpage.

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

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

fgetc
  Use method `IO::Handle::getc()` instead, or see read in the perlfunc manpage.

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

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

fileno
  Use method `IO::Handle::fileno()` instead, or see fileno in the perlfunc manpage.

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 in the perlfunc manpage.

fork
  This is identical to Perl's builtin `fork()` function for duplicating the current process, see fork in the perlfunc manpage and the perlfork manpage 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 in the perlfunc manpage instead.

fputc
  `fputc()` is C-specific, see print in the perlfunc manpage instead.

fputs
  `fputs()` is C-specific, see print in the perlfunc manpage instead.

fread
  `fread()` is C-specific, see read in the perlfunc manpage instead.

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

freopen
  `freopen()` is C-specific, see open in the perlfunc manpage 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 in the perlfunc manpage.

fsetpos
  Use method `IO::Seekable::setpos()` instead, or seek seek in the perlfunc manpage.

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 in the perlfunc manpage.

fwrite
  `fwrite()` is C-specific, see print in the perlfunc manpage instead.

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

getchar
  Returns one character from STDIN. Identical to Perl's `getc()`, see getc in the perlfunc manpage.

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

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

getenv
  Returns the value of the specified enironment 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 the perlvar manpage.

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

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

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

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

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

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

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

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

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

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

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

  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 the perlvar manpage.

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

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 in the perlfunc manpage.

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 in the perlfunc manpage.

labs
  (For returning absolute values of long integers.) `labs()` is C-specific, see abs in the perlfunc manpage instead.

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 in the perlfunc manpage.

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 in the perlfunc manpage.

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

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 in the perlfunc manpage 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 in the perlfunc manpage instead.

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

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

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

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

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

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

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

  Returns `undef` on failure. The `$mode` is similar to the mode of `mkdir()`, see mkdir in the perlfunc manpage.

mktime
  Convert date/time info to a calendar time.

  Synopsis:

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

  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 in the perlfunc manpage instead.

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

  Open a file read-only with mode 0666.

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

  Open a file for read and write.

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

  Open a file for write, with truncation.

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

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

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

  Returns `undef` on failure.

  See also sysopen in the perlfunc manpage.

opendir
  Open a directory for reading.

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

  Returns `undef` on failure.

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

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

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

  Returns `undef` on failure.

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

  Returns `undef` on failure.

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

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

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

  See also pipe in the perlfunc manpage.

pow
  Computes `$x` raised to the power `$exponent`.

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

  You can also use the `**` operator, see the perlop manpage.

printf
  Formats and prints the specified arguments to STDOUT. See also printf in the perlfunc manpage.

putc
  `putc()` is C-specific, see print in the perlfunc manpage instead.

putchar
  `putchar()` is C-specific, see print in the perlfunc manpage instead.

puts
  `puts()` is C-specific, see print in the perlfunc manpage instead.

qsort
  `qsort()` is C-specific, see sort in the perlfunc manpage instead.

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

rand
  `rand()` is non-portable, see rand in the perlfunc manpage instead.

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

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

  Returns `undef` on failure.

  See also sysread in the perlfunc manpage.

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

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 in the perlfunc manpage.

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

rewind
  Seeks to the beginning of the file.

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

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

scanf
  `scanf()` is C-specific, use <> and regular expressions instead, see the perlre manpage.

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 $GID in the perlvar manpage, 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 in the perlfunc manpage.

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 the perllocale manpage.

              $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 the perllocale manpage for how to find out which locales are available in your system.

              $loc = setlocale( LC_ALL, "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 the perlvar manpage, 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. Consult your system's `sigaction` manpage for details.

  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.

siglongjmp
  `siglongjmp()` is C-specific: use die in the perlfunc manpage 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 in the perlfunc manpage.

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

  Synopsis:

              sigsuspend(signal_mask)

  Returns `undef` on failure.

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

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

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

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

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

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

sscanf
  `sscanf()` is C-specific, use regular expressions instead, see the perlre manpage.

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

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

strchr
  `strchr()` is C-specific, see index in the perlfunc manpage instead.

strcmp
  `strcmp()` is C-specific, use `eq` or `cmp` instead, see the perlop manpage.

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 the perllocale manpage.

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

strcspn
  `strcspn()` is C-specific, use regular expressions instead, see the perlre manpage.

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

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 in the perlfunc manpage.

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

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

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

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

strrchr
  `strrchr()` is C-specific, see rindex in the perlfunc manpage instead.

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

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

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 the perlre manpage, or split in the perlfunc manpage.

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 the perllocale manpage.

sysconf
  Retrieves values of system configurable variables.

  The following will get the machine's clock speed.

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

  Returns `undef` on failure.

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

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

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

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 in the perlfunc manpage.

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 the File::Temp manpage.

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 the File::Temp manpage.

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 in the perlfunc manpage, 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 in the perlfunc manpage, 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 in the perlfunc manpage.

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 in the perlfunc manpage.

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

vfprintf
  `vfprintf()` is C-specific, see printf in the perlfunc manpage instead.

vprintf
  `vprintf()` is C-specific, see printf in the perlfunc manpage instead.

vsprintf
  `vsprintf()` is C-specific, see sprintf in the perlfunc manpage instead.

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

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

              $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
              print "status = ", ($? / 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( $b, $buf, 5 );

  Returns `undef` on failure.

  See also syswrite in the perlfunc manpage.

# 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 fully-qualified name of a sub which is a signal-handler. 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( \&main::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 the perlipc manpage 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::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()

  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)

POSIX - Perl interface to IEEE Std 1003.1