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=head1 NAME

POSIX - Perl interface to IEEE Std 1003.1

=head1 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

=head1 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.  Things which are C<#defines> in C, like EINTR or O_NDELAY, are
automatically exported into your namespace.  All functions are only exported
if you ask for them explicitly.  Most likely people will prefer to use the
fully-qualified function names.

This document gives a condensed list of the features available in the POSIX
module.  Consult your operating system's manpages for general information on
most features.  Consult L<perlfunc> for functions which are noted as being
identical to Perl's builtin functions.

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

=head1 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.

=head1 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.

=head1 FUNCTIONS

=over 8

=item _exit

This is identical to the C function C<_exit()>.

=item abort

This is identical to the C function C<abort()>.

=item abs

This is identical to Perl's builtin C<abs()> function.

=item access

Determines the accessibility of a file.

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

Returns C<undef> on failure.

=item acos

This is identical to the C function C<acos()>.

=item alarm

This is identical to Perl's builtin C<alarm()> function.

=item asctime

This is identical to the C function C<asctime()>.

=item asin

This is identical to the C function C<asin()>.

=item assert

Unimplemented.

=item atan

This is identical to the C function C<atan()>.

=item atan2

This is identical to Perl's builtin C<atan2()> function.

=item atexit

atexit() is C-specific: use END {} instead.

=item atof

atof() is C-specific.

=item atoi

atoi() is C-specific.

=item atol

atol() is C-specific.

=item bsearch

bsearch() not supplied.

=item calloc

calloc() is C-specific.

=item ceil

This is identical to the C function C<ceil()>.

=item chdir

This is identical to Perl's builtin C<chdir()> function.

=item chmod

This is identical to Perl's builtin C<chmod()> function.

=item chown

This is identical to Perl's builtin C<chown()> function.

=item clearerr

Use method C<IO::Handle::clearerr()> instead.

=item clock

This is identical to the C function C<clock()>.

=item close

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

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

Returns C<undef> on failure.

=item closedir

This is identical to Perl's builtin C<closedir()> function.

=item cos

This is identical to Perl's builtin C<cos()> function.

=item cosh

This is identical to the C function C<cosh()>.

=item creat

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

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

=item ctermid

Generates the path name for the controlling terminal.

    $path = POSIX::ctermid();

=item ctime

This is identical to the C function C<ctime()>.

=item cuserid

Get the character login name of the user.

    $name = POSIX::cuserid();

=item difftime

This is identical to the C function C<difftime()>.

=item div

div() is C-specific.

=item dup

This is similar to the C function C<dup()>.

This uses file descriptors such as those obtained by calling
C<POSIX::open>.

Returns C<undef> on failure.

=item dup2

This is similar to the C function C<dup2()>.

This uses file descriptors such as those obtained by calling
C<POSIX::open>.

Returns C<undef> on failure.

=item errno

Returns the value of errno.

    $errno = POSIX::errno();

=item execl

execl() is C-specific.

=item execle

execle() is C-specific.

=item execlp

execlp() is C-specific.

=item execv

execv() is C-specific.

=item execve

execve() is C-specific.

=item execvp

execvp() is C-specific.

=item exit

This is identical to Perl's builtin C<exit()> function.

=item exp

This is identical to Perl's builtin C<exp()> function.

=item fabs

This is identical to Perl's builtin C<abs()> function.

=item fclose

Use method C<IO::Handle::close()> instead.

=item fcntl

This is identical to Perl's builtin C<fcntl()> function.

=item fdopen

Use method C<IO::Handle::new_from_fd()> instead.

=item feof

Use method C<IO::Handle::eof()> instead.

=item ferror

Use method C<IO::Handle::error()> instead.

=item fflush

Use method C<IO::Handle::flush()> instead.

=item fgetc

Use method C<IO::Handle::getc()> instead.

=item fgetpos

Use method C<IO::Seekable::getpos()> instead.

=item fgets

Use method C<IO::Handle::gets()> instead.

=item fileno

Use method C<IO::Handle::fileno()> instead.

=item floor

This is identical to the C function C<floor()>.

=item fmod

This is identical to the C function C<fmod()>.

=item fopen

Use method C<IO::File::open()> instead.

=item fork

This is identical to Perl's builtin C<fork()> function.

=item fpathconf

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

The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds C</tmp/foo>.

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

Returns C<undef> on failure.

=item fprintf

fprintf() is C-specific--use printf instead.

=item fputc

fputc() is C-specific--use print instead.

=item fputs

fputs() is C-specific--use print instead.

=item fread

fread() is C-specific--use read instead.

=item free

free() is C-specific.

=item freopen

freopen() is C-specific--use open instead.

=item frexp

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

    ($mantissa, $exponent) = POSIX::frexp( 3.14 );

=item fscanf

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

=item fseek

Use method C<IO::Seekable::seek()> instead.

=item fsetpos

Use method C<IO::Seekable::setpos()> instead.

=item fstat

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

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

=item ftell

Use method C<IO::Seekable::tell()> instead.

=item fwrite

fwrite() is C-specific--use print instead.

=item getc

This is identical to Perl's builtin C<getc()> function.

=item getchar

Returns one character from STDIN.

=item getcwd

Returns the name of the current working directory.

=item getegid

Returns the effective group id.

=item getenv

Returns the value of the specified enironment variable.

=item geteuid

Returns the effective user id.

=item getgid

Returns the user's real group id.

=item getgrgid

This is identical to Perl's builtin C<getgrgid()> function.

=item getgrnam

This is identical to Perl's builtin C<getgrnam()> function.

=item getgroups

Returns the ids of the user's supplementary groups.

=item getlogin

This is identical to Perl's builtin C<getlogin()> function.

=item getpgrp

This is identical to Perl's builtin C<getpgrp()> function.

=item getpid

Returns the process's id.

=item getppid

This is identical to Perl's builtin C<getppid()> function.

=item getpwnam

This is identical to Perl's builtin C<getpwnam()> function.

=item getpwuid

This is identical to Perl's builtin C<getpwuid()> function.

=item gets

Returns one line from STDIN.

=item getuid

Returns the user's id.

=item gmtime

This is identical to Perl's builtin C<gmtime()> function.

=item isalnum

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isalpha

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isatty

Returns a boolean indicating whether the specified filehandle is connected
to a tty.

=item iscntrl

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isdigit

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isgraph

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item islower

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isprint

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item ispunct

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isspace

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isupper

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item isxdigit

This is identical to the C function, except that it can apply to a single
character or to a whole string.

=item kill

This is identical to Perl's builtin C<kill()> function.

=item labs

labs() is C-specific, use abs instead.

=item ldexp

This is identical to the C function C<ldexp()>.

=item ldiv

ldiv() is C-specific, use / and int instead.

=item link

This is identical to Perl's builtin C<link()> function.

=item localeconv

Get numeric formatting information.  Returns a reference to a hash
containing the current locale formatting values.

The database for the B<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";

=item localtime

This is identical to Perl's builtin C<localtime()> function.

=item log

This is identical to Perl's builtin C<log()> function.

=item log10

This is identical to the C function C<log10()>.

=item longjmp

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

=item lseek

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

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

Returns C<undef> on failure.

=item malloc

malloc() is C-specific.

=item mblen

This is identical to the C function C<mblen()>.

=item mbstowcs

This is identical to the C function C<mbstowcs()>.

=item mbtowc

This is identical to the C function C<mbtowc()>.

=item memchr

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

=item memcmp

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

=item memcpy

memcpy() is C-specific, use = instead.

=item memmove

memmove() is C-specific, use = instead.

=item memset

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

=item mkdir

This is identical to Perl's builtin C<mkdir()> function.

=item mkfifo

This is similar to the C function C<mkfifo()>.

Returns C<undef> on failure.

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

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

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

Returns C<undef> on failure.

=item modf

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

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

=item nice

This is similar to the C function C<nice()>.

Returns C<undef> on failure.

=item offsetof

offsetof() is C-specific.

=item open

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

Open a file read-only with mode 0666.

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

Open a file for read and write.

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

Open a file for write, with truncation.

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

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

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

Returns C<undef> on failure.

=item opendir

Open a directory for reading.

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

Returns C<undef> on failure.

=item 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 C</tmp>.

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

Returns C<undef> on failure.

=item pause

This is similar to the C function C<pause()>.

Returns C<undef> on failure.

=item perror

This is identical to the C function C<perror()>.

=item pipe

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

    ($fd0, $fd1) = POSIX::pipe();
    POSIX::write( $fd0, "hello", 5 );
    POSIX::read( $fd1, $buf, 5 );

=item pow

Computes $x raised to the power $exponent.

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

=item printf

Prints the specified arguments to STDOUT.

=item putc

putc() is C-specific--use print instead.

=item putchar

putchar() is C-specific--use print instead.

=item puts

puts() is C-specific--use print instead.

=item qsort

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

=item raise

Sends the specified signal to the current process.

=item rand

rand() is non-portable, use Perl's rand instead.

=item read

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

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

Returns C<undef> on failure.

=item readdir

This is identical to Perl's builtin C<readdir()> function.

=item realloc

realloc() is C-specific.

=item remove

This is identical to Perl's builtin C<unlink()> function.

=item rename

This is identical to Perl's builtin C<rename()> function.

=item rewind

Seeks to the beginning of the file.

=item rewinddir

This is identical to Perl's builtin C<rewinddir()> function.

=item rmdir

This is identical to Perl's builtin C<rmdir()> function.

=item scanf

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

=item setgid

Sets the real group id for this process.

=item setjmp

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

=item 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<"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 C<"">).
Please see your systems L<setlocale(3)> documentation for the locale
environment variables' meaning or consult L<perllocale>.

    $loc = setlocale( LC_CTYPE, "" );

The following will set the LC_COLLATE behaviour to Argentinian
Spanish. B<NOTE>: The naming and availability of locales depends on
your operating system. Please consult L<perllocale> for how to find
out which locales are available in your system.

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

=item setpgid

This is similar to the C function C<setpgid()>.

Returns C<undef> on failure.

=item setsid

This is identical to the C function C<setsid()>.

=item setuid

Sets the real user id for this process.

=item sigaction

Detailed signal management.  This uses C<POSIX::SigAction> objects for the
C<action> and C<oldaction> arguments.  Consult your system's C<sigaction>
manpage for details.

Synopsis:

    sigaction(sig, action, oldaction = 0)

Returns C<undef> on failure.

=item siglongjmp

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

=item sigpending

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

Synopsis:

    sigpending(sigset)

Returns C<undef> on failure.

=item sigprocmask

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

Synopsis:

    sigprocmask(how, sigset, oldsigset = 0)

Returns C<undef> on failure.

=item sigsetjmp

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

=item sigsuspend

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

Synopsis:

    sigsuspend(signal_mask)

Returns C<undef> on failure.

=item sin

This is identical to Perl's builtin C<sin()> function.

=item sinh

This is identical to the C function C<sinh()>.

=item sleep

This is identical to Perl's builtin C<sleep()> function.

=item sprintf

This is identical to Perl's builtin C<sprintf()> function.

=item sqrt

This is identical to Perl's builtin C<sqrt()> function.

=item srand

srand().

=item sscanf

sscanf() is C-specific--use regular expressions instead.

=item stat

This is identical to Perl's builtin C<stat()> function.

=item strcat

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

=item strchr

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

=item strcmp

strcmp() is C-specific, use eq instead.

=item strcoll

This is identical to the C function C<strcoll()>.

=item strcpy

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

=item strcspn

strcspn() is C-specific, use regular expressions instead.

=item strerror

Returns the error string for the specified errno.

=item 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 (C<mon>), weekday (C<wday>), and yearday (C<yday>) begin at zero.
I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1.  The
year (C<year>) is given in years since 1900.  I.e., the year 1995 is 95; the
year 2001 is 101.  Consult your system's C<strftime()> manpage for details
about these and the other arguments.
If you want your code to be portable, your format (C<fmt>) argument
should use only the conversion specifiers defined by the ANSI C
standard.  These are C<aAbBcdHIjmMpSUwWxXyYZ%>.
The given arguments are made consistent
as though by calling C<mktime()> before calling your system's
C<strftime()> function, except that the C<isdst> value is not affected.

The string for Tuesday, December 12, 1995.

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

=item strlen

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

=item strncat

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

=item strncmp

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

=item strncpy

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

=item stroul

stroul() is C-specific.

=item strpbrk

strpbrk() is C-specific.

=item strrchr

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

=item strspn

strspn() is C-specific.

=item strstr

This is identical to Perl's builtin C<index()> function.

=item 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 I<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.

=item strtok

strtok() is C-specific.

=item 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 I<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.

=item strtoul

String to unsigned (long) integer translation.  strtoul is identical
to strtol except that strtoul only parses unsigned integers.  See
I<strtol> for details.

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

=item strxfrm

String transformation.  Returns the transformed string.

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

=item 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 C<undef> on failure.

=item system

This is identical to Perl's builtin C<system()> function.

=item tan

This is identical to the C function C<tan()>.

=item tanh

This is identical to the C function C<tanh()>.

=item tcdrain

This is similar to the C function C<tcdrain()>.

Returns C<undef> on failure.

=item tcflow

This is similar to the C function C<tcflow()>.

Returns C<undef> on failure.

=item tcflush

This is similar to the C function C<tcflush()>.

Returns C<undef> on failure.

=item tcgetpgrp

This is identical to the C function C<tcgetpgrp()>.

=item tcsendbreak

This is similar to the C function C<tcsendbreak()>.

Returns C<undef> on failure.

=item tcsetpgrp

This is similar to the C function C<tcsetpgrp()>.

Returns C<undef> on failure.

=item time

This is identical to Perl's builtin C<time()> function.

=item 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 C<times()> function returns four values, measured in
seconds.

=item tmpfile

Use method C<IO::File::new_tmpfile()> instead.

=item tmpnam

Returns a name for a temporary file.

    $tmpfile = POSIX::tmpnam();

=item tolower

This is identical to Perl's builtin C<lc()> function.

=item toupper

This is identical to Perl's builtin C<uc()> function.

=item ttyname

This is identical to the C function C<ttyname()>.

=item tzname

Retrieves the time conversion information from the C<tzname> variable.

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

=item tzset

This is identical to the C function C<tzset()>.

=item umask

This is identical to Perl's builtin C<umask()> function.

=item uname

Get name of current operating system.

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

=item ungetc

Use method C<IO::Handle::ungetc()> instead.

=item unlink

This is identical to Perl's builtin C<unlink()> function.

=item utime

This is identical to Perl's builtin C<utime()> function.

=item vfprintf

vfprintf() is C-specific.

=item vprintf

vprintf() is C-specific.

=item vsprintf

vsprintf() is C-specific.

=item wait

This is identical to Perl's builtin C<wait()> function.

=item waitpid

Wait for a child process to change state.  This is identical to Perl's
builtin C<waitpid()> function.

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

=item wcstombs

This is identical to the C function C<wcstombs()>.

=item wctomb

This is identical to the C function C<wctomb()>.

=item write

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

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

Returns C<undef> on failure.

=back

=head1 CLASSES

=head2 POSIX::SigAction

=over 8

=item new

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

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

This C<POSIX::SigAction> object should be used with the C<POSIX::sigaction()>
function.

=back

=head2 POSIX::SigSet

=over 8

=item 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 );

=item addset

Add a signal to a SigSet object.

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

Returns C<undef> on failure.

=item delset

Remove a signal from the SigSet object.

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

Returns C<undef> on failure.

=item emptyset

Initialize the SigSet object to be empty.

    $sigset->emptyset();

Returns C<undef> on failure.

=item fillset

Initialize the SigSet object to include all signals.

    $sigset->fillset();

Returns C<undef> on failure.

=item ismember

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

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

=back

=head2 POSIX::Termios

=over 8

=item 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;

=item getattr

Get terminal control attributes.

Obtain the attributes for stdin.

    $termios->getattr()

Obtain the attributes for stdout.

    $termios->getattr( 1 )

Returns C<undef> on failure.

=item 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);

=item getcflag

Retrieve the c_cflag field of a termios object.

    $c_cflag = $termios->getcflag;

=item getiflag

Retrieve the c_iflag field of a termios object.

    $c_iflag = $termios->getiflag;

=item getispeed

Retrieve the input baud rate.

    $ispeed = $termios->getispeed;

=item getlflag

Retrieve the c_lflag field of a termios object.

    $c_lflag = $termios->getlflag;

=item getoflag

Retrieve the c_oflag field of a termios object.

    $c_oflag = $termios->getoflag;

=item getospeed

Retrieve the output baud rate.

    $ospeed = $termios->getospeed;

=item setattr

Set terminal control attributes.

Set attributes immediately for stdout.

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

Returns C<undef> on failure.

=item 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 );

=item setcflag

Set the c_cflag field of a termios object.

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

=item setiflag

Set the c_iflag field of a termios object.

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

=item setispeed

Set the input baud rate.

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

Returns C<undef> on failure.

=item setlflag

Set the c_lflag field of a termios object.

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

=item setoflag

Set the c_oflag field of a termios object.

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

=item setospeed

Set the output baud rate.

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

Returns C<undef> on failure.

=item Baud rate values

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

=item Terminal interface values

TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF

=item c_cc field values

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

=item c_cflag field values

CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD

=item c_iflag field values

BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK

=item c_lflag field values

ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP

=item c_oflag field values

OPOST

=back

=head1 PATHNAME CONSTANTS

=over 8

=item 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

=back

=head1 POSIX CONSTANTS

=over 8

=item 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

=back

=head1 SYSTEM CONFIGURATION

=over 8

=item Constants

_SC_ARG_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_JOB_CONTROL _SC_NGROUPS_MAX _SC_OPEN_MAX _SC_SAVED_IDS _SC_STREAM_MAX _SC_TZNAME_MAX _SC_VERSION

=back

=head1 ERRNO

=over 8

=item 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

=back

=head1 FCNTL

=over 8

=item 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

=back

=head1 FLOAT

=over 8

=item 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

=back

=head1 LIMITS

=over 8

=item 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

=back

=head1 LOCALE

=over 8

=item Constants

LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME

=back

=head1 MATH

=over 8

=item Constants

HUGE_VAL

=back

=head1 SIGNAL

=over 8

=item 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

=back

=head1 STAT

=over 8

=item 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

=item Macros

S_ISBLK S_ISCHR S_ISDIR S_ISFIFO S_ISREG

=back

=head1 STDLIB

=over 8

=item Constants

EXIT_FAILURE EXIT_SUCCESS MB_CUR_MAX RAND_MAX

=back

=head1 STDIO

=over 8

=item Constants

BUFSIZ EOF FILENAME_MAX L_ctermid L_cuserid L_tmpname TMP_MAX

=back

=head1 TIME

=over 8

=item Constants

CLK_TCK CLOCKS_PER_SEC

=back

=head1 UNISTD

=over 8

=item Constants

R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STRERR_FILENO W_OK X_OK

=back

=head1 WAIT

=over 8

=item Constants

WNOHANG WUNTRACED

=item Macros

WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIFSTOPPED WSTOPSIG

=back

=head1 CREATION

This document generated by ./mkposixman.PL version 19960129.