POSIX - Perl interface to IEEE Std 1003.1
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.
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.
_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 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 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 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 chdir.
chmod
This is identical to Perl's builtin chmod() function, allowing
one to change file and directory permissions, see chmod.
chown
This is identical to Perl's builtin chown() function, allowing one
to change file and directory owners and groups, see chown.
clearerr
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.
closedir
This is identical to Perl's builtin closedir() function for closing
a directory handle, see closedir.
cos
This is identical to Perl's builtin cos() function, for returning
the cosine of its numerical argument, see cos.
See also Math::Trig.
cosh
This is identical to the C function cosh()
, for returning
the hyperbolic cosine of its numeric argument.  See also Math::Trig.
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 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 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 $ERRNO in perlvar.
execl
Not implemented.  execl()
 is C-specific, see exec.
execle
Not implemented.  execle()
 is C-specific, see exec.
execlp
Not implemented.  execlp()
 is C-specific, see exec.
execv
Not implemented.  execv()
 is C-specific, see exec.
execve
Not implemented.  execve()
 is C-specific, see exec.
execvp
Not implemented.  execvp()
 is C-specific, see exec.
exit
This is identical to Perl's builtin exit() function for exiting the
program, see exit.
exp
This is identical to Perl's builtin exp() function for
returning the exponent (e-based) of the numerical argument,
see exp.
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 abs.
fclose
Not implemented.  Use method IO::Handle::close()
 instead, or see close.
fcntl
This is identical to Perl's builtin fcntl() function,
see fcntl.
fdopen
Not implemented.  Use method IO::Handle::new_from_fd()
 instead, or see open.
feof
Not implemented.  Use method IO::Handle::eof()
 instead, or see eof.
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.
fgetpos
Not implemented.  Use method IO::Seekable::getpos()
 instead, or see seek.
fgets
Not implemented.  Use method IO::Handle::gets()
 instead.  Similar to <>, also known
as readline.
fileno
Not implemented.  Use method IO::Handle::fileno()
 instead, or see fileno.
floor
This is identical to the C function floor()
, returning the largest
integer value less than or equal to the numerical argument.
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 open.
fork
This is identical to Perl's builtin fork() function
for duplicating the current process, see fork
and perlfork if you are in Windows.
fpathconf
Retrieves the value of a configurable limit on a file or directory.  This
uses file descriptors such as those obtained by calling POSIX::open
.
The following will determine the maximum length of the longest allowable pathname on the filesystem which holds /var/foo.
- $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
- $path_max = POSIX::fpathconf($fd, &POSIX::_PC_PATH_MAX);
Returns undef on failure.
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 printf instead.
fputc
Not implemented.  fputc()
 is C-specific, see print instead.
fputs
Not implemented.  fputs()
 is C-specific, see print instead.
fread
Not implemented.  fread()
 is C-specific, see read instead.
free
Not implemented.  free()
 is C-specific.  Perl does memory management transparently.
freopen
Not implemented.  freopen()
 is C-specific, see open instead.
frexp
Return the mantissa and exponent of a floating-point number.
- ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
fscanf
Not implemented.  fscanf()
 is C-specific, use <> and regular expressions instead.
fseek
Not implemented.  Use method IO::Seekable::seek()
 instead, or see seek.
fsetpos
Not implemented.  Use method IO::Seekable::setpos()
 instead, or seek seek.
fstat
Get file status.  This uses file descriptors such as those obtained by
calling POSIX::open
.  The data returned is identical to the data from
Perl's builtin stat function.
- $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
- @stats = POSIX::fstat( $fd );
fsync
Not implemented.  Use method IO::Handle::sync()
 instead.
ftell
Not implemented.  Use method IO::Seekable::tell()
 instead, or see tell.
fwrite
Not implemented.  fwrite()
 is C-specific, see print instead.
getc
This is identical to Perl's builtin getc() function,
see getc.
getchar
Returns one character from STDIN.  Identical to Perl's getc(),
see getc.
getcwd
Returns the name of the current working directory. See also Cwd.
getegid
Returns the effective group identifier.  Similar to Perl' s builtin
variable $(
, see $EGID in perlvar.
getenv
Returns the value of the specified environment variable.
The same information is available through the %ENV
 array.
geteuid
Returns the effective user identifier.  Identical to Perl's builtin $>
variable, see $EUID in perlvar.
getgid
Returns the user's real group identifier.  Similar to Perl's builtin
variable $)
, see $GID in perlvar.
getgrgid
This is identical to Perl's builtin getgrgid() function for
returning group entries by group identifiers, see
getgrgid.
getgrnam
This is identical to Perl's builtin getgrnam() function for
returning group entries by group names, see getgrnam.
getgroups
Returns the ids of the user's supplementary groups.  Similar to Perl's
builtin variable $)
, see $GID in perlvar.
getlogin
This is identical to Perl's builtin getlogin() function for
returning the user name associated with the current session, see
getlogin.
getpayload
- use POSIX ':nan_payload';
- getpayload($var)
Returns the NaN
 payload.
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.
getpid
Returns the process identifier.  Identical to Perl's builtin
variable $$
, see $PID in perlvar.
getppid
This is identical to Perl's builtin getppid() function for
returning the process identifier of the parent process of the current
process , see getppid.
getpwnam
This is identical to Perl's builtin getpwnam() function for
returning user entries by user names, see getpwnam.
getpwuid
This is identical to Perl's builtin getpwuid() function for
returning user entries by user identifiers, see getpwuid.
gets
Returns one line from STDIN
, similar to <>, also known
as the readline() function, see readline.
NOTE: if you have C programs that still use gets()
, be very
afraid.  The gets()
 function is a source of endless grief because
it has no buffer overrun checks.  It should never be used.  The
fgets()
 function should be preferred instead.
getuid
Returns the user's identifier.  Identical to Perl's builtin $<
 variable,
see $UID in perlvar.
gmtime
This is identical to Perl's builtin gmtime() function for
converting seconds since the epoch to a date in Greenwich Mean Time,
see gmtime.
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:
See also isinf, and fpclassify.
isalnum
This function has been removed as of 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 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.
iscntrl
This function has been removed as of 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 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].
See also isinf, isnan, and fpclassify.
isgraph
This function has been removed as of 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].
isinf
Returns true if the argument is an infinity (positive or negative) [C99].
See also Inf, isnan, isfinite, and fpclassify.
islower
This function has been removed as of 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].
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
This function has been removed as of 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 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.
Note the API instability warning in setpayload.
See nan for more discussion about NaN
.
isspace
This function has been removed as of 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 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 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.
labs
Not implemented.  (For returning absolute values of long integers.)
labs()
 is C-specific, see abs instead.
lchown
This is identical to the C function, except the order of arguments is
consistent with Perl's builtin chown() with the added restriction
of only one path, not 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 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 localtime.
log
This is identical to Perl's builtin log() function,
returning the natural (e-based) logarithm of the numerical argument,
see log.
log10
This is identical to the C function log10()
,
returning the 10-base logarithm of the numerical argument.
You can also use
or
- sub log10 { log($_[0]) / 2.30258509299405 }
or
- sub log10 { log($_[0]) * 0.434294481903252 }
longjmp
Not implemented.  longjmp()
 is C-specific: use die instead.
lseek
Move the file's read/write position.  This uses file descriptors such as
those obtained by calling POSIX::open
.
- $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
- $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );
Returns undef on failure.
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].
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 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 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 substr.
memmove
Not implemented.  memmove()
 is C-specific, use =
, see perlop, or see 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 mkdir.
mkfifo
This is similar to the C function mkfifo()
 for creating
FIFO special files.
- if (mkfifo($path, $mode)) { ....
Returns undef on failure.  The $mode
 is similar to the
mode of mkdir(), see mkdir, though for mkfifo
you must specify the $mode
.
mktime
Convert date/time info to a calendar time.
Synopsis:
- mktime(sec, min, hour, mday, mon, year, wday = 0,
- yday = 0, isdst = -1)
The month (mon
), weekday (wday
), and yearday (yday
) begin at zero,
i.e., January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1.  The
year (year
) is given in years since 1900; i.e., the year 1995 is 95; the
year 2001 is 101.  Consult your system's mktime()
 manpage for details
about these and the other arguments.
Calendar time for December 12, 1995, at 10:30 am.
- $time_t = POSIX::mktime( 0, 30, 10, 12, 11, 95 );
- print "Date = ", POSIX::ctime($time_t);
Returns undef on failure.
modf
Return the integral and fractional parts of a floating-point number.
- ($fractional, $integral) = POSIX::modf( 3.14 );
See also round.
NaN
The not-a-number as a constant:
See also nan, /isnan
, and fpclassify.
nan
- my $nan = nan();
Returns NaN
, not-a-number [C99].
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].
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 pack instead.
open
Open a file for reading for writing.  This returns file descriptors, not
Perl filehandles.  Use POSIX::close
 to close the file.
Open a file read-only with mode 0666.
- $fd = POSIX::open( "foo" );
Open a file for read and write.
- $fd = POSIX::open( "foo", &POSIX::O_RDWR );
Open a file for write, with truncation.
- $fd = POSIX::open(
- "foo", &POSIX::O_WRONLY | &POSIX::O_TRUNC
- );
Create a new file with mode 0640. Set up the file for writing.
- $fd = POSIX::open(
- "foo", &POSIX::O_CREAT | &POSIX::O_WRONLY, 0640
- );
Returns undef on failure.
See also sysopen.
opendir
Open a directory for reading.
- $dir = POSIX::opendir( "/var" );
- @files = POSIX::readdir( $dir );
- POSIX::closedir( $dir );
Returns undef on failure.
pathconf
Retrieves the value of a configurable limit on a file or directory.
The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds /var.
- $path_max = POSIX::pathconf( "/var",
- &POSIX::_PC_PATH_MAX );
Returns undef on failure.
pause
This is similar to the C function pause()
, which suspends
the execution of the current process until a signal is received.
Returns undef on failure.
perror
This is identical to the C function perror()
, which outputs to the
standard error stream the specified message followed by ": "
 and the
current error string.  Use the warn() function and the $!
variable instead, see warn and $ERRNO in perlvar.
pipe
Create an interprocess channel.  This returns file descriptors like those
returned by POSIX::open
.
- my ($read, $write) = POSIX::pipe();
- POSIX::write( $write, "hello", 5 );
- POSIX::read( $read, $buf, 5 );
See also pipe.
pow
Computes $x
 raised to the power $exponent
.
- $ret = POSIX::pow( $x, $exponent );
You can also use the **
 operator, see perlop.
printf
Formats and prints the specified arguments to STDOUT
.
See also printf.
putc
Not implemented.  putc()
 is C-specific, see print instead.
putchar
Not implemented.  putchar()
 is C-specific, see print instead.
puts
Not implemented.  puts()
 is C-specific, see print instead.
qsort
Not implemented.  qsort()
 is C-specific, see sort instead.
raise
Sends the specified signal to the current process.
See also kill and the $$
 in $PID in perlvar.
rand
read
Read from a file.  This uses file descriptors such as those obtained by
calling POSIX::open
.  If the buffer $buf
 is not large enough for the
read then Perl will extend it to make room for the request.
- $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
- $bytes = POSIX::read( $fd, $buf, 3 );
Returns undef on failure.
See also sysread.
readdir
This is identical to Perl's builtin readdir() function
for reading directory entries, see readdir.
realloc
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 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 rename.
rewind
Seeks to the beginning of the file.
rewinddir
This is identical to Perl's builtin rewinddir() function for
rewinding directory entry streams, see rewinddir.
rint
Identical to lrint.
rmdir
This is identical to Perl's builtin rmdir() function
for removing (empty) directories, see rmdir.
round
Returns the integer (but still as floating point) nearest to the argument [C99].
scalbn
Returns x * 2**y
 [C99].
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.
setlocale
WARNING! 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.
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.)
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, $payload);
Sets the NaN
 payload of var.
NOTE: the NaN payload APIs are based on the latest (as of June 2015) proposed ISO C interfaces, but they are not yet a standard. Things may change.
See nan for more discussion about NaN
.
See also setpayloadsig, isnan, getpayload, and issignaling.
setpayloadsig
- use POSIX ':nan_payload';
- setpayloadsig($var, $payload);
Like setpayload but also makes the NaN signaling.
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.
The following are also defined by POSIX/SUSv3, but unfortunately not very widely implemented:
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 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 eval.
sigsuspend
Install a signal mask and suspend process until signal arrives.  This uses
POSIX::SigSet
 objects for the signal_mask
 argument.  Consult your
system's sigsuspend
 manpage for details.
Synopsis:
- sigsuspend(signal_mask)
Returns undef on failure.
sin
This is identical to Perl's builtin sin() function
for returning the sine of the numerical argument,
see sin.  See also Math::Trig.
sinh
This is identical to the C function sinh()
for returning the hyperbolic sine of the numerical argument.
See also Math::Trig.
sleep
This is functionally identical to Perl's builtin sleep() function
for suspending the execution of the current for process for certain
number of seconds, see sleep.  There is one significant
difference, however: POSIX::sleep()
 returns the number of
unslept seconds, while the CORE::sleep()
 returns the
number of slept seconds.
sprintf
This is similar to Perl's builtin sprintf() function
for returning a string that has the arguments formatted as requested,
see sprintf.
sqrt
This is identical to Perl's builtin sqrt() function.
for returning the square root of the numerical argument,
see sqrt.
srand
Give a seed the pseudorandom number generator, see srand.
sscanf
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 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.
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. 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 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 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 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 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.
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.
sysconf
Retrieves values of system configurable variables.
The following will get the machine's clock speed.
- $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
Returns undef on failure.
system
This is identical to Perl's builtin system() function, see
system.
tan
This is identical to the C function tan()
, returning the
tangent of the numerical argument.  See also Math::Trig.
tanh
This is identical to the C function tanh()
, returning the
hyperbolic tangent of the numerical argument.   See also Math::Trig.
tcdrain
This is similar to the C function tcdrain()
 for draining
the output queue of its argument stream.
Returns undef on failure.
tcflow
This is similar to the C function tcflow()
 for controlling
the flow of its argument stream.
Returns undef on failure.
tcflush
This is similar to the C function tcflush()
 for flushing
the I/O buffers of its argument stream.
Returns undef on failure.
tcgetpgrp
This is identical to the C function tcgetpgrp()
 for returning the
process group identifier of the foreground process group of the controlling
terminal.
tcsendbreak
This is similar to the C function tcsendbreak()
 for sending
a break on its argument stream.
Returns undef on failure.
tcsetpgrp
This is similar to the C function tcsetpgrp()
 for setting the
process group identifier of the foreground process group of the controlling
terminal.
Returns undef on failure.
tgamma
The Gamma function [C99].
See also lgamma.
time
This is identical to Perl's builtin time() function
for returning the number of seconds since the epoch
(whatever it is for the system), see time.
times
The times() function returns elapsed realtime since some point in the past
(such as system startup), user and system times for this process, and user
and system times used by child processes.  All times are returned in clock
ticks.
- ($realtime, $user, $system, $cuser, $csystem)
- = POSIX::times();
Note: Perl's builtin times() function returns four values, measured in
seconds.
tmpfile
Not implemented.  Use method IO::File::new_tmpfile()
 instead, or see File::Temp.
tmpnam
For security reasons, which are probably detailed in your system's
documentation for the C library tmpnam()
 function, this interface
is no longer available; instead use File::Temp.
tolower
This is identical to the C function, except that it can apply to a single
character or to a whole string, and currently operates as if the locale
always is "C".  Consider using the lc() function, see lc,
see lc, or the equivalent \L
 operator inside doublequotish
strings.
toupper
This is similar to the C function, except that it can apply to a single
character or to a whole string, and currently operates as if the locale
always is "C".  Consider using the uc() function, see uc,
or the equivalent \U
 operator inside doublequotish strings.
trunc
Returns the integer toward zero from the argument [C99].
ttyname
This is identical to the C function ttyname()
 for returning the
name of the current terminal.
tzname
Retrieves the time conversion information from the tzname
 variable.
- POSIX::tzset();
- ($std, $dst) = POSIX::tzname();
tzset
This is identical to the C function tzset()
 for setting
the current timezone based on the environment variable TZ
,
to be used by ctime()
, localtime(), mktime()
, and strftime()
functions.
umask
This is identical to Perl's builtin umask() function
for setting (and querying) the file creation permission mask,
see umask.
uname
Get name of current operating system.
- ($sysname, $nodename, $release, $version, $machine)
- = POSIX::uname();
Note that the actual meanings of the various fields are not
that well standardized, do not expect any great portability.
The $sysname
 might be the name of the operating system,
the $nodename
 might be the name of the host, the $release
might be the (major) release number of the operating system,
the $version
 might be the (minor) release number of the
operating system, and the $machine
 might be a hardware identifier.
Maybe.
ungetc
Not implemented.  Use method IO::Handle::ungetc()
 instead.
unlink
This is identical to Perl's builtin unlink() function
for removing files, see unlink.
utime
This is identical to Perl's builtin utime() function
for changing the time stamps of files and directories,
see utime.
vfprintf
Not implemented.  vfprintf()
 is C-specific, see printf instead.
vprintf
Not implemented.  vprintf()
 is C-specific, see printf instead.
vsprintf
Not implemented.  vsprintf()
 is C-specific, see sprintf instead.
wait
This is identical to Perl's builtin wait() function,
see wait.
waitpid
Wait for a child process to change state.  This is identical to Perl's
builtin waitpid() function, see waitpid.
- $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
- print "status = ", ($? / 256), "\n";
wcstombs
This is identical to the C function wcstombs()
.
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 syswrite.
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:
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.
B38400
 B75
 B200
 B134
 B300
 B1800
 B150
 B0
 B19200
 B1200
 B9600
 B600
 B4800
 B50
 B2400
 B110
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
_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_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
_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
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
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
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
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
LC_ALL
 LC_COLLATE
 LC_CTYPE
 LC_MONETARY
 LC_NUMERIC
 LC_TIME
 LC_MESSAGES
on systems that support them.
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.
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
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
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
S_ISBLK
 S_ISCHR
 S_ISDIR
 S_ISFIFO
 S_ISREG
WNOHANG
 WUNTRACED
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)
(Windows only.)
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