POSIX(3pm) Perl Programmers Reference Guide POSIX(3pm)
NAME
POSIX - Perl interface to IEEE Std 1003.1
SYNOPSIS
use POSIX ();
use POSIX qw(setsid);
use POSIX qw(:errno_h :fcntl_h);
printf "EINTR is %d\n", EINTR;
$sess_id = POSIX::setsid();
$fd = POSIX::open($path, O_CREAT|O_EXCL|O_WRONLY, 0644);
# note: that's a filedescriptor, *NOT* a filehandle
DESCRIPTION
The POSIX module permits you to access all (or nearly all) the standard
POSIX 1003.1 identifiers. Many of these identifiers have been given
Perl-ish interfaces.
This document gives a condensed list of the features available in the
POSIX module. Consult your operating system's manpages for general
information on most features. Consult perlfunc for functions which are
noted as being identical to Perl's builtin functions.
The first section describes POSIX functions from the 1003.1
specification. The second section describes some classes for signal
objects, TTY objects, and other miscellaneous objects. The remaining
sections list various constants and macros in an organization which
roughly follows IEEE Std 1003.1b-1993.
CAVEATS
Everything is exported by default (with a handful of exceptions). This
is an unfortunate backwards compatibility feature and its use is
strongly discouraged. You should either prevent the exporting (by
saying "use POSIX ();", as usual) and then use fully qualified names
(e.g. "POSIX::SEEK_END"), or give an explicit import list. If you do
neither and opt for the default (as in "use POSIX;"), you will import
hundreds and hundreds of symbols into your namespace.
A few functions are not implemented because they are C specific. If
you attempt to call these, they will print a message telling you that
they aren't implemented, and suggest using the Perl equivalent, should
one exist. For example, trying to access the "setjmp()" call will
elicit the message ""setjmp() is C-specific: use eval {} instead"".
Furthermore, some evil vendors will claim 1003.1 compliance, but in
fact are not so: they will not pass the PCTS (POSIX Compliance Test
Suites). For example, one vendor may not define "EDEADLK", or the
semantics of the errno values set by open(2) might not be quite right.
Perl does not attempt to verify POSIX compliance. That means you can
currently successfully say "use POSIX", and then later in your program
you find that your vendor has been lax and there's no usable "ICANON"
macro after all. This could be construed to be a bug.
FUNCTIONS
"_exit" This is identical to the C function "_exit()". It exits the
program immediately which means among other things buffered I/O
is not flushed.
Note that when using threads and in Linux this is not a good
way to exit a thread because in Linux processes and threads are
kind of the same thing (Note: while this is the situation in
early 2003 there are projects under way to have threads with
more POSIXly semantics in Linux). If you want not to return
from a thread, detach the thread.
"abort" This is identical to the C function "abort()". It terminates
the process with a "SIGABRT" signal unless caught by a signal
handler or if the handler does not return normally (it e.g.
does a "longjmp").
"abs" This is identical to Perl's builtin "abs()" function, returning
the absolute value of its numerical argument.
"access"
Determines the accessibility of a file.
if( POSIX::access( "/", &POSIX::R_OK ) ){
print "have read permission\n";
}
Returns "undef" on failure. Note: do not use "access()" for
security purposes. Between the "access()" call and the
operation you are preparing for the permissions might change: a
classic race condition.
"acos" This is identical to the C function "acos()", returning the
arcus cosine of its numerical argument. See also Math::Trig.
"acosh" This is identical to the C function "acosh()", returning the
hyperbolic arcus cosine of its numerical argument [C99]. See
also Math::Trig.
"alarm" This is identical to Perl's builtin "alarm()" function, either
for arming or disarming the "SIGARLM" timer.
"asctime"
This is identical to the C function "asctime()". It returns a
string of the form
"Fri Jun 2 18:22:13 2000\n\0"
and it is called thusly
$asctime = asctime($sec, $min, $hour, $mday, $mon,
$year, $wday, $yday, $isdst);
The $mon is zero-based: January equals 0. The $year is
1900-based: 2001 equals 101. $wday and $yday default to zero
(and are usually ignored anyway), and $isdst defaults to -1.
"asin" This is identical to the C function "asin()", returning the
arcus sine of its numerical argument. See also Math::Trig.
"asinh" This is identical to the C function "asinh()", returning the
hyperbolic arcus sine of its numerical argument [C99]. See
also Math::Trig.
"assert"
Unimplemented, but you can use "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.
"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].
"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.
"chmod" This is identical to Perl's builtin "chmod()" function,
allowing one to change file and directory permissions, see
"chmod" in perlfunc.
"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, 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].
$x_with_sign_of_y = POSIX::copysign($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"
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" 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].
"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" 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, see
"exp" in perlfunc.
"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" in perlfunc.
"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].
"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" 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.
"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.
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].
"ilogb" Integer binary logarithm [C99]
For example "ilogb(20)" is 4, as an integer.
See also "logb".
"Inf" The infinity as a constant:
use POSIX qw(Inf);
my $pos_inf = +Inf; # Or just Inf.
my $neg_inf = -Inf;
See also "isinf", and "fpclassify".
"isalnum"
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"
in perlfunc.
"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" 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].
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" in perlfunc.
"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" in
perlfunc.
"log" This is identical to Perl's builtin "log()" function, returning
the natural (e-based) logarithm of the numerical argument, 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].
For the rounding mode, see "fegetround".
"lround"
Like "round", but as integer, as opposed to floating point
[C99].
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 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" 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].
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" 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]
my $remainder = POSIX::remainder($x, $y)
See also "remquo".
"remove"
This is identical to Perl's builtin "unlink()" function for
removing files, see "unlink" in perlfunc.
"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" 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].
See also "ceil", "floor", "lround", "modf", and "trunc".
"scalbn"
Returns "x * 2**y" [C99].
See also "frexp" and "ldexp".
"scanf" Not implemented. "scanf()" is C-specific, use <> and regular
expressions instead, see perlre.
"setgid"
Sets the real group identifier and the effective group
identifier for this process. Similar to assigning a value to
the Perl's builtin $) variable, see "$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! 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:
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].
"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 the numerical argument, 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, 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.
"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" 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_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" 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 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.
$clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
Returns "undef" on failure.
"system"
This is identical to Perl's builtin "system()" function, see
"system" in perlfunc.
"tan" This is identical to the C function "tan()", returning the
tangent of the numerical argument. See also Math::Trig.
"tanh" This is identical to the C function "tanh()", returning the
hyperbolic tangent of the numerical argument. See also
Math::Trig.
"tcdrain"
This is similar to the C function "tcdrain()" for draining the
output queue of its argument stream.
Returns "undef" on failure.
"tcflow"
This is similar to the C function "tcflow()" for controlling
the flow of its argument stream.
Returns "undef" on failure.
"tcflush"
This is similar to the C function "tcflush()" for flushing the
I/O buffers of its argument stream.
Returns "undef" on failure.
"tcgetpgrp"
This is identical to the C function "tcgetpgrp()" for returning
the process group identifier of the foreground process group of
the controlling terminal.
"tcsendbreak"
This is similar to the C function "tcsendbreak()" for sending a
break on its argument stream.
Returns "undef" on failure.
"tcsetpgrp"
This is similar to the C function "tcsetpgrp()" for setting the
process group identifier of the foreground process group of the
controlling terminal.
Returns "undef" on failure.
"tgamma"
The Gamma function [C99].
See also "lgamma".
"time" This is identical to Perl's builtin "time()" function for
returning the number of seconds since the epoch (whatever it is
for the system), see "time" in perlfunc.
"times" The "times()" function returns elapsed realtime since some
point in the past (such as system startup), user and system
times for this process, and user and system times used by child
processes. All times are returned in clock ticks.
($realtime, $user, $system, $cuser, $csystem)
= POSIX::times();
Note: Perl's builtin "times()" function returns four values,
measured in seconds.
"tmpfile"
Not implemented. Use method "IO::File::new_tmpfile()" instead,
or see File::Temp.
"tmpnam"
For security reasons, which are probably detailed in your
system's documentation for the C library "tmpnam()" function,
this interface is no longer available; instead use File::Temp.
"tolower"
This is identical to the C function, except that it can apply
to a single character or to a whole string, and currently
operates as if the locale always is "C". Consider using the
"lc()" function, see "lc" in perlfunc, see "lc" in perlfunc, or
the equivalent "\L" operator inside doublequotish strings.
"toupper"
This is similar to the C function, except that it can apply to
a single character or to a whole string, and currently operates
as if the locale always is "C". Consider using the "uc()"
function, see "uc" in perlfunc, or the equivalent "\U" operator
inside doublequotish strings.
"trunc" Returns the integer toward zero from the argument [C99].
See also "ceil", "floor", and "round".
"ttyname"
This is identical to the C function "ttyname()" for returning
the name of the current terminal.
"tzname"
Retrieves the time conversion information from the "tzname"
variable.
POSIX::tzset();
($std, $dst) = POSIX::tzname();
"tzset" This is identical to the C function "tzset()" for setting the
current timezone based on the environment variable "TZ", to be
used by "ctime()", "localtime()", "mktime()", and "strftime()"
functions.
"umask" This is identical to Perl's builtin "umask()" function for
setting (and querying) the file creation permission mask, see
"umask" in perlfunc.
"uname" Get name of current operating system.
($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";
"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" 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 );
"addset"
Add a signal to a SigSet object.
$sigset->addset( &POSIX::SIGUSR2 );
Returns "undef" on failure.
"delset"
Remove a signal from the SigSet object.
$sigset->delset( &POSIX::SIGUSR2 );
Returns "undef" on failure.
"emptyset"
Initialize the SigSet object to be empty.
$sigset->emptyset();
Returns "undef" on failure.
"fillset"
Initialize the SigSet object to include all signals.
$sigset->fillset();
Returns "undef" on failure.
"ismember"
Tests the SigSet object to see if it contains a specific
signal.
if( $sigset->ismember( &POSIX::SIGUSR1 ) ){
print "contains SIGUSR1\n";
}
"POSIX::Termios"
"new" Create a new Termios object. This object will be destroyed
automatically when it is no longer needed. A Termios object
corresponds to the "termios" C struct. "new()" mallocs a new
one, "getattr()" fills it from a file descriptor, and
"setattr()" sets a file descriptor's parameters to match
Termios' contents.
$termios = POSIX::Termios->new;
"getattr"
Get terminal control attributes.
Obtain the attributes for "stdin".
$termios->getattr( 0 ) # Recommended for clarity.
$termios->getattr()
Obtain the attributes for stdout.
$termios->getattr( 1 )
Returns "undef" on failure.
"getcc" Retrieve a value from the "c_cc" field of a "termios" object.
The "c_cc" field is an array so an index must be specified.
$c_cc[1] = $termios->getcc(1);
"getcflag"
Retrieve the "c_cflag" field of a "termios" object.
$c_cflag = $termios->getcflag;
"getiflag"
Retrieve the "c_iflag" field of a "termios" object.
$c_iflag = $termios->getiflag;
"getispeed"
Retrieve the input baud rate.
$ispeed = $termios->getispeed;
"getlflag"
Retrieve the "c_lflag" field of a "termios" object.
$c_lflag = $termios->getlflag;
"getoflag"
Retrieve the "c_oflag" field of a "termios" object.
$c_oflag = $termios->getoflag;
"getospeed"
Retrieve the output baud rate.
$ospeed = $termios->getospeed;
"setattr"
Set terminal control attributes.
Set attributes immediately for stdout.
$termios->setattr( 1, &POSIX::TCSANOW );
Returns "undef" on failure.
"setcc" Set a value in the "c_cc" field of a "termios" object. The
"c_cc" field is an array so an index must be specified.
$termios->setcc( &POSIX::VEOF, 1 );
"setcflag"
Set the "c_cflag" field of a "termios" object.
$termios->setcflag( $c_cflag | &POSIX::CLOCAL );
"setiflag"
Set the "c_iflag" field of a "termios" object.
$termios->setiflag( $c_iflag | &POSIX::BRKINT );
"setispeed"
Set the input baud rate.
$termios->setispeed( &POSIX::B9600 );
Returns "undef" on failure.
"setlflag"
Set the "c_lflag" field of a "termios" object.
$termios->setlflag( $c_lflag | &POSIX::ECHO );
"setoflag"
Set the "c_oflag" field of a "termios" object.
$termios->setoflag( $c_oflag | &POSIX::OPOST );
"setospeed"
Set the output baud rate.
$termios->setospeed( &POSIX::B9600 );
Returns "undef" on failure.
Baud rate values
"B38400" "B75" "B200" "B134" "B300" "B1800" "B150" "B0"
"B19200" "B1200" "B9600" "B600" "B4800" "B50" "B2400" "B110"
Terminal interface values
"TCSADRAIN" "TCSANOW" "TCOON" "TCIOFLUSH" "TCOFLUSH" "TCION"
"TCIFLUSH" "TCSAFLUSH" "TCIOFF" "TCOOFF"
"c_cc" field values
"VEOF" "VEOL" "VERASE" "VINTR" "VKILL" "VQUIT" "VSUSP" "VSTART"
"VSTOP" "VMIN" "VTIME" "NCCS"
"c_cflag" field values
"CLOCAL" "CREAD" "CSIZE" "CS5" "CS6" "CS7" "CS8" "CSTOPB"
"HUPCL" "PARENB" "PARODD"
"c_iflag" field values
"BRKINT" "ICRNL" "IGNBRK" "IGNCR" "IGNPAR" "INLCR" "INPCK"
"ISTRIP" "IXOFF" "IXON" "PARMRK"
"c_lflag" field values
"ECHO" "ECHOE" "ECHOK" "ECHONL" "ICANON" "IEXTEN" "ISIG"
"NOFLSH" "TOSTOP"
"c_oflag" field values
"OPOST"
PATHNAME CONSTANTS
Constants
"_PC_CHOWN_RESTRICTED" "_PC_LINK_MAX" "_PC_MAX_CANON"
"_PC_MAX_INPUT" "_PC_NAME_MAX" "_PC_NO_TRUNC" "_PC_PATH_MAX"
"_PC_PIPE_BUF" "_PC_VDISABLE"
POSIX CONSTANTS
Constants
"_POSIX_ARG_MAX" "_POSIX_CHILD_MAX" "_POSIX_CHOWN_RESTRICTED"
"_POSIX_JOB_CONTROL" "_POSIX_LINK_MAX" "_POSIX_MAX_CANON"
"_POSIX_MAX_INPUT" "_POSIX_NAME_MAX" "_POSIX_NGROUPS_MAX"
"_POSIX_NO_TRUNC" "_POSIX_OPEN_MAX" "_POSIX_PATH_MAX"
"_POSIX_PIPE_BUF" "_POSIX_SAVED_IDS" "_POSIX_SSIZE_MAX"
"_POSIX_STREAM_MAX" "_POSIX_TZNAME_MAX" "_POSIX_VDISABLE"
"_POSIX_VERSION"
SYSTEM CONFIGURATION
Constants
"_SC_ARG_MAX" "_SC_CHILD_MAX" "_SC_CLK_TCK" "_SC_JOB_CONTROL"
"_SC_NGROUPS_MAX" "_SC_OPEN_MAX" "_SC_PAGESIZE" "_SC_SAVED_IDS"
"_SC_STREAM_MAX" "_SC_TZNAME_MAX" "_SC_VERSION"
ERRNO
Constants
"E2BIG" "EACCES" "EADDRINUSE" "EADDRNOTAVAIL" "EAFNOSUPPORT"
"EAGAIN" "EALREADY" "EBADF" "EBADMSG" "EBUSY" "ECANCELED"
"ECHILD" "ECONNABORTED" "ECONNREFUSED" "ECONNRESET" "EDEADLK"
"EDESTADDRREQ" "EDOM" "EDQUOT" "EEXIST" "EFAULT" "EFBIG"
"EHOSTDOWN" "EHOSTUNREACH" "EIDRM" "EILSEQ" "EINPROGRESS"
"EINTR" "EINVAL" "EIO" "EISCONN" "EISDIR" "ELOOP" "EMFILE"
"EMLINK" "EMSGSIZE" "ENAMETOOLONG" "ENETDOWN" "ENETRESET"
"ENETUNREACH" "ENFILE" "ENOBUFS" "ENODATA" "ENODEV" "ENOENT"
"ENOEXEC" "ENOLCK" "ENOLINK" "ENOMEM" "ENOMSG" "ENOPROTOOPT"
"ENOSPC" "ENOSR" "ENOSTR" "ENOSYS" "ENOTBLK" "ENOTCONN"
"ENOTDIR" "ENOTEMPTY" "ENOTRECOVERABLE" "ENOTSOCK" "ENOTSUP"
"ENOTTY" "ENXIO" "EOPNOTSUPP" "EOTHER" "EOVERFLOW" "EOWNERDEAD"
"EPERM" "EPFNOSUPPORT" "EPIPE" "EPROCLIM" "EPROTO"
"EPROTONOSUPPORT" "EPROTOTYPE" "ERANGE" "EREMOTE" "ERESTART"
"EROFS" "ESHUTDOWN" "ESOCKTNOSUPPORT" "ESPIPE" "ESRCH" "ESTALE"
"ETIME" "ETIMEDOUT" "ETOOMANYREFS" "ETXTBSY" "EUSERS"
"EWOULDBLOCK" "EXDEV"
FCNTL
Constants
"FD_CLOEXEC" "F_DUPFD" "F_GETFD" "F_GETFL" "F_GETLK" "F_OK"
"F_RDLCK" "F_SETFD" "F_SETFL" "F_SETLK" "F_SETLKW" "F_UNLCK"
"F_WRLCK" "O_ACCMODE" "O_APPEND" "O_CREAT" "O_EXCL" "O_NOCTTY"
"O_NONBLOCK" "O_RDONLY" "O_RDWR" "O_TRUNC" "O_WRONLY"
FLOAT
Constants
"DBL_DIG" "DBL_EPSILON" "DBL_MANT_DIG" "DBL_MAX"
"DBL_MAX_10_EXP" "DBL_MAX_EXP" "DBL_MIN" "DBL_MIN_10_EXP"
"DBL_MIN_EXP" "FLT_DIG" "FLT_EPSILON" "FLT_MANT_DIG" "FLT_MAX"
"FLT_MAX_10_EXP" "FLT_MAX_EXP" "FLT_MIN" "FLT_MIN_10_EXP"
"FLT_MIN_EXP" "FLT_RADIX" "FLT_ROUNDS" "LDBL_DIG"
"LDBL_EPSILON" "LDBL_MANT_DIG" "LDBL_MAX" "LDBL_MAX_10_EXP"
"LDBL_MAX_EXP" "LDBL_MIN" "LDBL_MIN_10_EXP" "LDBL_MIN_EXP"
FLOATING-POINT ENVIRONMENT
Constants
"FE_DOWNWARD" "FE_TONEAREST" "FE_TOWARDZERO" "FE_UPWARD" on
systems that support them.
LIMITS
Constants
"ARG_MAX" "CHAR_BIT" "CHAR_MAX" "CHAR_MIN" "CHILD_MAX"
"INT_MAX" "INT_MIN" "LINK_MAX" "LONG_MAX" "LONG_MIN"
"MAX_CANON" "MAX_INPUT" "MB_LEN_MAX" "NAME_MAX" "NGROUPS_MAX"
"OPEN_MAX" "PATH_MAX" "PIPE_BUF" "SCHAR_MAX" "SCHAR_MIN"
"SHRT_MAX" "SHRT_MIN" "SSIZE_MAX" "STREAM_MAX" "TZNAME_MAX"
"UCHAR_MAX" "UINT_MAX" "ULONG_MAX" "USHRT_MAX"
LOCALE
Constants
"LC_ALL" "LC_COLLATE" "LC_CTYPE" "LC_MONETARY" "LC_NUMERIC"
"LC_TIME" "LC_MESSAGES" on systems that support them.
MATH
Constants
"HUGE_VAL"
"FP_ILOGB0" "FP_ILOGBNAN" "FP_INFINITE" "FP_NAN" "FP_NORMAL"
"FP_SUBNORMAL" "FP_ZERO" "INFINITY" "NAN" "Inf" "NaN" "M_1_PI"
"M_2_PI" "M_2_SQRTPI" "M_E" "M_LN10" "M_LN2" "M_LOG10E"
"M_LOG2E" "M_PI" "M_PI_2" "M_PI_4" "M_SQRT1_2" "M_SQRT2" on
systems with C99 support.
SIGNAL
Constants
"SA_NOCLDSTOP" "SA_NOCLDWAIT" "SA_NODEFER" "SA_ONSTACK"
"SA_RESETHAND" "SA_RESTART" "SA_SIGINFO" "SIGABRT" "SIGALRM"
"SIGCHLD" "SIGCONT" "SIGFPE" "SIGHUP" "SIGILL" "SIGINT"
"SIGKILL" "SIGPIPE" "SIGQUIT" "SIGSEGV" "SIGSTOP" "SIGTERM"
"SIGTSTP" "SIGTTIN" "SIGTTOU" "SIGUSR1" "SIGUSR2" "SIG_BLOCK"
"SIG_DFL" "SIG_ERR" "SIG_IGN" "SIG_SETMASK" "SIG_UNBLOCK"
"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_ISREG"
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
"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"
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