POSIX






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POSIX

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.

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

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

CAVEATS

Everything is exported by default (with a handful of exceptions). This is an unfortunate backwards compatibility feature and its use is strongly discouraged. You should either prevent the exporting (by saying use POSIX ();, as usual) and then use fully qualified names (e.g. POSIX::SEEK_END), or give an explicit import list. If you do neither and opt for the default (as in use POSIX;), you will import hundreds and hundreds of symbols into your namespace.

A few functions are not implemented because they are C specific. If you attempt to call these, they will print a message telling you that they aren't implemented, and suggest using the Perl equivalent, should one exist. For example, trying to access the setjmp() call will elicit the message "setjmp() is C-specific: use eval {} instead".

Furthermore, some evil vendors will claim 1003.1 compliance, but in fact are not so: they will not pass the PCTS (POSIX Compliance Test Suites). For example, one vendor may not define EDEADLK, or the semantics of the errno values set by open(2) might not be quite right. Perl does not attempt to verify POSIX compliance. That means you can currently successfully say "use POSIX", and then later in your program you find that your vendor has been lax and there's no usable ICANON macro after all. This could be construed to be a bug.

FUNCTIONS

_exit

This is identical to the C function _exit(). It exits the program immediately which means among other things buffered I/O is not flushed.

Note that when using threads and in Linux this is not a good way to exit a thread because in Linux processes and threads are kind of the same thing (Note: while this is the situation in early 2003 there are projects under way to have threads with more POSIXly semantics in Linux). If you want not to return from a thread, detach the thread.

abort
This is identical to the C function abort(). It terminates the process with a SIGABRT signal unless caught by a signal handler or if the handler does not return normally (it e.g. does a longjmp).
abs
This is identical to Perl's builtin abs() function, returning the absolute value of its numerical argument.
access

Determines the accessibility of a file.

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

Returns undef on failure. Note: do not use access() for security purposes. Between the access() call and the operation you are preparing for the permissions might change: a classic race condition.

acos
This is identical to the C function acos(), returning the arcus cosine of its numerical argument. See also Math::Trig.
acosh
This is identical to the C function acosh(), returning the hyperbolic arcus cosine of its numerical argument [C99]. See also Math::Trig.
alarm
This is identical to Perl's builtin alarm() function, either for arming or disarming the SIGARLM timer.
asctime

This is identical to the C function asctime(). It returns a string of the form

	"Fri Jun  2 18:22:13 2000\n\0"

and it is called thusly

	$asctime = asctime($sec, $min, $hour, $mday, $mon,
			   $year, $wday, $yday, $isdst);

The $mon is zero-based: January equals 0. The $year is 1900-based: 2001 equals 101. $wday and $yday default to zero (and are usually ignored anyway), and $isdst defaults to -1.

asin
This is identical to the C function asin(), returning the arcus sine of its numerical argument. See also Math::Trig.
asinh
This is identical to the C function asinh(), returning the hyperbolic arcus sine of its numerical argument [C99]. See also Math::Trig.
assert
Unimplemented, but you can use perlfunc/die and the Carp module to achieve similar things.
atan
This is identical to the C function atan(), returning the arcus tangent of its numerical argument. See also Math::Trig.
atanh
This is identical to the C function atanh(), returning the hyperbolic arcus tangent of its numerical argument [C99]. See also Math::Trig.
atan2
This is identical to Perl's builtin atan2() function, returning the arcus tangent defined by its two numerical arguments, the y coordinate and the x coordinate. See also Math::Trig.
atexit
Not implemented. atexit() is C-specific: use END {} instead, see perlmod.
atof
Not implemented. 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
Not implemented. 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 perlfunc/int.
atol
Not implemented. 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 perlfunc/int.
bsearch
bsearch() not supplied. For doing binary search on wordlists, see Search::Dict.
calloc
Not implemented. calloc() is C-specific. Perl does memory management transparently.
cbrt
The cube root [C99].
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 perlfunc/chdir.
chmod
This is identical to Perl's builtin chmod() function, allowing one to change file and directory permissions, see perlfunc/chmod.
chown
This is identical to Perl's builtin chown() function, allowing one to change file and directory owners and groups, see perlfunc/chown.
clearerr
Not implemented. 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 perlfunc/close.

closedir
This is identical to Perl's builtin closedir() function for closing a directory handle, see perlfunc/closedir.
cos
This is identical to Perl's builtin cos() function, for returning the cosine of its numerical argument, see perlfunc/cos. See also Math::Trig.
cosh
This is identical to the C function cosh(), for returning the hyperbolic cosine of its numeric argument. See also Math::Trig.
copysign

Returns x but with the sign of y [C99].

 $x_with_sign_of_y = POSIX::copysign($x, $y);

See also /signbit.

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 perlfunc/sysopen and its O_CREAT flag.

ctermid

Generates the path name for the controlling terminal.

	$path = POSIX::ctermid();
ctime
This is identical to the C function ctime() and equivalent to asctime(localtime(...)), see /asctime and /localtime.
cuserid

Get the login name of the owner of the current process.

	$name = POSIX::cuserid();
difftime
This is identical to the C function difftime(), for returning the time difference (in seconds) between two times (as returned by time()), see /time.
div
Not implemented. div() is C-specific, use perlfunc/int on the usual / division and the modulus %.
dup

This is similar to the C function dup(), for duplicating a file descriptor.

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

Returns undef on failure.

dup2

This is similar to the C function dup2(), for duplicating a file descriptor to an another known file descriptor.

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

Returns undef on failure.

erf
The error function [C99].
erfc
The complementary error function [C99].
errno

Returns the value of errno.

	$errno = POSIX::errno();

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

execl
Not implemented. execl() is C-specific, see perlfunc/exec.
execle
Not implemented. execle() is C-specific, see perlfunc/exec.
execlp
Not implemented. execlp() is C-specific, see perlfunc/exec.
execv
Not implemented. execv() is C-specific, see perlfunc/exec.
execve
Not implemented. execve() is C-specific, see perlfunc/exec.
execvp
Not implemented. execvp() is C-specific, see perlfunc/exec.
exit
This is identical to Perl's builtin exit() function for exiting the program, see perlfunc/exit.
exp
This is identical to Perl's builtin exp() function for returning the exponent (e-based) of the numerical argument, see perlfunc/exp.
expm1

Equivalent to exp(x) - 1, but more precise for small argument values [C99].

See also /log1p.

fabs
This is identical to Perl's builtin abs() function for returning the absolute value of the numerical argument, see perlfunc/abs.
fclose
Not implemented. Use method IO::Handle::close() instead, or see perlfunc/close.
fcntl
This is identical to Perl's builtin fcntl() function, see perlfunc/fcntl.
fdopen
Not implemented. Use method IO::Handle::new_from_fd() instead, or see perlfunc/open.
feof
Not implemented. Use method IO::Handle::eof() instead, or see perlfunc/eof.
ferror
Not implemented. Use method IO::Handle::error() instead.
fflush
Not implemented. Use method IO::Handle::flush() instead. See also perlvar/$OUTPUT_AUTOFLUSH.
fgetc
Not implemented. Use method IO::Handle::getc() instead, or see perlfunc/read.
fgetpos
Not implemented. Use method IO::Seekable::getpos() instead, or see perlfunc/seek.
fgets
Not implemented. Use method IO::Handle::gets() instead. Similar to <>, also known as perlfunc/readline.
fileno
Not implemented. Use method IO::Handle::fileno() instead, or see perlfunc/fileno.
floor
This is identical to the C function floor(), returning the largest integer value less than or equal to the numerical argument.
fdim
"Positive difference", x - y if x > y, zero otherwise [C99].
fegetround

Returns the current floating point rounding mode, one of

  FE_TONEAREST FE_TOWARDZERO FE_UPWARD FE_UPWARD

FE_TONEAREST is like /round, FE_TOWARDZERO is like /trunc [C99].

fesetround
Sets the floating point rounding mode, see /fegetround [C99].
fma

"Fused multiply-add", x * y + z, possibly faster (and less lossy) than the explicit two operations [C99].

 my $fused = POSIX::fma($x, $y, $z);
fmax

Maximum of x and y, except when either is NaN, returns the other [C99].

 my $min = POSIX::fmax($x, $y);
fmin

Minimum of x and y, except when either is NaN, returns the other [C99].

 my $min = POSIX::fmin($x, $y);
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
Not implemented. Use method IO::File::open() instead, or see perlfunc/open.
fork
This is identical to Perl's builtin fork() function for duplicating the current process, see perlfunc/fork and perlfork if you are in Windows.
fpathconf

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

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

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

Returns undef on failure.

fpclassify

Returns one of

  FP_NORMAL FP_ZERO FP_SUBNORMAL FP_INFINITE FP_NAN

telling the class of the argument [C99]. FP_INFINITE is positive or negative infinity, FP_NAN is not-a-number. FP_SUBNORMAL means subnormal numbers (also known as denormals), very small numbers with low precision. FP_ZERO is zero. FP_NORMAL is all the rest.

fprintf
Not implemented. fprintf() is C-specific, see perlfunc/printf instead.
fputc
Not implemented. fputc() is C-specific, see perlfunc/print instead.
fputs
Not implemented. fputs() is C-specific, see perlfunc/print instead.
fread
Not implemented. fread() is C-specific, see perlfunc/read instead.
free
Not implemented. free() is C-specific. Perl does memory management transparently.
freopen
Not implemented. freopen() is C-specific, see perlfunc/open instead.
frexp

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

	($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
fscanf
Not implemented. fscanf() is C-specific, use <> and regular expressions instead.
fseek
Not implemented. Use method IO::Seekable::seek() instead, or see perlfunc/seek.
fsetpos
Not implemented. Use method IO::Seekable::setpos() instead, or seek perlfunc/seek.
fstat

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

	$fd = POSIX::open( "foo", &POSIX::O_RDONLY );
	@stats = POSIX::fstat( $fd );
fsync
Not implemented. Use method IO::Handle::sync() instead.
ftell
Not implemented. Use method IO::Seekable::tell() instead, or see perlfunc/tell.
fwrite
Not implemented. fwrite() is C-specific, see perlfunc/print instead.
getc
This is identical to Perl's builtin getc() function, see perlfunc/getc.
getchar
Returns one character from STDIN. Identical to Perl's getc(), see perlfunc/getc.
getcwd
Returns the name of the current working directory. See also Cwd.
getegid
Returns the effective group identifier. Similar to Perl' s builtin variable $(, see perlvar/$EGID.
getenv
Returns the value of the specified environment variable. The same information is available through the %ENV array.
geteuid
Returns the effective user identifier. Identical to Perl's builtin $> variable, see perlvar/$EUID.
getgid
Returns the user's real group identifier. Similar to Perl's builtin variable $), see perlvar/$GID.
getgrgid
This is identical to Perl's builtin getgrgid() function for returning group entries by group identifiers, see perlfunc/getgrgid.
getgrnam
This is identical to Perl's builtin getgrnam() function for returning group entries by group names, see perlfunc/getgrnam.
getgroups
Returns the ids of the user's supplementary groups. Similar to Perl's builtin variable $), see perlvar/$GID.
getlogin
This is identical to Perl's builtin getlogin() function for returning the user name associated with the current session, see perlfunc/getlogin.
getpgrp
This is identical to Perl's builtin getpgrp() function for returning the process group identifier of the current process, see perlfunc/getpgrp.
getpid
Returns the process identifier. Identical to Perl's builtin variable $$, see perlvar/$PID.
getppid
This is identical to Perl's builtin getppid() function for returning the process identifier of the parent process of the current process , see perlfunc/getppid.
getpwnam
This is identical to Perl's builtin getpwnam() function for returning user entries by user names, see perlfunc/getpwnam.
getpwuid
This is identical to Perl's builtin getpwuid() function for returning user entries by user identifiers, see perlfunc/getpwuid.
gets

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

NOTE: if you have C programs that still use gets(), be very afraid. The gets() function is a source of endless grief because it has no buffer overrun checks. It should never be used. The fgets() function should be preferred instead.

getuid
Returns the user's identifier. Identical to Perl's builtin $< variable, see perlvar/$UID.
gmtime
This is identical to Perl's builtin gmtime() function for converting seconds since the epoch to a date in Greenwich Mean Time, see perlfunc/gmtime.
hypot
Equivalent to sqrt(x * x + y * y) except more stable on very large or very small arguments [C99].
ilogb

Integer binary logarithm [C99]

For example ilogb(20) is 4, as an integer.

See also /logb.

Inf

The infinity as a constant:

   use POSIX qw(Inf);
   my $pos_inf = +Inf;  # Or just Inf.
   my $neg_inf = -Inf;

See also /isinf, and /fpclassify.

isalnum

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:alnum:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

You may want to use the /\w/ construct instead.

isalpha

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:alpha:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

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

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:cntrl:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

isdigit

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:digit:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

You may want to use the /\d/ construct instead.

isfinite

Returns true if the argument is a finite number (that is, not an infinity, or the not-a-number) [C99].

See also /isinf, /isnan, and /fpclassify.

isgraph

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:graph:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

isgreater

(Also isgreaterequal, isless, islessequal, islessgreater, isunordered)

Floating point comparisons which handle the NaN [C99].

isinf

Returns true if the argument is an infinity (positive or negative) [C99].

See also /Inf, /isnan, /isfinite, and /fpclassify.

islower

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:lower:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

Do not use /[a-z]/ unless you don't care about the current locale.

isnan

Returns true if the argument is NaN (not-a-number) [C99].

Note that you cannot test for "NaN-ness" with

   $x == $x

since the NaN is not equivalent to anything, including itself.

See also /nan, /NaN, /isinf, and /fpclassify.

isnormal

Returns true if the argument is normal (that is, not a subnormal/denormal, and not an infinity, or a not-a-number) [C99].

See also /isfinite, and /fpclassify.

isprint

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:print:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

ispunct

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:punct:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

isspace

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:space:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

You may want to use the /\s/ construct instead.

isupper

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:upper:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

Do not use /[A-Z]/ unless you don't care about the current locale.

isxdigit

Deprecated function whose use raises a warning, and which is slated to be removed in a future Perl version. It is very similar to matching against qr/ ^ [[:xdigit:]]+ $ /x, which you should convert to use instead. The function is deprecated because 1) it doesn't handle UTF-8 encoded strings properly; and 2) it returns TRUE even if the input is the empty string. The function return is always based on the current locale, whereas using locale rules is optional with the regular expression, based on pragmas in effect and pattern modifiers (see perlre/Character set modifiers and perlre/Which character set modifier is in effect?).

The function returns TRUE if the input string is empty, or if the corresponding C function returns TRUE for every byte in the string.

j0
j1
jn
y0
y1
yn
The Bessel function of the first kind of the order zero.
kill
This is identical to Perl's builtin kill() function for sending signals to processes (often to terminate them), see perlfunc/kill.
labs
Not implemented. (For returning absolute values of long integers.) labs() is C-specific, see perlfunc/abs instead.
lchown

This is identical to the C function, except the order of arguments is consistent with Perl's builtin chown() with the added restriction of only one path, not a list of paths. Does the same thing as the chown() function but changes the owner of a symbolic link instead of the file the symbolic link points to.

 POSIX::lchown($uid, $gid, $file_path);
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
Not implemented. (For computing dividends of long integers.) ldiv() is C-specific, use / and int() instead.
lgamma

The logarithm of the Gamma function [C99].

See also /tgamma.

log1p
Equivalent to log(1 + x), but more stable results for small argument values [C99].
log2

Logarithm base two [C99].

See also /expm1.

logb

Integer binary logarithm [C99].

For example logb(20) is 4, as a floating point number.

See also /ilogb.

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

Get numeric formatting information. Returns a reference to a hash containing the current underlying locale's formatting values. Users of this function should also read perllocale, which provides a comprehensive discussion of Perl locale handling, including a section devoted to this function.

Here is how to query the database for the de (Deutsch or German) locale.

	my $loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
	print "Locale: \"$loc\"\n";
	my $lconv = POSIX::localeconv();
	foreach my $property (qw(
		decimal_point
		thousands_sep
		grouping
		int_curr_symbol
		currency_symbol
		mon_decimal_point
		mon_thousands_sep
		mon_grouping
		positive_sign
		negative_sign
		int_frac_digits
		frac_digits
		p_cs_precedes
		p_sep_by_space
		n_cs_precedes
		n_sep_by_space
		p_sign_posn
		n_sign_posn
		int_p_cs_precedes
		int_p_sep_by_space
		int_n_cs_precedes
		int_n_sep_by_space
		int_p_sign_posn
		int_n_sign_posn
	))
	{
		printf qq(%s: "%s",\n),
			$property, $lconv->{$property};
	}

The members whose names begin with int_p_ and int_n_ were added by POSIX.1-2008 and are only available on systems that support them.

localtime
This is identical to Perl's builtin localtime() function for converting seconds since the epoch to a date see perlfunc/localtime.
log
This is identical to Perl's builtin log() function, returning the natural (e-based) logarithm of the numerical argument, see perlfunc/log.
log10

This is identical to the C function log10(), returning the 10-base logarithm of the numerical argument. You can also use

    sub log10 { log($_[0]) / log(10) }

or

    sub log10 { log($_[0]) / 2.30258509299405 }

or

    sub log10 { log($_[0]) * 0.434294481903252 }
longjmp
Not implemented. longjmp() is C-specific: use perlfunc/die instead.
lseek

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

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

Returns undef on failure.

lrint

Depending on the current floating point rounding mode, rounds the argument either toward nearest (like /round), toward zero (like /trunc), downward (toward negative infinity), or upward (toward positive infinity) [C99].

For the rounding mode, see /fegetround.

lround

Like /round, but as integer, as opposed to floating point [C99].

See also /ceil, /floor, /trunc.

malloc
Not implemented. malloc() is C-specific. Perl does memory management transparently.
mblen

This is identical to the C function mblen().

Core Perl does not have any support for the wide and multibyte characters of the C standards, except under UTF-8 locales, so this might be a rather useless function.

However, Perl supports Unicode, see perluniintro.

mbstowcs

This is identical to the C function mbstowcs().

See /mblen.

mbtowc

This is identical to the C function mbtowc().

See /mblen.

memchr
Not implemented. memchr() is C-specific, see perlfunc/index instead.
memcmp
Not implemented. memcmp() is C-specific, use eq instead, see perlop.
memcpy
Not implemented. memcpy() is C-specific, use =, see perlop, or see perlfunc/substr.
memmove
Not implemented. memmove() is C-specific, use =, see perlop, or see perlfunc/substr.
memset
Not implemented. memset() is C-specific, use x instead, see perlop.
mkdir
This is identical to Perl's builtin mkdir() function for creating directories, see perlfunc/mkdir.
mkfifo

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

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

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

mktime

Convert date/time info to a calendar time.

Synopsis:

	mktime(sec, min, hour, mday, mon, year, wday = 0,
	       yday = 0, isdst = -1)

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

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

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

Returns undef on failure.

modf

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

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

See also /round.

NaN

The not-a-number as a constant:

   use POSIX qw(NaN);
   my $nan = NaN;

See also /nan, /isnan, and /fpclassify.

nan

Returns not-a-number [C99].

See also /isnan and /NaN.

nearbyint
Returns the nearest integer to the argument, according to the current rounding mode (see /fegetround) [C99].
nextafter

Returns the next representable floating point number after x in the direction of y [C99].

 my $nextafter = POSIX::nextafter($x, $y);

Like /nexttoward, but potentially less accurate.

nexttoward

Returns the next representable floating point number after x in the direction of y [C99].

 my $nexttoward = POSIX::nexttoward($x, $y);

Like /nextafter, but potentially more accurate.

nice

This is similar to the C function nice(), for changing the scheduling preference of the current process. Positive arguments mean a more polite process, negative values a more needy process. Normal (non-root) user processes can only change towards being more polite.

Returns undef on failure.

offsetof
Not implemented. offsetof() is C-specific, you probably want to see perlfunc/pack instead.
open

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

Open a file read-only with mode 0666.

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

Open a file for read and write.

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

Open a file for write, with truncation.

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

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

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

Returns undef on failure.

See also perlfunc/sysopen.

opendir

Open a directory for reading.

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

Returns undef on failure.

pathconf

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

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

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

Returns undef on failure.

pause

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

Returns undef on failure.

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

pow

Computes $x raised to the power $exponent.

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

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

printf
Formats and prints the specified arguments to STDOUT. See also perlfunc/printf.
putc
Not implemented. putc() is C-specific, see perlfunc/print instead.
putchar
Not implemented. putchar() is C-specific, see perlfunc/print instead.
puts
Not implemented. puts() is C-specific, see perlfunc/print instead.
qsort
Not implemented. qsort() is C-specific, see perlfunc/sort instead.
raise
Sends the specified signal to the current process. See also perlfunc/kill and the $$ in perlvar/$PID.
rand
Not implemented. rand() is non-portable, see perlfunc/rand instead.
read

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

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

Returns undef on failure.

See also perlfunc/sysread.

readdir
This is identical to Perl's builtin readdir() function for reading directory entries, see perlfunc/readdir.
realloc
Not implemented. realloc() is C-specific. Perl does memory management transparently.
remainder

Given x and y, returns the value x - n*y, where n is the integer closest to x/y. [C99]

 my $remainder = POSIX::remainder($x, $y)

See also /remquo.

remove
This is identical to Perl's builtin unlink() function for removing files, see perlfunc/unlink.
remquo

Like /remainder but also returns the low-order bits of the quotient (n) [C99]

(This is quite esoteric interface, mainly used to implement numerical algorithms.)

rename
This is identical to Perl's builtin rename() function for renaming files, see perlfunc/rename.
rewind
Seeks to the beginning of the file.
rewinddir
This is identical to Perl's builtin rewinddir() function for rewinding directory entry streams, see perlfunc/rewinddir.
rint
Identical to /lrint.
rmdir
This is identical to Perl's builtin rmdir() function for removing (empty) directories, see perlfunc/rmdir.
round

Returns the integer (but still as floating point) nearest to the argument [C99].

See also /ceil, /floor, /lround, /modf, and /trunc.

scalbn

Returns x * 2**y [C99].

See also /frexp and /ldexp.

scanf
Not implemented. scanf() is C-specific, use <> and regular expressions instead, see perlre.
setgid
Sets the real group identifier and the effective group identifier for this process. Similar to assigning a value to the Perl's builtin $) variable, see perlvar/$EGID, 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
Not implemented. setjmp() is C-specific: use eval {} instead, see perlfunc/eval.
setlocale

Modifies and queries the program's underlying locale. Users of this function should read perllocale, whch provides a comprehensive discussion of Perl locale handling, knowledge of which is necessary to properly use this function. It contains a section devoted to this function. The discussion here is merely a summary reference for setlocale(). Note that Perl itself is almost entirely unaffected by the locale except within the scope of "use locale". (Exceptions are listed in perllocale/Not within the scope of "use 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 system's setlocale(3) documentation for the locale environment variables' meaning or consult perllocale.

	$loc = setlocale( LC_CTYPE, "" );

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

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

This is similar to the C function setpgid() for setting the process group identifier of the current process.

Returns undef on failure.

setsid
This is identical to the C function setsid() for setting the session identifier of the current process.
setuid
Sets the real user identifier and the effective user identifier for this process. Similar to assigning a value to the Perl's builtin $< variable, see perlvar/$UID, except that the latter will change only the real user identifier.
sigaction

Detailed signal management. This uses POSIX::SigAction objects for the action and oldaction arguments (the oldaction can also be just a hash reference). Consult your system's sigaction manpage for details, see also POSIX::SigRt.

Synopsis:

	sigaction(signal, action, oldaction = 0)

Returns undef on failure. The signal must be a number (like SIGHUP), not a string (like "SIGHUP"), though Perl does try hard to understand you.

If you use the SA_SIGINFO flag, the signal handler will in addition to the first argument, the signal name, also receive a second argument, a hash reference, inside which are the following keys with the following semantics, as defined by POSIX/SUSv3:

    signo       the signal number
    errno       the error number
    code        if this is zero or less, the signal was sent by
                a user process and the uid and pid make sense,
                otherwise the signal was sent by the kernel

The following are also defined by POSIX/SUSv3, but unfortunately not very widely implemented:

    pid         the process id generating the signal
    uid         the uid of the process id generating the signal
    status      exit value or signal for SIGCHLD
    band        band event for SIGPOLL

A third argument is also passed to the handler, which contains a copy of the raw binary contents of the siginfo structure: if a system has some non-POSIX fields, this third argument is where to unpack() them from.

Note that not all siginfo values make sense simultaneously (some are valid only for certain signals, for example), and not all values make sense from Perl perspective, you should to consult your system's sigaction and possibly also siginfo documentation.

siglongjmp
Not implemented. siglongjmp() is C-specific: use perlfunc/die instead.
signbit
Returns zero for positive arguments, non-zero for negative arguments [C99].
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.

Note that you can't reliably block or unblock a signal from its own signal handler if you're using safe signals. Other signals can be blocked or unblocked reliably.

sigsetjmp
Not implemented. sigsetjmp() is C-specific: use eval {} instead, see perlfunc/eval.
sigsuspend

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

Synopsis:

	sigsuspend(signal_mask)

Returns undef on failure.

sin
This is identical to Perl's builtin sin() function for returning the sine of the numerical argument, see perlfunc/sin. See also Math::Trig.
sinh
This is identical to the C function sinh() for returning the hyperbolic sine of the numerical argument. See also Math::Trig.
sleep
This is functionally identical to Perl's builtin sleep() function for suspending the execution of the current for process for certain number of seconds, see perlfunc/sleep. There is one significant difference, however: POSIX::sleep() returns the number of unslept seconds, while the CORE::sleep() returns the number of slept seconds.
sprintf
This is similar to Perl's builtin sprintf() function for returning a string that has the arguments formatted as requested, see perlfunc/sprintf.
sqrt
This is identical to Perl's builtin sqrt() function. for returning the square root of the numerical argument, see perlfunc/sqrt.
srand
Give a seed the pseudorandom number generator, see perlfunc/srand.
sscanf
Not implemented. sscanf() is C-specific, use regular expressions instead, see perlre.
stat
This is identical to Perl's builtin stat() function for returning information about files and directories.
strcat
Not implemented. strcat() is C-specific, use .= instead, see perlop.
strchr
Not implemented. strchr() is C-specific, see perlfunc/index instead.
strcmp
Not implemented. strcmp() is C-specific, use eq or cmp instead, see perlop.
strcoll
This is identical to the C function strcoll() for collating (comparing) strings transformed using the strxfrm() function. Not really needed since Perl can do this transparently, see perllocale.
strcpy
Not implemented. strcpy() is C-specific, use = instead, see perlop.
strcspn
Not implemented. strcspn() is C-specific, use regular expressions instead, see perlre.
strerror
Returns the error string for the specified errno. Identical to the string form of $!, see perlvar/$ERRNO.
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
Not implemented. strlen() is C-specific, use length() instead, see perlfunc/length.
strncat
Not implemented. strncat() is C-specific, use .= instead, see perlop.
strncmp
Not implemented. strncmp() is C-specific, use eq instead, see perlop.
strncpy
Not implemented. strncpy() is C-specific, use = instead, see perlop.
strpbrk
Not implemented. strpbrk() is C-specific, use regular expressions instead, see perlre.
strrchr
Not implemented. strrchr() is C-specific, see perlfunc/rindex instead.
strspn
Not implemented. strspn() is C-specific, use regular expressions instead, see perlre.
strstr
This is identical to Perl's builtin index() function, see perlfunc/index.
strtod

String to double translation. Returns the parsed number and the number of characters in the unparsed portion of the string. Truly POSIX-compliant systems set $! ($ERRNO) to indicate a translation error, so clear $! before calling strtod. However, non-POSIX systems may not check for overflow, and therefore will never set $!.

strtod respects any POSIX setlocale() LC_TIME settings, regardless of whether or not it is called from Perl code that is within the scope of use locale.

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
Not implemented. strtok() is C-specific, use regular expressions instead, see perlre, or perlfunc/split.
strtol

String to (long) integer translation. Returns the parsed number and the number of characters in the unparsed portion of the string. Truly POSIX-compliant systems set $! ($ERRNO) to indicate a translation error, so clear $! before calling strtol. However, non-POSIX systems may not check for overflow, and therefore will never set $!.

strtol should respect any POSIX setlocale() settings.

To parse a string $str as a number in some base $base use

    $! = 0;
    ($num, $n_unparsed) = POSIX::strtol($str, $base);

The base should be zero or between 2 and 36, inclusive. When the base is zero or omitted strtol will use the string itself to determine the base: a leading "0x" or "0X" means hexadecimal; a leading "0" means octal; any other leading characters mean decimal. Thus, "1234" is parsed as a decimal number, "01234" as an octal number, and "0x1234" as a hexadecimal number.

The second returned item and $! can be used to check for valid input:

    if (($str eq '') || ($n_unparsed != 0) || !$!) {
        die "Non-numeric input $str" . $! ? ": $!\n" : "\n";
    }

When called in a scalar context strtol returns the parsed number.

strtold
Like /strtod but for long doubles. Defined only if the system supports long doubles.
strtoul

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

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

strxfrm

String transformation. Returns the transformed string.

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

Used in conjunction with the strcoll() function, see /strcoll.

Not really needed since Perl can do this transparently, see perllocale.

sysconf

Retrieves values of system configurable variables.

The following will get the machine's clock speed.

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

Returns undef on failure.

system
This is identical to Perl's builtin system() function, see perlfunc/system.
tan
This is identical to the C function tan(), returning the tangent of the numerical argument. See also Math::Trig.
tanh
This is identical to the C function tanh(), returning the hyperbolic tangent of the numerical argument. See also Math::Trig.
tcdrain

This is similar to the C function tcdrain() for draining the output queue of its argument stream.

Returns undef on failure.

tcflow

This is similar to the C function tcflow() for controlling the flow of its argument stream.

Returns undef on failure.

tcflush

This is similar to the C function tcflush() for flushing the I/O buffers of its argument stream.

Returns undef on failure.

tcgetpgrp
This is identical to the C function tcgetpgrp() for returning the process group identifier of the foreground process group of the controlling terminal.
tcsendbreak

This is similar to the C function tcsendbreak() for sending a break on its argument stream.

Returns undef on failure.

tcsetpgrp

This is similar to the C function tcsetpgrp() for setting the process group identifier of the foreground process group of the controlling terminal.

Returns undef on failure.

tgamma

The Gamma function [C99].

See also /lgamma.

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 perlfunc/time.
times

The times() function returns elapsed realtime since some point in the past (such as system startup), user and system times for this process, and user and system times used by child processes. All times are returned in clock ticks.

    ($realtime, $user, $system, $cuser, $csystem)
	= POSIX::times();

Note: Perl's builtin times() function returns four values, measured in seconds.

tmpfile
Not implemented. Use method IO::File::new_tmpfile() instead, or see File::Temp.
tmpnam

Returns a name for a temporary file.

	$tmpfile = POSIX::tmpnam();

For security reasons, which are probably detailed in your system's documentation for the C library tmpnam() function, this interface should not be used; instead see File::Temp.

tolower
This is identical to the C function, except that it can apply to a single character or to a whole string, and currently operates as if the locale always is "C". Consider using the lc() function, see perlfunc/lc, see perlfunc/lc, or the equivalent \L operator inside doublequotish strings.
toupper
This is similar to the C function, except that it can apply to a single character or to a whole string, and currently operates as if the locale always is "C". Consider using the uc() function, see perlfunc/uc, or the equivalent \U operator inside doublequotish strings.
trunc

Returns the integer toward zero from the argument [C99].

See also /ceil, /floor, and /round.

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 perlfunc/umask.
uname

Get name of current operating system.

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

Note that the actual meanings of the various fields are not that well standardized, do not expect any great portability. The $sysname might be the name of the operating system, the $nodename might be the name of the host, the $release might be the (major) release number of the operating system, the $version might be the (minor) release number of the operating system, and the $machine might be a hardware identifier. Maybe.

ungetc
Not implemented. Use method IO::Handle::ungetc() instead.
unlink
This is identical to Perl's builtin unlink() function for removing files, see perlfunc/unlink.
utime
This is identical to Perl's builtin utime() function for changing the time stamps of files and directories, see perlfunc/utime.
vfprintf
Not implemented. vfprintf() is C-specific, see perlfunc/printf instead.
vprintf
Not implemented. vprintf() is C-specific, see perlfunc/printf instead.
vsprintf
Not implemented. vsprintf() is C-specific, see perlfunc/sprintf instead.
wait
This is identical to Perl's builtin wait() function, see perlfunc/wait.
waitpid

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

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

This is identical to the C function wcstombs().

See /mblen.

wctomb

This is identical to the C function wctomb().

See /mblen.

write

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

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

Returns undef on failure.

See also perlfunc/syswrite.

CLASSES

POSIX::SigAction

new

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

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

This POSIX::SigAction object is intended for use with the POSIX::sigaction() function.

handler
mask
flags

accessor functions to get/set the values of a SigAction object.

	$sigset = $sigaction->mask;
	$sigaction->flags(&POSIX::SA_RESTART);
safe

accessor function for the "safe signals" flag of a SigAction object; see perlipc for general information on safe (a.k.a. "deferred") signals. If you wish to handle a signal safely, use this accessor to set the "safe" flag in the POSIX::SigAction object:

	$sigaction->safe(1);

You may also examine the "safe" flag on the output action object which is filled in when given as the third parameter to POSIX::sigaction():

	sigaction(SIGINT, $new_action, $old_action);
	if ($old_action->safe) {
	    # previous SIGINT handler used safe signals
	}

POSIX::SigRt

%SIGRT

A hash of the POSIX realtime signal handlers. It is an extension of the standard %SIG, the $POSIX::SIGRT{SIGRTMIN} is roughly equivalent to $SIG{SIGRTMIN}, but the right POSIX moves (see below) are made with the POSIX::SigSet and POSIX::sigaction instead of accessing the %SIG.

You can set the %POSIX::SIGRT elements to set the POSIX realtime signal handlers, use delete and exists on the elements, and use scalar on the %POSIX::SIGRT to find out how many POSIX realtime signals there are available (SIGRTMAX - SIGRTMIN + 1, the SIGRTMAX is a valid POSIX realtime signal).

Setting the %SIGRT elements is equivalent to calling this:

  sub new {
    my ($rtsig, $handler, $flags) = @_;
    my $sigset = POSIX::SigSet($rtsig);
    my $sigact = POSIX::SigAction->new($handler,$sigset,$flags);
    sigaction($rtsig, $sigact);
  }

The flags default to zero, if you want something different you can either use local on $POSIX::SigRt::SIGACTION_FLAGS, or you can derive from POSIX::SigRt and define your own new() (the tied hash STORE method of the %SIGRT calls new($rtsig, $handler, $SIGACTION_FLAGS), where the $rtsig ranges from zero to SIGRTMAX - SIGRTMIN + 1).

Just as with any signal, you can use sigaction($rtsig, undef, $oa) to retrieve the installed signal handler (or, rather, the signal action).

NOTE: whether POSIX realtime signals really work in your system, or whether Perl has been compiled so that it works with them, is outside of this discussion.

SIGRTMIN
Return the minimum POSIX realtime signal number available, or undef if no POSIX realtime signals are available.
SIGRTMAX
Return the maximum POSIX realtime signal number available, or undef if no POSIX realtime signals are available.

POSIX::SigSet

new

Create a new SigSet object. This object will be destroyed automatically when it is no longer needed. Arguments may be supplied to initialize the set.

Create an empty set.

	$sigset = POSIX::SigSet->new;

Create a set with SIGUSR1.

	$sigset = POSIX::SigSet->new( &POSIX::SIGUSR1 );
addset

Add a signal to a SigSet object.

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

Returns undef on failure.

delset

Remove a signal from the SigSet object.

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

Returns undef on failure.

emptyset

Initialize the SigSet object to be empty.

	$sigset->emptyset();

Returns undef on failure.

fillset

Initialize the SigSet object to include all signals.

	$sigset->fillset();

Returns undef on failure.

ismember

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

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

POSIX::Termios

new

Create a new Termios object. This object will be destroyed automatically when it is no longer needed. A Termios object corresponds to the termios C struct. new() mallocs a new one, getattr() fills it from a file descriptor, and setattr() sets a file descriptor's parameters to match Termios' contents.

	$termios = POSIX::Termios->new;
getattr

Get terminal control attributes.

Obtain the attributes for stdin.

	$termios->getattr( 0 ) # Recommended for clarity.
	$termios->getattr()

Obtain the attributes for stdout.

	$termios->getattr( 1 )

Returns undef on failure.

getcc

Retrieve a value from the c_cc field of a termios object. The c_cc field is an array so an index must be specified.

	$c_cc[1] = $termios->getcc(1);
getcflag

Retrieve the c_cflag field of a termios object.

	$c_cflag = $termios->getcflag;
getiflag

Retrieve the c_iflag field of a termios object.

	$c_iflag = $termios->getiflag;
getispeed

Retrieve the input baud rate.

	$ispeed = $termios->getispeed;
getlflag

Retrieve the c_lflag field of a termios object.

	$c_lflag = $termios->getlflag;
getoflag

Retrieve the c_oflag field of a termios object.

	$c_oflag = $termios->getoflag;
getospeed

Retrieve the output baud rate.

	$ospeed = $termios->getospeed;
setattr

Set terminal control attributes.

Set attributes immediately for stdout.

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

Returns undef on failure.

setcc

Set a value in the c_cc field of a termios object. The c_cc field is an array so an index must be specified.

	$termios->setcc( &POSIX::VEOF, 1 );
setcflag

Set the c_cflag field of a termios object.

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

Set the c_iflag field of a termios object.

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

Set the input baud rate.

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

Returns undef on failure.

setlflag

Set the c_lflag field of a termios object.

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

Set the c_oflag field of a termios object.

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

Set the output baud rate.

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

Returns undef on failure.

Baud rate values
B38400 B75 B200 B134 B300 B1800 B150 B0 B19200 B1200 B9600 B600 B4800 B50 B2400 B110
Terminal interface values
TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF
c_cc field values
VEOF VEOL VERASE VINTR VKILL VQUIT VSUSP VSTART VSTOP VMIN VTIME NCCS
c_cflag field values
CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD
c_iflag field values
BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK
c_lflag field values
ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP
c_oflag field values
OPOST

PATHNAME CONSTANTS

Constants
_PC_CHOWN_RESTRICTED _PC_LINK_MAX _PC_MAX_CANON _PC_MAX_INPUT _PC_NAME_MAX _PC_NO_TRUNC _PC_PATH_MAX _PC_PIPE_BUF _PC_VDISABLE

POSIX CONSTANTS

Constants
_POSIX_ARG_MAX _POSIX_CHILD_MAX _POSIX_CHOWN_RESTRICTED _POSIX_JOB_CONTROL _POSIX_LINK_MAX _POSIX_MAX_CANON _POSIX_MAX_INPUT _POSIX_NAME_MAX _POSIX_NGROUPS_MAX _POSIX_NO_TRUNC _POSIX_OPEN_MAX _POSIX_PATH_MAX _POSIX_PIPE_BUF _POSIX_SAVED_IDS _POSIX_SSIZE_MAX _POSIX_STREAM_MAX _POSIX_TZNAME_MAX _POSIX_VDISABLE _POSIX_VERSION

SYSTEM CONFIGURATION

Constants
_SC_ARG_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_JOB_CONTROL _SC_NGROUPS_MAX _SC_OPEN_MAX _SC_PAGESIZE _SC_SAVED_IDS _SC_STREAM_MAX _SC_TZNAME_MAX _SC_VERSION

ERRNO

Constants
E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF EBADMSG EBUSY ECANCELED ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ EDOM EDQUOT EEXIST EFAULT EFBIG EHOSTDOWN EHOSTUNREACH EIDRM EILSEQ EINPROGRESS EINTR EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINK EMSGSIZE ENAMETOOLONG ENETDOWN ENETRESET ENETUNREACH ENFILE ENOBUFS ENODATA ENODEV ENOENT ENOEXEC ENOLCK ENOLINK ENOMEM ENOMSG ENOPROTOOPT ENOSPC ENOSR ENOSTR ENOSYS ENOTBLK ENOTCONN ENOTDIR ENOTEMPTY ENOTRECOVERABLE ENOTSOCK ENOTSUP ENOTTY ENXIO EOPNOTSUPP EOTHER EOVERFLOW EOWNERDEAD EPERM EPFNOSUPPORT EPIPE EPROCLIM EPROTO EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART EROFS ESHUTDOWN ESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIME 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

FLOATING-POINT ENVIRONMENT

Constants
FE_DOWNWARD FE_TONEAREST FE_TOWARDZERO FE_UPWARD on systems that support them.

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 LC_MESSAGES on systems that support them.

MATH

Constants

HUGE_VAL

FP_ILOGB0 FP_ILOGBNAN FP_INFINITE FP_NAN FP_NORMAL FP_SUBNORMAL FP_ZERO INFINITY NAN Inf NaN M_1_PI M_2_PI M_2_SQRTPI M_E M_LN10 M_LN2 M_LOG10E M_LOG2E M_PI M_PI_2 M_PI_4 M_SQRT1_2 M_SQRT2 on systems with C99 support.

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(${^CHILD_ERROR_NATIVE}) returns true if the child process exited normally (exit() or by falling off the end of main())
WEXITSTATUS
WEXITSTATUS(${^CHILD_ERROR_NATIVE}) returns the normal exit status of the child process (only meaningful if WIFEXITED(${^CHILD_ERROR_NATIVE}) is true)
WIFSIGNALED
WIFSIGNALED(${^CHILD_ERROR_NATIVE}) returns true if the child process terminated because of a signal
WTERMSIG
WTERMSIG(${^CHILD_ERROR_NATIVE}) returns the signal the child process terminated for (only meaningful if WIFSIGNALED(${^CHILD_ERROR_NATIVE}) is true)
WIFSTOPPED
WIFSTOPPED(${^CHILD_ERROR_NATIVE}) returns true if the child process is currently stopped (can happen only if you specified the WUNTRACED flag to waitpid())
WSTOPSIG
WSTOPSIG(${^CHILD_ERROR_NATIVE}) returns the signal the child process was stopped for (only meaningful if WIFSTOPPED(${^CHILD_ERROR_NATIVE}) is true)