POSIX(3perl) Perl Programmers Reference Guide POSIX(3perl)
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;
my $sess_id = POSIX::setsid();
my $fd = POSIX::open($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 or almost 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.
The notation "[C99]" indicates functions that were added in the ISO/IEC
9899:1999 version of the C language standard. Some may not be available
on your system if it adheres to an earlier standard. Attempts to use
any missing one will result in a fatal runtime error message.
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 (except that
POSIX::abs() must be provided an explicit value (rather than
relying on an implicit $_):
$absolute_value = POSIX::abs(42); # good
$absolute_value = POSIX::abs(); # throws exception
"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. Added in Perl v5.22.
"alarm" This is identical to Perl's builtin alarm() function, either for
arming or disarming the "SIGARLM" timer, except that
POSIX::alarm() must be provided an explicit value (rather than
relying on an implicit $_):
POSIX::alarm(3) # good
POSIX::alarm() # throws exception
"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.
Note the result is always in English. Use "strftime" instead to
get a result suitable for the current locale. That function's
%c format yields the locale's preferred representation.
"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. Added in Perl v5.22.
"assert"
Unimplemented, but you can use "die" in perlfunc 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. Added in Perl v5.22.
"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 "int" in perlfunc.
"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 "int" in perlfunc.
"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]. Added in Perl v5.22.
"ceil" This is identical to the C function ceil(), returning the
smallest integer value greater than or equal to the given
numerical argument.
"chdir" This is identical to Perl's builtin chdir() function, allowing
one to change the working (default) directory -- see "chdir" in
perlfunc -- with the exception that POSIX::chdir() must be
provided an explicit value (rather than relying on an implicit
$_):
$rv = POSIX::chdir('path/to/dir'); # good
$rv = POSIX::chdir(); # throws exception
"chmod" This is identical to Perl's builtin chmod() function, allowing
one to change file and directory permissions -- see "chmod" in
perlfunc -- with the exception that POSIX::chmod() can only
change one file at a time (rather than a list of files):
$c = chmod 0664, $file1, $file2; # good
$c = POSIX::chmod 0664, $file1; # throws exception
$c = POSIX::chmod 0664, $file1, $file2; # throws exception
As with the built-in chmod(), $file may be a filename or a file
handle.
"chown" This is identical to Perl's builtin chown() function, allowing
one to change file and directory owners and groups, see "chown"
in perlfunc.
"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 "close" in perlfunc.
"closedir"
This is identical to Perl's builtin closedir() function for
closing a directory handle, see "closedir" in perlfunc.
"cos" This is identical to Perl's builtin cos() function for returning
the cosine of its numerical argument -- except that POSIX::cos()
must be provided with an explicit value (rather than relying on
an implicit $_):
$cosine = POSIX::cos(3); # good
$cosine = POSIX::cos(); # throws exception
See "cos" in perlfunc; 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]. Added in Perl
v5.22.
$x_with_sign_of_y = POSIX::copysign($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 "sysopen" in perlfunc 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" [POSIX.1-1988]
Get the login name of the owner of the current process.
$name = POSIX::cuserid();
Note: this function has not been specified by POSIX since 1990
and is included only for backwards compatibility. New code
should use getlogin() instead.
"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 "int" in perlfunc 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]. Added in Perl v5.22.
"erfc" The complementary error function [C99]. Added in Perl v5.22.
"errno" Returns the value of errno.
$errno = POSIX::errno();
This identical to the numerical values of the $!, see "$ERRNO"
in perlvar.
"execl" Not implemented. execl() is C-specific, see "exec" in perlfunc.
"execle"
Not implemented. execle() is C-specific, see "exec" in
perlfunc.
"execlp"
Not implemented. execlp() is C-specific, see "exec" in
perlfunc.
"execv" Not implemented. execv() is C-specific, see "exec" in perlfunc.
"execve"
Not implemented. execve() is C-specific, see "exec" in
perlfunc.
"execvp"
Not implemented. execvp() is C-specific, see "exec" in
perlfunc.
"exit" This is identical to Perl's builtin exit() function for exiting
the program, see "exit" in perlfunc.
"exp" This is identical to Perl's builtin exp() function for returning
the exponent (e-based) of the numerical argument -- except that
POSIX::exp() must be provided with an explicit value (rather
than relying on an implicit $_):
$exp = POSIX::exp(3); # good
$exp = POSIX::exp(); # throws exception
See "exp" in perlfunc.
"expm1" Equivalent to "exp(x) - 1", but more precise for small argument
values [C99]. Added in Perl v5.22.
See also "log1p".
"fabs" This is identical to Perl's builtin abs() function for returning
the absolute value of the numerical argument -- except that
POSIX::fabs() must be provided with an explicit value (rather
than relying on an implicit $_):
$absolute_value = POSIX::fabs(3); # good
$absolute_value = POSIX::fabs(); # throws exception
See "abs" in perlfunc.
This is identical to Perl's builtin cos() function for returning
the cosine =item "fclose"
Not implemented. Use method IO::Handle::close() instead, or see
"close" in perlfunc.
"fcntl" This is identical to Perl's builtin fcntl() function, see
"fcntl" in perlfunc.
"fdopen"
Not implemented. Use method IO::Handle::new_from_fd() instead,
or see "open" in perlfunc.
"feof" Not implemented. Use method IO::Handle::eof() instead, or see
"eof" in perlfunc.
"ferror"
Not implemented. Use method IO::Handle::error() instead.
"fflush"
Not implemented. Use method IO::Handle::flush() instead. See
also ""$OUTPUT_AUTOFLUSH" in perlvar".
"fgetc" Not implemented. Use method IO::Handle::getc() instead, or see
"read" in perlfunc.
"fgetpos"
Not implemented. Use method IO::Seekable::getpos() instead, or
see "seek" in perlfunc.
"fgets" Not implemented. Use method IO::Handle::gets() instead.
Similar to <>, also known as "readline" in perlfunc.
"fileno"
Not implemented. Use method IO::Handle::fileno() instead, or
see "fileno" in perlfunc.
"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].
Added in Perl v5.22.
"fegetround"
Returns the current floating point rounding mode, one of
FE_TONEAREST FE_TOWARDZERO FE_UPWARD FE_DOWNWARD
"FE_TONEAREST" is like "round", "FE_TOWARDZERO" is like "trunc"
[C99]. Added in Perl v5.22.
"fesetround"
Sets the floating point rounding mode, see "fegetround" [C99].
Added in Perl v5.22.
"fma" "Fused multiply-add", "x * y + z", possibly faster (and less
lossy) than the explicit two operations [C99]. Added in Perl
v5.22.
my $fused = POSIX::fma($x, $y, $z);
"fmax" Maximum of "x" and "y", except when either is "NaN", returns the
other [C99]. Added in Perl v5.22.
my $max = POSIX::fmax($x, $y);
"fmin" Minimum of "x" and "y", except when either is "NaN", returns the
other [C99]. Added in Perl v5.22.
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
"open" in perlfunc.
"fork" This is identical to Perl's builtin fork() function for
duplicating the current process, see "fork" in perlfunc 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. Added in Perl v5.22.
"fprintf"
Not implemented. fprintf() is C-specific, see "printf" in
perlfunc instead.
"fputc" Not implemented. fputc() is C-specific, see "print" in perlfunc
instead.
"fputs" Not implemented. fputs() is C-specific, see "print" in perlfunc
instead.
"fread" Not implemented. fread() is C-specific, see "read" in perlfunc
instead.
"free" Not implemented. free() is C-specific. Perl does memory
management transparently.
"freopen"
Not implemented. freopen() is C-specific, see "open" in
perlfunc 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 "seek" in perlfunc.
"fsetpos"
Not implemented. Use method IO::Seekable::setpos() instead, or
seek "seek" in perlfunc.
"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 "tell" in perlfunc.
"fwrite"
Not implemented. fwrite() is C-specific, see "print" in
perlfunc instead.
"getc" This is identical to Perl's builtin getc() function, see "getc"
in perlfunc.
"getchar"
Returns one character from STDIN. Identical to Perl's getc(),
see "getc" in perlfunc.
"getcwd"
Returns the name of the current working directory. See also
Cwd.
"getegid"
Returns the effective group identifier. Similar to Perl' s
builtin variable $(, see "$EGID" in perlvar.
"getenv"
Returns the value of the specified environment variable. The
same information is available through the %ENV array.
"geteuid"
Returns the effective user identifier. Identical to Perl's
builtin $> variable, see "$EUID" in perlvar.
"getgid"
Returns the user's real group identifier. Similar to Perl's
builtin variable $), see "$GID" in perlvar.
"getgrgid"
This is identical to Perl's builtin getgrgid() function for
returning group entries by group identifiers, see "getgrgid" in
perlfunc.
"getgrnam"
This is identical to Perl's builtin getgrnam() function for
returning group entries by group names, see "getgrnam" in
perlfunc.
"getgroups"
Returns the ids of the user's supplementary groups. Similar to
Perl's builtin variable $), see "$GID" in perlvar.
"getlogin"
This is identical to Perl's builtin getlogin() function for
returning the user name associated with the current session, see
"getlogin" in perlfunc.
"getpayload"
use POSIX ':nan_payload';
getpayload($var)
Returns the "NaN" payload. Added in Perl v5.24.
Note the API instability warning in "setpayload".
See "nan" for more discussion about "NaN".
"getpgrp"
This is identical to Perl's builtin getpgrp() function for
returning the process group identifier of the current process,
see "getpgrp" in perlfunc.
"getpid"
Returns the process identifier. Identical to Perl's builtin
variable $$, see "$PID" in perlvar.
"getppid"
This is identical to Perl's builtin getppid() function for
returning the process identifier of the parent process of the
current process , see "getppid" in perlfunc.
"getpwnam"
This is identical to Perl's builtin getpwnam() function for
returning user entries by user names, see "getpwnam" in
perlfunc.
"getpwuid"
This is identical to Perl's builtin getpwuid() function for
returning user entries by user identifiers, see "getpwuid" in
perlfunc.
"gets" Returns one line from "STDIN", similar to <>, also known as the
readline() function, see "readline" in perlfunc.
NOTE: if you have C programs that still use gets(), be very
afraid. The gets() function is a source of endless grief
because it has no buffer overrun checks. It should never be
used. The fgets() function should be preferred instead.
"getuid"
Returns the user's identifier. Identical to Perl's builtin $<
variable, see "$UID" in perlvar.
"gmtime"
This is identical to Perl's builtin gmtime() function for
converting seconds since the epoch to a date in Greenwich Mean
Time, see "gmtime" in perlfunc.
"hypot" Equivalent to sqrt(x * x + y * y) except more stable on very
large or very small arguments [C99]. Added in Perl v5.22.
"ilogb" Integer binary logarithm [C99]. Added in Perl v5.22.
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"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:alnum:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isalpha"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:alpha:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isatty"
Returns a boolean indicating whether the specified filehandle is
connected to a tty. Similar to the "-t" operator, see "-X" in
perlfunc.
"iscntrl"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:cntrl:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isdigit"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:digit:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isfinite"
Returns true if the argument is a finite number (that is, not an
infinity, or the not-a-number) [C99]. Added in Perl v5.22.
See also "isinf", "isnan", and "fpclassify".
"isgraph"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:graph:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isgreater"
(Also "isgreaterequal", "isless", "islessequal",
"islessgreater", "isunordered")
Floating point comparisons which handle the "NaN" [C99]. Added
in Perl v5.22.
"isinf" Returns true if the argument is an infinity (positive or
negative) [C99]. Added in Perl v5.22.
See also "Inf", "isnan", "isfinite", and "fpclassify".
"islower"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:lower:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isnan" Returns true if the argument is "NaN" (not-a-number) [C99].
Added in Perl v5.22.
Note that you can also test for ""NaN"-ness" with equality
operators ("==" or "!="), as in
print "x is not a NaN\n" if $x == $x;
since the "NaN" is not equal 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]. Added in Perl v5.22.
See also "isfinite", and "fpclassify".
"isprint"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:print:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"ispunct"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:punct:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"issignaling"
use POSIX ':nan_payload';
issignaling($var, $payload)
Return true if the argument is a signaling NaN. Added in Perl
v5.24.
Note the API instability warning in "setpayload".
See "nan" for more discussion about "NaN".
"isspace"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:space:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isupper"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:upper:]]+ $ /x", which you
should convert to use instead. See "POSIX Character Classes" in
perlrecharclass.
"isxdigit"
This function has been removed as of Perl v5.24. It was very
similar to matching against "qr/ ^ [[:xdigit:]]+ $ /x", which
you should convert to use instead. See "POSIX Character
Classes" in perlrecharclass.
"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 "kill" in
perlfunc.
"labs" Not implemented. (For returning absolute values of long
integers.) labs() is C-specific, see "abs" in perlfunc 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]. Added in Perl v5.22.
See also "tgamma".
"log1p" Equivalent to "log(1 + x)", but more stable results for small
argument values [C99]. Added in Perl v5.22.
"log2" Logarithm base two [C99]. Added in Perl v5.22.
See also "expm1".
"logb" Integer binary logarithm [C99]. Added in Perl v5.22.
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 "link" in perlfunc.
"localeconv"
Get numeric formatting information. Returns a reference to a
hash containing the formatting values of the locale that
currently underlies the program, regardless of whether or not it
is called from within the scope of a "use locale". Users of
this function should also read perllocale, which provides a
comprehensive discussion of Perl locale handling, including a
section devoted to this function. Prior to Perl 5.28, or when
operating in a non thread-safe environment, it should not be
used in a threaded application unless it's certain that the
underlying locale is C or POSIX. This is because it otherwise
changes the locale, which globally affects all threads
simultaneously. Windows platforms starting with Visual Studio
2005 are mostly thread-safe, but use of this function in those
prior to Visual Studio 2015 can have a race with a thread that
has called "switch_to_global_locale" in perlapi.
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.
A value of -1 returned for numeric entries indicates that the
field is not applicable to the locale. This is rare except in
the C and related locales, which don't have most monetary values
defined. It can also happen, quirkily, in fields that are
otherwise boolean to indicate that the value is kind of neither
true nor false. This happens in "p_cs_precedes" and
"int_p_cs_precedes" when the currency symbol neither precedes
nor succeeds a positive value but is infixed, by replacing the
radix character.
Prior to Perl v5.37.7, empty string fields and numeric fields
with value -1 were omittted from the returned hash.
"localtime"
This is identical to Perl's builtin localtime() function for
converting seconds since the epoch to a date see "localtime" in
perlfunc except that POSIX::localtime() must be provided an
explicit value (rather than relying on an implicit $_):
@localtime = POSIX::localtime(time); # good
@localtime = localtime(); # good
@localtime = POSIX::localtime(); # throws exception
"log" This is identical to Perl's builtin log() function for returning
the natural (e-based) logarithm of the numerical argument --
except that POSIX::log() must be provided with an explicit value
(rather than relying on an implicit $_):
$log = POSIX::log(3); # good
$log = POSIX::log(); # throws exception
See "log" in perlfunc.
"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 "die" in perlfunc
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]. Added in Perl v5.22.
For the rounding mode, see "fegetround".
"lround"
Like "round", but as integer, as opposed to floating point
[C99]. Added in Perl v5.22.
See also "ceil", "floor", "trunc".
Owing to an oversight, this is not currently exported by
default, or as part of the ":math_h_c99" export tag; importing
it must therefore be done by explicit name.
"malloc"
Not implemented. malloc() is C-specific. Perl does memory
management transparently.
"mblen" This is the same as the C function mblen() on unthreaded perls.
On threaded perls, it transparently (almost) substitutes the
more thread-safe "mbrlen"(3), if available, instead of "mblen".
Core Perl does not have any support for wide and multibyte
locales, except Unicode UTF-8 locales. This function, in
conjunction with "mbtowc" and "wctomb" may be used to roll your
own decoding/encoding of other types of multi-byte locales.
Use "undef" as the first parameter to this function to get the
effect of passing NULL as the first parameter to "mblen". This
resets any shift state to its initial value. The return value
is undefined if "mbrlen" was substituted, so you should never
rely on it.
When the first parameter is a scalar containing a value that
either is a PV string or can be forced into one, the return
value is the number of bytes occupied by the first character of
that string; or 0 if that first character is the wide NUL
character; or negative if there is an error. This is based on
the locale that currently underlies the program, regardless of
whether or not the function is called from Perl code that is
within the scope of "use locale". Perl makes no attempt at
hiding from your code any differences in the "errno" setting
between "mblen" and "mbrlen". It does set "errno" to 0 before
calling them.
The optional second parameter is ignored if it is larger than
the actual length of the first parameter string.
"mbtowc"
This is the same as the C function mbtowc() on unthreaded perls.
On threaded perls, it transparently (almost) substitutes the
more thread-safe "mbrtowc"(3), if available, instead of
"mbtowc".
Core Perl does not have any support for wide and multibyte
locales, except Unicode UTF-8 locales. This function, in
conjunction with "mblen" and "wctomb" may be used to roll your
own decoding/encoding of other types of multi-byte locales.
The first parameter is a scalar into which, upon success, the
wide character represented by the multi-byte string contained in
the second parameter is stored. The optional third parameter is
ignored if it is larger than the actual length of the second
parameter string.
Use "undef" as the second parameter to this function to get the
effect of passing NULL as the second parameter to "mbtowc".
This ignores the first parameter, and resets any shift state to
its initial value. The return value is undefined if "mbrtowc"
was substituted, so you should never rely on it.
When the second parameter is a scalar containing a value that
either is a PV string or can be forced into one, the return
value is the number of bytes occupied by the first character of
that string; or 0 if that first character is the wide NUL
character; or negative if there is an error. This is based on
the locale that currently underlies the program, regardless of
whether or not the function is called from Perl code that is
within the scope of "use locale". Perl makes no attempt at
hiding from your code any differences in the "errno" setting
between "mbtowc" and "mbrtowc". It does set "errno" to 0 before
calling them.
"memchr"
Not implemented. memchr() is C-specific, see "index" in
perlfunc 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 "substr" in perlfunc.
"memmove"
Not implemented. memmove() is C-specific, use "=", see perlop,
or see "substr" in perlfunc.
"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 "mkdir" in perlfunc.
"mkfifo"
This is similar to the C function mkfifo() for creating FIFO
special files.
if (mkfifo($path, $mode)) { ....
Returns "undef" on failure. The $mode is similar to the mode of
mkdir(), see "mkdir" in perlfunc, 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"
my $nan = nan();
Returns "NaN", not-a-number [C99]. Added in Perl v5.22.
The returned NaN is always a quiet NaN, as opposed to signaling.
With an argument, can be used to generate a NaN with payload.
The argument is first interpreted as a floating point number,
but then any fractional parts are truncated (towards zero), and
the value is interpreted as an unsigned integer. The bits of
this integer are stored in the unused bits of the NaN.
The result has a dual nature: it is a NaN, but it also carries
the integer inside it. The integer can be retrieved with
"getpayload". Note, though, that the payload is not propagated,
not even on copies, and definitely not in arithmetic operations.
How many bits fit in the NaN depends on what kind of floating
points are being used, but on the most common platforms (64-bit
IEEE 754, or the x86 80-bit long doubles) there are 51 and 61
bits available, respectively. (There would be 52 and 62, but
the quiet/signaling bit of NaNs takes away one.) However,
because of the floating-point-to- integer-and-back conversions,
please test carefully whether you get back what you put in. If
your integers are only 32 bits wide, you probably should not
rely on more than 32 bits of payload.
Whether a "signaling" NaN is in any way different from a "quiet"
NaN, depends on the platform. Also note that the payload of the
default NaN (no argument to nan()) is not necessarily zero, use
"setpayload" to explicitly set the payload. On some platforms
like the 32-bit x86, (unless using the 80-bit long doubles) the
signaling bit is not supported at all.
See also "isnan", "NaN", "setpayload" and "issignaling".
"nearbyint"
Returns the nearest integer to the argument, according to the
current rounding mode (see "fegetround") [C99]. Added in Perl
v5.22.
"nextafter"
Returns the next representable floating point number after "x"
in the direction of "y" [C99]. Added in Perl v5.22.
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]. Added in Perl v5.22.
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 "pack" in perlfunc instead.
"open" Open a file for reading for writing. This returns file
descriptors, not Perl filehandles. Use "POSIX::close" to close
the file.
Open a file read-only with mode 0666.
$fd = POSIX::open( "foo" );
Open a file for read and write.
$fd = POSIX::open( "foo", &POSIX::O_RDWR );
Open a file for write, with truncation.
$fd = POSIX::open(
"foo", &POSIX::O_WRONLY | &POSIX::O_TRUNC
);
Create a new file with mode 0640. Set up the file for writing.
$fd = POSIX::open(
"foo", &POSIX::O_CREAT | &POSIX::O_WRONLY, 0640
);
Returns "undef" on failure.
See also "sysopen" in perlfunc.
"opendir"
Open a directory for reading.
$dir = POSIX::opendir( "/var" );
@files = POSIX::readdir( $dir );
POSIX::closedir( $dir );
Returns "undef" on failure.
"pathconf"
Retrieves the value of a configurable limit on a file or
directory.
The following will determine the maximum length of the longest
allowable pathname on the filesystem which holds "/var".
$path_max = POSIX::pathconf( "/var",
&POSIX::_PC_PATH_MAX );
Returns "undef" on failure.
"pause" This is similar to the C function pause(), which suspends the
execution of the current process until a signal is received.
Returns "undef" on failure.
"perror"
This is identical to the C function perror(), which outputs to
the standard error stream the specified message followed by ": "
and the current error string. Use the warn() function and the
$! variable instead, see "warn" in perlfunc and "$ERRNO" in
perlvar.
"pipe" Create an interprocess channel. This returns file descriptors
like those returned by "POSIX::open".
my ($read, $write) = POSIX::pipe();
POSIX::write( $write, "hello", 5 );
POSIX::read( $read, $buf, 5 );
See also "pipe" in perlfunc.
"pow" Computes $x raised to the power $exponent.
$ret = POSIX::pow( $x, $exponent );
You can also use the "**" operator, see perlop.
"printf"
Formats and prints the specified arguments to "STDOUT". See
also "printf" in perlfunc.
"putc" Not implemented. putc() is C-specific, see "print" in perlfunc
instead.
"putchar"
Not implemented. putchar() is C-specific, see "print" in
perlfunc instead.
"puts" Not implemented. puts() is C-specific, see "print" in perlfunc
instead.
"qsort" Not implemented. qsort() is C-specific, see "sort" in perlfunc
instead.
"raise" Sends the specified signal to the current process. See also
"kill" in perlfunc and the $$ in "$PID" in perlvar.
"rand" Not implemented. rand() is non-portable, see "rand" in perlfunc
instead.
"read" Read from a file. This uses file descriptors such as those
obtained by calling "POSIX::open". If the buffer $buf is not
large enough for the read then Perl will extend it to make room
for the request.
$fd = POSIX::open( "foo", &POSIX::O_RDONLY );
$bytes = POSIX::read( $fd, $buf, 3 );
Returns "undef" on failure.
See also "sysread" in perlfunc.
"readdir"
This is identical to Perl's builtin readdir() function for
reading directory entries, see "readdir" in perlfunc.
"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]. Added in Perl v5.22.
my $remainder = POSIX::remainder($x, $y)
See also "remquo".
"remove"
Deletes a name from the filesystem. Calls "unlink" in perlfunc
for files and "rmdir" in perlfunc for directories.
"remquo"
Like "remainder" but also returns the low-order bits of the
quotient (n) [C99]. Added in Perl v5.22.
(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 "rename" in perlfunc.
"rewind"
Seeks to the beginning of the file.
"rewinddir"
This is identical to Perl's builtin rewinddir() function for
rewinding directory entry streams, see "rewinddir" in perlfunc.
"rint" Identical to "lrint".
"rmdir" This is identical to Perl's builtin rmdir() function for
removing (empty) directories, see "rmdir" in perlfunc.
"round" Returns the integer (but still as floating point) nearest to the
argument [C99]. Added in Perl v5.22.
See also "ceil", "floor", "lround", "modf", and "trunc".
"scalbn"
Returns "x * 2**y" [C99]. Added in Perl v5.22.
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 $) variable, see "$EGID" in perlvar, except
that the latter will change only the real user identifier, and
that the setgid() uses only a single numeric argument, as
opposed to a space-separated list of numbers.
"setjmp"
Not implemented. setjmp() is C-specific: use "eval {}" instead,
see "eval" in perlfunc.
"setlocale"
WARNING! Prior to Perl 5.28 or on a system that does not
support thread-safe locale operations, do NOT use this function
in a thread. The locale will change in all other threads at the
same time, and should your thread get paused by the operating
system, and another started, that thread will not have the
locale it is expecting. On some platforms, there can be a race
leading to segfaults if two threads call this function nearly
simultaneously. This warning does not apply on unthreaded
builds, or on perls where "${^SAFE_LOCALES}" exists and is non-
zero; namely Perl 5.28 and later compiled to be locale-thread-
safe.
This function 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
"Not within the scope of "use locale"" in perllocale, and
locale-dependent functions within the POSIX module ARE always
affected by the current 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.
$loc = setlocale( LC_COLLATE, "es_AR.ISO8859-1" );
"setpayload"
use POSIX ':nan_payload';
setpayload($var, $payload);
Sets the "NaN" payload of var. Added in Perl v5.24.
NOTE: the NaN payload APIs are based on the latest (as of June
2015) proposed ISO C interfaces, but they are not yet a
standard. Things may change.
See "nan" for more discussion about "NaN".
See also "setpayloadsig", "isnan", "getpayload", and
"issignaling".
"setpayloadsig"
use POSIX ':nan_payload';
setpayloadsig($var, $payload);
Like "setpayload" but also makes the NaN signaling. Added in
Perl v5.24.
Depending on the platform the NaN may or may not behave
differently.
Note the API instability warning in "setpayload".
Note that because how the floating point formats work out, on
the most common platforms signaling payload of zero is best
avoided, since it might end up being identical to "+Inf".
See also "nan", "isnan", "getpayload", and "issignaling".
"setpgid"
This is similar to the C function setpgid() for setting the
process group identifier of the current process.
Returns "undef" on failure.
"setsid"
This is identical to the C function setsid() for setting the
session identifier of the current process.
"setuid"
Sets the real user identifier and the effective user identifier
for this process. Similar to assigning a value to the Perl's
builtin $< variable, see "$UID" in perlvar, except that the
latter will change only the real user identifier.
"sigaction"
Detailed signal management. This uses "POSIX::SigAction"
objects for the "action" and "oldaction" arguments (the
oldaction can also be just a hash reference). Consult your
system's "sigaction" manpage for details, see also
"POSIX::SigRt".
Synopsis:
sigaction(signal, action, oldaction = 0)
Returns "undef" on failure. The "signal" must be a number (like
"SIGHUP"), not a string (like "SIGHUP"), though Perl does try
hard to understand you.
If you use the "SA_SIGINFO" flag, the signal handler will in
addition to the first argument, the signal name, also receive a
second argument, a hash reference, inside which are the
following keys with the following semantics, as defined by
POSIX/SUSv3:
signo the signal number
errno the error number
code if this is zero or less, the signal was sent by
a user process and the uid and pid make sense,
otherwise the signal was sent by the kernel
The constants for specific "code" values can be imported
individually or using the ":signal_h_si_code" tag, since Perl
v5.24.
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
addr address of faulting instruction or memory
reference for SIGILL, SIGFPE, SIGSEGV or SIGBUS
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 "die" in
perlfunc instead.
"signbit"
Returns zero for positive arguments, non-zero for negative
arguments [C99]. Added in Perl v5.22.
"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 "eval" in perlfunc.
"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 its numerical argument -- except that
POSIX::sin() must be provided with an explicit value (rather
than relying on an implicit $_):
$sine = POSIX::sin(3); # good
$sine = POSIX::sin(); # throws exception
See "sin" in perlfunc; see also Math::Trig.
"sinh" This is identical to the C function sinh() for returning the
hyperbolic sine of the numerical argument. See also Math::Trig.
"sleep" This is functionally identical to Perl's builtin sleep()
function for suspending the execution of the current for process
for certain number of seconds, see "sleep" in perlfunc. There
is one significant difference, however: POSIX::sleep() returns
the number of unslept seconds, while the CORE::sleep() returns
the number of slept seconds.
"sprintf"
This is similar to Perl's builtin sprintf() function for
returning a string that has the arguments formatted as
requested, see "sprintf" in perlfunc.
"sqrt" This is identical to Perl's builtin sqrt() function for
returning the square root of the numerical argument -- except
that POSIX::sqrt() must be provided with an explicit value
(rather than relying on an implicit $_):
$square_root = POSIX::sqrt(3); # good
$square_root = POSIX::sqrt(); # throws exception
See "sqrt" in perlfunc.
"srand" Give a seed the pseudorandom number generator, see "srand" in
perlfunc.
"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 "index" in
perlfunc 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.
Beware that in a UTF-8 locale, anything you pass to this
function must be in UTF-8; and when not in a UTF-8 locale,
anything passed must not be UTF-8 encoded.
Note also that it doesn't make sense for a string to be encoded
in one locale (say, ISO-8859-6, Arabic) and to collate it based
on another (like ISO-8859-7, Greek). The results will be
essentially meaningless.
"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 $!, see "$ERRNO" in perlvar.
"strftime"
Convert date and time information to string based on the current
underlying locale of the program (except for any daylight
savings time). Returns the string.
Synopsis:
strftime(fmt, sec, min, hour, mday, mon, year,
wday = -1, yday = -1, isdst = -1)
The month ("mon") begins at zero, e.g., January is 0, not 1.
The year ("year") is given in years since 1900, e.g., the year
1995 is 95; the year 2001 is 101. Consult your system's
strftime() manpage for details about these and the other
arguments.
The "wday", "yday", and "isdst" parameters are all ignored.
If you want your code to be portable, your format ("fmt")
argument should use only the conversion specifiers defined by
the ANSI C standard (C99, 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, so that the
returned value will always be as if the locale doesn't have
daylight savings time.
The string for Tuesday, December 12, 1995 in the "C" locale.
$str = POSIX::strftime( "%A, %B %d, %Y",
0, 0, 0, 12, 11, 95, 2 );
print "$str\n";
"strlen"
Not implemented. strlen() is C-specific, use length() instead,
see "length" in perlfunc.
"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 "rindex" in
perlfunc 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
"index" in perlfunc.
"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_NUMERIC" settings,
regardless of whether or not it is called from Perl code that is
within the scope of "use locale". Prior to Perl 5.28, or when
operating in a non thread-safe environment, it should not be
used in a threaded application unless it's certain that the
underlying locale is C or POSIX. This is because it otherwise
changes the locale, which globally affects all threads
simultaneously.
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 "split" in perlfunc.
"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 with "eq" or "cmp" as an alternative to "strcoll".
Not really needed since Perl can do this transparently, see
perllocale.
Unlike the libc "strxfrm", this allows NUL characters in the
input $src.
It doesn't make sense for a string to be encoded in one locale
(say, ISO-8859-6, Arabic) and to collate it based on another
(like ISO-8859-7, Greek). Perl assumes that the current
"LC_CTYPE" locale correctly represents the encoding of $src, and
ignores the value of "LC_COLLATE".
"sysconf"
Retrieves values of system configurable variables.
The following will get the machine's clock speed.
$clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
Returns "undef" on failure.
"system"
This is identical to Perl's builtin system() function, see
"system" in perlfunc.
"tan" This is identical to the C function tan(), returning the tangent
of the numerical argument. See also Math::Trig.
"tanh" This is identical to the C function tanh(), returning the
hyperbolic tangent of the numerical argument. See also
Math::Trig.
"tcdrain"
This is similar to the C function tcdrain() for draining the
output queue of its argument stream.
Returns "undef" on failure.
"tcflow"
This is similar to the C function tcflow() for controlling the
flow of its argument stream.
Returns "undef" on failure.
"tcflush"
This is similar to the C function tcflush() for flushing the I/O
buffers of its argument stream.
Returns "undef" on failure.
"tcgetpgrp"
This is identical to the C function tcgetpgrp() for returning
the process group identifier of the foreground process group of
the controlling terminal.
"tcsendbreak"
This is similar to the C function tcsendbreak() for sending a
break on its argument stream.
Returns "undef" on failure.
"tcsetpgrp"
This is similar to the C function tcsetpgrp() for setting the
process group identifier of the foreground process group of the
controlling terminal.
Returns "undef" on failure.
"tgamma"
The Gamma function [C99]. Added in Perl v5.22.
See also "lgamma".
"time" This is identical to Perl's builtin time() function for
returning the number of seconds since the epoch (whatever it is
for the system), see "time" in perlfunc.
"times" The times() function returns elapsed realtime since some point
in the past (such as system startup), user and system times for
this process, and user and system times used by child processes.
All times are returned in clock ticks.
($realtime, $user, $system, $cuser, $csystem)
= POSIX::times();
Note: Perl's builtin times() function returns four values,
measured in seconds.
"tmpfile"
Not implemented. Use method IO::File::new_tmpfile() instead, or
see File::Temp.
"tmpnam"
For security reasons, which are probably detailed in your
system's documentation for the C library tmpnam() function, this
interface is no longer available since Perl v5.26; instead use
File::Temp.
"tolower"
This function has been removed as of Perl v5.26. This is
identical to the C function, except that it can apply to a
single character or to a whole string, and currently operates as
if the locale always is "C". Consider using the lc() function,
see "lc" in perlfunc, see "lc" in perlfunc, or the equivalent
"\L" operator inside doublequotish strings.
"toupper"
This function has been removed as of Perl v5.26. This is
similar to the C function, except that it can apply to a single
character or to a whole string, and currently operates as if the
locale always is "C". Consider using the uc() function, see
"uc" in perlfunc, or the equivalent "\U" operator inside
doublequotish strings.
"trunc" Returns the integer toward zero from the argument [C99]. Added
in Perl v5.22.
See also "ceil", "floor", and "round".
"ttyname"
This is identical to the C function ttyname() for returning the
name of the current terminal.
"tzname"
Retrieves the time conversion information from the "tzname"
variable.
POSIX::tzset();
($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 -- except that
POSIX::umask() must be provided with an explicit value (rather
than relying on an implicit $_):
$current = umask(); # good
$now = POSIX::umask($current); # good
$now = POSIX::umask(); # throws exception
See "umask" in perlfunc.
"uname" Get name of current operating system.
($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 "unlink" in perlfunc.
"utime" This is identical to Perl's builtin utime() function for
changing the time stamps of files and directories, see "utime"
in perlfunc.
"vfprintf"
Not implemented. vfprintf() is C-specific, see "printf" in
perlfunc instead.
"vprintf"
Not implemented. vprintf() is C-specific, see "printf" in
perlfunc instead.
"vsprintf"
Not implemented. vsprintf() is C-specific, see "sprintf" in
perlfunc instead.
"wait" This is identical to Perl's builtin wait() function, see "wait"
in perlfunc.
"waitpid"
Wait for a child process to change state. This is identical to
Perl's builtin waitpid() function, see "waitpid" in perlfunc.
$pid = POSIX::waitpid( -1, POSIX::WNOHANG );
print "status = ", ($? / 256), "\n";
See "mblen".
"wctomb"
This is the same as the C function wctomb() on unthreaded perls.
On threaded perls, it transparently (almost) substitutes the
more thread-safe "wcrtomb"(3), if available, instead of
"wctomb".
Core Perl does not have any support for wide and multibyte
locales, except Unicode UTF-8 locales. This function, in
conjunction with "mblen" and "mbtowc" may be used to roll your
own decoding/encoding of other types of multi-byte locales.
Use "undef" as the first parameter to this function to get the
effect of passing NULL as the first parameter to "wctomb". This
ignores the second parameter, and resets any shift state to its
initial value. The return value is undefined if "wcrtomb" was
substituted, so you should never rely on it.
When the first parameter is a scalar, the code point contained
in the scalar second parameter is converted into a multi-byte
string and stored into the first parameter scalar. This is
based on the locale that currently underlies the program,
regardless of whether or not the function is called from Perl
code that is within the scope of "use locale". The return value
is the number of bytes stored; or negative if the code point
isn't representable in the current locale. Perl makes no
attempt at hiding from your code any differences in the "errno"
setting between "wctomb" and "wcrtomb". It does set "errno" to
0 before calling them.
"write" Write to a file. This uses file descriptors such as those
obtained by calling "POSIX::open".
$fd = POSIX::open( "foo", &POSIX::O_WRONLY );
$buf = "hello";
$bytes = POSIX::write( $fd, $buf, 5 );
Returns "undef" on failure.
See also "syswrite" in perlfunc.
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 );
Throws an error if any of the signals supplied cannot be added
to the set.
"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"
RESOURCE CONSTANTS
Imported with the ":sys_resource_h" tag.
Constants
Added in Perl v5.28:
"PRIO_PROCESS" "PRIO_PGRP" "PRIO_USER"
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"
Added in Perl v5.22:
"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"
Added in Perl v5.24:
"ILL_ILLOPC" "ILL_ILLOPN" "ILL_ILLADR" "ILL_ILLTRP" "ILL_PRVOPC"
"ILL_PRVREG" "ILL_COPROC" "ILL_BADSTK" "FPE_INTDIV" "FPE_INTOVF"
"FPE_FLTDIV" "FPE_FLTOVF" "FPE_FLTUND" "FPE_FLTRES" "FPE_FLTINV"
"FPE_FLTSUB" "SEGV_MAPERR" "SEGV_ACCERR" "BUS_ADRALN"
"BUS_ADRERR" "BUS_OBJERR" "TRAP_BRKPT" "TRAP_TRACE" "CLD_EXITED"
"CLD_KILLED" "CLD_DUMPED" "CLD_TRAPPED" "CLD_STOPPED"
"CLD_CONTINUED" "POLL_IN" "POLL_OUT" "POLL_MSG" "POLL_ERR"
"POLL_PRI" "POLL_HUP" "SI_USER" "SI_QUEUE" "SI_TIMER"
"SI_ASYNCIO" "SI_MESGQ"
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_ISLNK" "S_ISREG"
"S_ISSOCK"
STDLIB
Constants
"EXIT_FAILURE" "EXIT_SUCCESS" "MB_CUR_MAX" "RAND_MAX"
STDIO
Constants
"BUFSIZ" "EOF" "FILENAME_MAX" "L_ctermid" "L_cuserid" "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)
WINSOCK
(Windows only.)
Constants
Added in Perl v5.24:
"WSAEINTR" "WSAEBADF" "WSAEACCES" "WSAEFAULT" "WSAEINVAL"
"WSAEMFILE" "WSAEWOULDBLOCK" "WSAEINPROGRESS" "WSAEALREADY"
"WSAENOTSOCK" "WSAEDESTADDRREQ" "WSAEMSGSIZE" "WSAEPROTOTYPE"
"WSAENOPROTOOPT" "WSAEPROTONOSUPPORT" "WSAESOCKTNOSUPPORT"
"WSAEOPNOTSUPP" "WSAEPFNOSUPPORT" "WSAEAFNOSUPPORT"
"WSAEADDRINUSE" "WSAEADDRNOTAVAIL" "WSAENETDOWN"
"WSAENETUNREACH" "WSAENETRESET" "WSAECONNABORTED"
"WSAECONNRESET" "WSAENOBUFS" "WSAEISCONN" "WSAENOTCONN"
"WSAESHUTDOWN" "WSAETOOMANYREFS" "WSAETIMEDOUT"
"WSAECONNREFUSED" "WSAELOOP" "WSAENAMETOOLONG" "WSAEHOSTDOWN"
"WSAEHOSTUNREACH" "WSAENOTEMPTY" "WSAEPROCLIM" "WSAEUSERS"
"WSAEDQUOT" "WSAESTALE" "WSAEREMOTE" "WSAEDISCON" "WSAENOMORE"
"WSAECANCELLED" "WSAEINVALIDPROCTABLE" "WSAEINVALIDPROVIDER"
"WSAEPROVIDERFAILEDINIT" "WSAEREFUSED"
perl v5.40.1 2026-08-30 POSIX(3perl)
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