NAME

POSIX::2008 - Perl interface to POSIX.1-2008

SYNOPSIS

use POSIX::2008 qw(:fcntl openat pwrite);

sysopen my $dh, '/tmp', O_RDONLY|O_DIRECTORY|O_NOFOLLOW
  or die 'Dafuq?';
my $fh = openat($dh, 'foobar', O_RDWR|O_CREAT);
pwrite($fh, 'fuckyounsa', 10, 0);

DESCRIPTION

POSIX::2008 contains many of the interfaces specified by POSIX.1-2008 that the core POSIX module withholds, implements in Perl or fucked up.

It also contains a few nonstandard interfaces present in Linux, BSD and Solaris that are extensions of the POSIX interfaces.

This module is provided "as is" unless someone volunteers to maintain it. Use at your own risk.

FILE DESCRIPTORS AND HANDLES

Since version 0.05, all I/O functions that take numeric file descriptors also accept Perl file or directory handles, except for fdopen() and fdopendir().

Since version 0.22, returned handles support IO::Handle methods.

SYSTEM CALL RETURN VALUES

A system call return value of -1 meaning "error" is mapped to undef except for poll() which returns -1 to be consistent with select().

A system call return value of 0 meaning "success" is mapped to "0 but true".

For system calls where 0 does not just mean "success", 0 is returned unchanged. These are creat(), open(), read(), write(), readv(), writev(), pread(), pwrite(), preadv(), pwritev(), preadv2(), pwritev2(), getpriority(), nice(). openat() gets a special treatment in this regard, see below.

FUNCTIONS

a64l

l = a64l(s);

abort

abort();

abs

ui = abs(i);

Calls llabs(), labs(), or abs(), whichever is the maximum supported by your system.

Note that the library functions use signed integers, so abs(~0) is 1. If you don't want that, use CORE::abs().

access

ret = access(path, mode);

New in version 0.08.

acos

y = acos(x);

acosh

y = acosh(x);

alarm

remaining_sec = alarm(sec);

asin

y = asin(x);

asinh

y = asinh(x);

atan2

z = atan2(y, x);

atan

y = atan(x);

atanh

y = atanh(x);

atof

f = atof(s);

atoi

i = atoi(s);

Calls atoll(), atol(), or atoi(), whichever is the maximum supported by your system. This is of course silly because you could just use int().

Changed in version 0.19: Deprecated atol and atoll now covered by atoi.

basename

s = basename(path);

cabs

r = cabs(re, im);

cacos

(re, im) = cacos(re, im);

cacosh

(re, im) = cacosh(re, im);

carg

phi = carg(re, im);

casin

y = casin(x);

casinh

(re, im) = casinh(re, im);

catan

(re, im) = catan(re, im);

catanh

(re, im) = catanh(re, im);

catclose

ret = catclose(catd);

catgets

s = catgets(catd, set_id, msg_id, dflt_string);

catopen

catd = catopen(name, flag);

cbrt

y = cbrt(x);

ccos

(re, im) = ccos(re, im);

ccosh

(re, im) = ccosh(re, im);

ceil

y = ceil(x);

cexp

(re, im) = cexp(re, im);

New in version 0.19.

chdir

ret = chdir(dir);

dir can be a path, a Perl file or directory handle, or a file descriptor.

Changed in version 0.19: Deprecated fchdir now covered by chdir.

chmod

ret = chmod(what, mode);

what can be a path, a Perl file or directory handle (see "NOTES"), or a file descriptor.

Changed in version 0.19: Deprecated fchmod now covered by chmod.

chown

ret = chown(what, uid, gid);

what can be a path, a Perl file or directory handle (see "NOTES"), or a file descriptor.

Changed in version 0.19: Deprecated fchown now covered by chown.

cimag

im = cimag(re, im);

clock

t = clock()

New in version 0.08.

clock_getcpuclockid

clock_id = clock_getcpuclockid(pid);

pid defaults to 0. Returns undef on error.

clock_getres

(sec, nsec) = clock_getres(clock_id);
floating_sec = clock_getres(clock_id);

clock_id defaults to CLOCK_REALTIME. Returns empty list or undef on error.

Changed in version 0.25: Return floating seconds in scalar context.

clock_gettime

(sec, nsec) = clock_gettime(clock_id);
floating_sec = clock_gettime(clock_id);

clock_id defaults to CLOCK_REALTIME. Returns empty list or undef on error.

Changed in version 0.25: Return floating seconds in scalar context.

clock_nanosleep

(rem_sec, rem_nsec) = clock_nanosleep(clock_id, flags, floating_sec);
floating_rem_sec = clock_nanosleep(clock_id, flags, floating_sec);

(rem_sec, rem_nsec) = clock_nanosleep(clock_id, flags, sec, nsec);
floating_rem_sec = clock_nanosleep(clock_id, flags, sec, nsec);

Returns zero(es) on success, the remaining time on EINTR, the empty list or undef otherwise. The remaining time is zero if the flag TIMER_ABSTIME is set.

Changed in version 0.25: Sleep time can be floating seconds only or seconds and nanoseconds.

clock_settime

ret = clock_settime(clock_id, sec, nsec);
ret = clock_settime(clock_id, floating_sec);

Changed in version 0.25: Time can be floating seconds only or seconds and nanoseconds.

clog

(re, im) = clog(re, im);

close

ret = close(fd);

confstr

s = confstr(name);

name is one of the _CS_* integer constants.

Returns undef on error.

conj

(re, im) = conj(re, im);

copysign

xs = copysign(x, y);

cos

y = cos(x);

cosh

y = cosh(x);

cpow

(re, im) = cpow(re_x, im_x, re_y, im_y);

cproj

(re, im) = cproj(re, im);

creal

re = creal(re, im);

creat

ret = creat(path, mode=0666);

New in version 0.22.

csin

(re, im) = csin(re, im);

csinh

(re, im) = csinh(re, im);

csqrt

(re, im) = csqrt(re, im);

ctan

(re, im) = ctan(re, im);

ctanh

(re, im) = ctanh(re, im);

dirname

name = dirname(path);

div

(quot, rem) = div(numer, denom);

Calls lldiv(), ldiv(), or div(), whichever is the maximum supported by your system.

Note that the library functions use signed integers, so div(~0, 1) is (-1, 0). If you don't want that, use Perls int(), / and %.

Changed in version 0.19: Deprecated ldiv and lldiv now covered by div.

dlclose

dlclose(dlhandle);

dlerror

dlerror();

dlopen

dlhandle = dlopen(file, mode);

dlsym

addr = dlsym(dlhandle, name);

drand48

r = drand48();

endutxent

endutxent();

erand48

(r, X0, X1, X2) = erand48(X0, X1, X2);

erf

y = erf(x);

erfc

y = erfc(x);

execveat

execveat(dirfd, path, args, env=undef, flags=0);

The execveat() system call is a nonstandard extension present in Linux. See also fexecve().

It executes the program referred to by path, which is interpreted relative to dirfd as with the other *at functions, passing args as its command-line arguments and optionally env as its environment.

args must be an array reference and, by convention, args->[0] should be the name of the program being executed.

env must be a hash reference. If omitted or undef, the environment of the calling proces is used (which you can manipulate via %ENV).

flags is a bit mask that can include zero or more of the flags AT_EMPTY_PATH, AT_SYMLINK_NOFOLLOW.

path is executed "as is", i.e. no PATH search or interpretation of shell metacharacters takes place as opposed to Perl's built-in exec.

Returns undef on error, otherwise it doesn't return.

Usage example:

sysopen my $dh, '/usr', O_DIRECTORY|O_PATH;
execveat($dh, 'bin/date', [qw(date +%T)], {TZ => 'UTC'}, AT_SYMLINK_NOFOLLOW);

New in version 0.22.

exp

y = exp(x);

exp2

y = exp2(x);

expm1

y = expm1(x);

faccessat

ret = faccessat(dirfd, path, amode, flags=0);

flags is the bitwise OR of zero or more of AT_EACCESS, AT_SYMLINK_NOFOLLOW.

fchmodat

ret = fchmodat(dirfd, path, mode, flags=0);

flags can be 0 or AT_SYMLINK_NOFOLLOW. Your system might support a different set of flags.

fchownat

ret = fchownat(dirfd, path, uid, gid, flags=0);

flags can be 0 or AT_SYMLINK_NOFOLLOW. Your system might support a different set of flags.

fdatasync

ret = fdatasync(fd);

fdopen

ret = fdopen(fd, mode);

Returns a file handle associated with the numeric file descriptor fd or undef on error. mode is one of the values "r", "w", "a" with an optional "+" and/or "b".

The file descriptor is not dup'ed and will be closed when the handle is closed.

It's similar to IO::Handle::new_from_fd() with the following improvements:

• It really calls fdopen(3).

• It expects POSIX mode strings (e.g. "r", not "<").

• It fails if mode is not compatible with the flags of fd.

Usage example:

my $fh = do {
  opendir my $dh, '.';
  fdopen(POSIX::dup(fileno $dh), 'r');
};
chmod 0700, $fh;  # this would fail with $dh from opendir

New in version 0.05.

Changed in version 0.22: fd can no longer be a handle (that was a wrong turn).

fdopendir

ret = fdopendir(fd);

Returns a directory handle associated with the numeric file descriptor fd or undef on error.

The file descriptor is not dup'ed and will be closed when the handle is closed.

Usage example:

my $dh = do {
  sysopen my $fh, '/tmp', O_RDONLY|O_DIRECTORY|O_NOFOLLOW;
  fdopendir(POSIX::dup(fileno $fh));
};
my @dents = readdir $dh;  # this would fail with $fh from sysopen

New in version 0.05.

Changed in version 0.22: fd can no longer be a handle (that was a wrong turn).

fdim

d = fdim(double x, double y);

feclearexcept

ret = feclearexcept(excepts);

Returns 0 but true on success, undef on error.

New in version 0.20.

fegetround

rounding_mode = fegetround();

feraiseexcept

ret = feraiseexcept(excepts);

Returns 0 but true on success, undef on error.

New in version 0.20.

fesetround

ret = fesetround(round);

Returns 0 but true on success, undef on error.

fetestexcept

excepts_currently_set = fetestexcept(excepts);

New in version 0.20.

fexecve

fexecve(fd, args, env=undef);

Executes the program referred to by the file descriptor fd, passing args as its command-line arguments and optionally env as its environment.

args must be an array reference and, by convention, args->[0] should be the name of the program being executed.

env must be a hash reference. If omitted or undef, the environment of the calling proces is used (which you can manipulate via %ENV).

See the manpage for issues regarding the close-on-exec flag and the /proc filesystem.

Returns undef on error, otherwise it doesn't return.

Usage example:

sysopen my $fh, '/usr/bin/date', O_PATH;
fexecve($fh, [qw(date +%T)], {TZ => 'UTC'});

See also execveat().

New in version 0.22.

ffs

pos = ffs(i);

Calls ffsll(), ffsl(), or ffs(), whichever is the maximum available on your system.

floor

y = floor(x);

fma

r = fma(x, y, z);

fmax

m = fmax(x, y);

fmin

m = fmin(x, y);

fmod

m = fmod(x, y);

fnmatch

ret = fnmatch(pattern, string, flags);

Returns 0 if string matches pattern, FNM_NOMATCH if there is no match, undef if there is an error.

flags is the bitwise OR of zero or more of FNM_NOESCAPE, FNM_PATHNAME, FNM_PERIOD, FNM_FILE_NAME, FNM_LEADING_DIR, FNM_CASEFOLD.

fpclassify

fpclassify(x);

Returns one of FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL.

fstatat

(dev, ino, mode, nlink, uid, gid, rdev, size, atim_sec, mtim_sec, ctim_sec, blksize, blocks, atim_nsec, mtim_nsec, ctim_nsec) = fstatat(dirfd, path, flags = 0);

flags is the bitwise OR of zero or more of AT_SYMLINK_NOFOLLOW, AT_NO_AUTOMOUNT. Your system might support a different set of flags.

See stat() for notes on the return values and bugs in CORE::stat().

Returns the empty list on error.

fsync

ret = fsync(fd);

futimens

ret = futimens(fd, atime_sec, atime_nsec, mtime_sec, mtime_nsec);

atime_sec and mtime_sec default to 0, atime_nsec and mtime_nsec default to UTIME_NOW.

getdate

(sec, min, hour, mday, mon, year, wday, yday, isdst) = getdate(string);

getdate_err

getdate_err() returns the value of the getdate_err variable.

getegid

egid = getegid();

geteuid

euid = geteuid();

getgid

gid = getgid();

gethostid

hostid = gethostid();

gethostname

hostname = gethostname();

getitimer

(int_sec, int_usec, val_sec, val_usec) = getitimer(which);

which can be one of ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF.

POSIX.1-2008 marks getitimer() and setitimer() obsolete, recommending the use of the POSIX timers API (timer_gettime(), timer_settime(), etc.) instead.

POSIX.1-2024 removed getitimer() and setitimer().

getpriority

prio = getpriority(which=PRIO_PROCESS, who=0);

which can be one of PRIO_PROCESS, PRIO_PGRP, PRIO_USER, defaults to PRIO_PROCESS. who defaults to 0.

Returns undef on error.

getsid

sid = getsid(pid);

pid defaults to 0.

getuid

uid = getuid();

getutxent

(user, id, line, pid, type, sec, usec) = getutxent();

getutxent() reads a line from the current file position in the utmp file.

getutxid

(user, id, line, pid, type, sec, usec) = getutxid(ut_type, ut_id);

getutxid() searches forward from the current file position in the utmp file based upon ut_type and ut_id. If ut_type is one of RUN_LVL, BOOT_TIME, NEW_TIME, or OLD_TIME, getutxid() will find the first entry whose ut_type field matches ut_type. If ut_type is one of INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, getutxid() will find the first entry whose ut_id field matches ut_id.

getutxline

(user, id, line, pid, type, sec, usec) = getutxline(ut_line);

getutxline() searches forward from the current file position in the utmp file. It scans entries whose ut_type is USER_PROCESS or LOGIN_PROCESS and returns the first one whose ut_line field matches ut_line.

hypot

r = hypot(x, y);

ilogb

y = ilogb(x);

isalnum

ret = isalnum(charstring);

Like POSIX::isalnum() but returns 0 for the empty string.

isalpha

ret = isalpha(charstring);

Like POSIX::isalpha() but returns 0 for the empty string.

isascii

ret = isascii(charstring);

POSIX.1-2008 marks it as obsolete and it was removed in POSIX.1-2024, but I include it anyway.

New in version 0.19.

isatty

ret = isatty(fd);

isblank

ret = isblank(charstring);

Like POSIX::isblank() but returns 0 for the empty string.

iscntrl

ret = iscntrl(charstring);

Like POSIX::iscntrl() but returns 0 for the empty string.

isdigit

ret = isdigit(charstring);

Like POSIX::isdigit() but returns 0 for the empty string.

isfinite

ret = isfinite(x);

isgraph

ret = isgraph(charstring);

Like POSIX::isgraph() but returns 0 for the empty string.

isgreaterequal

ret = isgreaterequal(x, y);

New in version 0.20.

isinf

ret = isinf(x);

isless

ret = isless(x, y);

New in version 0.20.

islessequal

ret = islessequal(x, y);

New in version 0.20.

islessgreater

ret = islessgreater(x, y);

New in version 0.20.

islower

ret = islower(charstring);

Like POSIX::islower() but returns 0 for the empty string.

isnan

ret = isnan(x);

isnormal

ret = isnormal(x);

isprint

ret = isprint(charstring);

Like POSIX::isprint() but returns 0 for the empty string.

ispunct

ret = ispunct(charstring);

Like POSIX::ispunct() but returns 0 for the empty string.

isspace

ret = isspace(charstring);

Like POSIX::isspace() but returns 0 for the empty string.

isunordered

ret = isunordered(x, y);

New in version 0.20.

isupper

ret = isupper(charstring);

Like POSIX::isupper() but returns 0 for the empty string.

isxdigit

ret = isxdigit(charstring);

Like POSIX::isxdigit() but returns 0 for the empty string.

j0

y = j0(x);

j0() is the Bessel function of the first kind of order 0.

j1

y = j1(x);

j1() is the Bessel function of the first kind of order 1.

jn

y = jn(n, x);

jn() is the Bessel function of the first kind of order n.

jrand48

(r, X0, X1, X2) = jrand48(X0, X1, X2);

killpg

ret = killpg(pgrp, sig);

l64a

s = l64a(n);

lchown

ret = lchown(path, uid, gid);

New in version 0.08.

ldexp

y = ldexp(x, exp);

lgamma

y = lgamma(x);

link

ret = link(path1, path2);

linkat

ret = linkat(fd1, path1, fd2, path2, flags=0);

flags can be 0 or AT_SYMLINK_FOLLOW. Your system might support a different set of flags.

log

y = log(x);

log10

y = log10(x);

log1p

y = log1p(x);

log2

y = log2(x);

logb

y = logb(x);

lrand48

r = lrand48();

lround

l = lround(x);

Calls llround() or lround() whichever is the maximum available on your system. If the rounded value is outside Perl's internal signed integer range, it is returned as a string. If the rounded value is too large to be stored in a long long or long, undef is returned.

lstat

(dev, ino, mode, nlink, uid, gid, rdev, size, atim_sec, mtim_sec, ctim_sec, blksize, blocks, atim_nsec, mtim_nsec, ctim_nsec) = lstat(path);

path is assumed to be a string (or will be converted to a string).

See stat() for notes on the return values and bugs in CORE::stat().

Returns the empty list on error.

mkdir

ret = mkdir(path, [mode = 0777]);

mkdirat

ret = mkdirat(fd, path, mode);

mkdtemp

name = mkdtemp(template);

mkfifo

ret = mkfifo(path, mode);

mkfifoat

ret = mkfifoat(fd, path, mode);

mknod

ret = mknod(path, mode, dev);

mknodat

ret = mknodat(fd, path, mode, dev);

mkstemp

(fd, name) = mkstemp(template);

mrand48

mrand48();

nanosleep

(rem_sec, rem_nsec) = nanosleep(floating_sec);
floating_rem_sec = nanosleep(floating_sec);

(rem_sec, rem_nsec) = nanosleep(sec, nsec);
floating_rem_sec = nanosleep(sec, nsec);

Returns zero(es) on success, the remaining time on EINTR, the empty list or undef otherwise.

Changed in version 0.25: Sleep time can be floating seconds only or seconds and nanoseconds.

nearbyint

y = nearbyint(x);

nextafter

z = nextafter(x, y);

nexttoward

z = nexttoward(x, y);

nice

ret = nice(incr);

Returns undef on error.

nrand48

r = nrand48()

open

ret = open(path, flags=O_RDONLY, mode=0666);

openat

ret = openat(dirfd, path, flags=O_RDONLY, mode=0666);

If dirfd is numeric (i.e. a file descriptor), openat() returns a file descriptor. If dirfd is a file or directory handle, the return value is also a handle whose type depends on the file type of path: If path is a directory, the return value is a directory handle, otherwise it's a file handle.

To get a handle even for the special numeric dirfd value AT_FDCWD, you can pass a reference to that value instead, i.e. openat(\AT_FDCWD, ...).

Returns undef on error.

Changed in version 0.18: Support added for \AT_FDCWD reference.

openat2

ret = openat2(dirfd, path, how);

The openat2() system call is a Linux-specific extension of openat() and provides a superset of its functionality.

The how parameter is a hash reference corresponding to the struct open_how. It currently supports the keys flags, mode and resolve. Missing keys are treated as having a zero value.

Example:

my $fh = openat2(
  \AT_FDCWD, '/foobar',
  {flags => O_RDWR|O_CREAT, mode => 0600, resolve => RESOLVE_IN_ROOT}
);

Note that, unlike open() or openat(), openat2() is very picky about flags and mode. See the manpage for details.

Returns undef on error.

New in version 0.18.

pathconf

ret = pathconf(what, name);

what can be a path or, if your system supports fpathconf(), a Perl file or directory handle or a file descriptor.

name is one of the _PC_* integer constants.

Returns undef on error.

New in version 0.22.

poll

ret = poll(pollfds, timeout=-1);

timeout specifies the number of milliseconds that poll() should block waiting for a file descriptor to become ready. A negative timeout value means an infinite timeout. A timeout of zero causes poll() to return immediately.

pollfds is an array reference holding array references of the form [fd, events, revents] where fd is an integer file descriptor or a file handle, events is a bit mask of events you are interested in for fd, and revents is a bit mask of events that actually occurred.

revents is changed by the call (unless a timeout or error occurs), everything else remains unchanged.

If fd is negative or anything sv_2io() doesn't consider a file handle then the corresponding events field is ignored and the revents field returns zero.

Returns the number of elements in pollfds whose revents have been set to a non-zero value, zero if the call timed out, -1 on error.

Usage example:

open my $pipe, '-|', qw(tail -f /var/log/messages);
my $pollfds = [[\*STDIN, POLLIN, 0], [2, POLLOUT, 0], [$pipe, POLLIN, 0]];
my $rv = poll($pollfds, -1);

# Skip events for fd 2 this time:
my $pollfds = [[\*STDIN, POLLIN, 0], [-2, POLLOUT, 0], [$pipe, POLLIN, 0]];
my $rv = poll($pollfds, -1);

New in version 0.25.

posix_fadvise

ret = posix_fadvise(fd, offset, len, advice);

advice is one of the POSIX_FADV_ constants.

New in version 0.14.

posix_fallocate

ret = posix_fallocate(fd, offset, len);

New in version 0.14.

pread

bytes_read = pread(fd, buf, count, offset=0, buf_offset=0);

pread() reads count bytes (not characters) of data from the file descriptor fd at file offset offset into the scalar buf without changing the file offset. buf will be enlarged automatically if necessary.

offset and buf_offset are set to 0 if omitted or undef.

pread() treats buf just like sysread() does: buf_offset may be specified to place the read data at that position in buf. If buf_offset is past the end of buf, buf will be padded with zeros before appending the data. If buf_offset is negative, it is counted from the end of the string. buf will be grown or shrunk so that the last byte actually read is the last byte of buf after the read.

Returns the number of bytes read, 0 at EOF, undef on error.

Croaks if buf is read-only and count is non-zero.

Changed in version 0.13: Argument order is now (count, offset) instead of (offset, count).

Changed in version 0.22: Croak with read-only buf and non-zero count.

preadv

bytes_read = preadv(fd, buffers, sizes, offset=0);

preadv() behaves like readv() but adds an optional offset argument, which specifies the file position at which the data is to be read. offset is set to 0 if omitted or undef.

The file offset is not changed by this system call. The file referred to by fd must be capable of seeking.

This syscall is present in Linux and BSD.

New in version 0.13.

preadv2

bytes_read = preadv2(fd, buffers, sizes, offset=0, flags=0);

preadv2() is similar to preadv() but adds an optional flags argument, which is a bitwise OR of zero or more of the RWF_* flags (see the manpage for details). flags is set to 0 if omitted or undef.

This syscall is Linux-specific.

New in version 0.20.

psignal

psignal(sig, msg);

New in version 0.25.

ptsname

name = ptsname(fd);

Changed in version 0.19: Calls ptsname_r() if available.

Changed in version 0.22: fd may also be a file handle.

pwrite

bytes_written = pwrite(fd, buf, count=undef, offset=0, buf_offset=0);

pwrite() writes count bytes of data from the scalar buf to the file descriptor fd at file offset offset without changing the file offset. The file referenced by fd must be capable of seeking.

If count is omitted or undef, everything from buf_offset up to the end of buf is written.

buf_offset may be specified to write data from that position in buf. If buf_offset is negative it is counted from the end of the string.

offset and buf_offset are set to 0 if omitted or undef.

Returns the number of bytes written, undef on error.

On Linux, if a file is opened with O_APPEND, pwrite() appends data to the end of the file, regardless of the value of offset (in violation of POSIX).

Changed in version 0.13: Argument order is now (count, offset) instead of (offset, count).

pwritev

bytes_written = pwritev(fd, buffers, offset=0);

pwritev() behaves like writev() but adds an optional offset argument, which specifies the file position at which the data is to be written. offset is set to 0 if omitted or undef.

The file offset is not changed by this system call. The file referred to by fd must be capable of seeking.

On Linux, if a file is opened with O_APPEND, pwritev() appends data to the end of the file, regardless of the value of offset (in violation of POSIX).

This syscall is present in Linux and BSD.

New in version 0.08.

pwritev2

bytes_written = pwritev2(fd, buffers, offset=0, flags=0);

pwritev2() is similar to pwritev() but adds an optional flags argument, which is a bitwise OR of zero or more of the RWF_* flags (see the manpage for details). flags is set to 0 if omitted or undef.

This syscall is Linux-specific.

New in version 0.20.

random

r = random();

raise

ret = raise(sig);

read

bytes_read = read(fd, buf, count);

Like POSIX::read() but returns 0 at EOF instead of 0 but true. Croaks if buf is read-only and count is non-zero.

Changed in version 0.22: Croak with read-only buf and non-zero count.

readv

bytes_read = readv(fd, buffers, sizes);

readv() reads from the file descriptor fd into buffers as many strings as there are elements in sizes.

buffers must be a variable holding an array (@buf), an array reference or undef ($buf). If it is undef it will be upgraded to an array reference.

sizes must be an array reference, i.e. \@sizes, $sizes, or [...].

sizes is expected to hold unsigned integers that specify how many bytes are to be read into each buffer. A byte count of 0 or undef creates an empty string. sizes is processed in array order.

buffers will be extended if necessary, but it will never be shrunk. If buffers is not empty, any existing elements are replaced as long as sufficient data was read from fd.

readv() returns the number of bytes read, undef on error.

Note that it is not an error for a successful call to transfer fewer bytes than requested. In this case there may be one "partially" filled buffer, i.e. it contains fewer bytes than the corresponding size. Surplus size entries lead to corresponding empty buffers.

Usage example:

my $fh = openat(\AT_FDCWD, '/tmp/foobar', O_RDWR|O_CREAT|O_TRUNC);
pwrite($fh, 'foobar', 6, 0);
readv($fh, my $buf1, [3, 0, 8]); # $buf1: ['foo', '', 'bar']
sysseek $fh, 0, 0;
readv($fh, my @buf2, [1, 3, 2]); # @buf2: ('f', 'oob', 'ar')

New in version 0.13.

Changed in version 0.22: buffers may be an undef variable, buffers beyond EOF are created as empty strings instead of being skipped.

readlink

name = readlink(path);

Returns undef on error.

readlinkat

name = readlinkat(dirfd, path);

Returns undef on error.

realpath

resolved_path = realpath(path);

Calls the actual C library fuction realpath() and relies on it to be able to allocate memory for the resolved path automatically (as required by POSIX-2008).

Returns undef on error.

New in version 0.18.

remainder

rem = remainder(x, y);

Returns undef on error.

remove

ret = remove(path);

Calls the actual C library function remove().

Note that core POSIX::remove() fails if path is a symlink to a directory because someone "couldn't read the plans right and did a piss-poor job of putting it together" as (-d $_[0]) ? CORE::rmdir($_[0]) : CORE::unlink($_[0]). Quote from Armageddon.

This could be fixed like this: unlink $_[0] or ($!{EISDIR} or $!{EPERM}) and rmdir $_[0] (correct errno check depends on OS), or by using the library call right away.

removeat

ret = removeat(dirfd, path);

The removeat() function works exactly like remove() but path is interpreted relative to dirfd as with the other *at functions.

This function is a home-grown non-standard extension only available in this module (to my knowledge).

New in version 0.22.

remquo

(rem, quo) = remquo(x, y);

Returns the empty list on error.

New in version 0.20.

rename

ret = rename(old, new);

renameat

ret = renameat(olddirfd, oldpath, newdirfd, newpath);

renameat2

ret = renameat(olddirfd, oldpath, newdirfd, newpath, flags=0);

The renameat2() system call is a Linux-specific extension of renameat() and provides a superset of its functionality.

flags is the bitwise OR of zero or more of RENAME_EXCHANGE, RENAME_NOREPLACE, RENAME_WHITEOUT.

New in version 0.21.

rmdir

ret = rmdir(path);

New in version 0.19.

round

r = round(x);

scalbn

y = scalbn(x, n);

Calls scalbln() or scalbn(), whichever is the maximum supported by your system.

seed48

(old_seed1, old_seed2, old_seed3) = seed48(seed1, seed2, seed3);

setegid

ret = setegid(gid);

seteuid

ret = seteuid(uid);

setgid

ret = setgid(gid);

setitimer

(old_int_sec, old_int_usec, old_val_sec, old_val_usec) = setitimer(which, int_sec, int_usec, val_sec, val_usec);

which is one of ITIMER_REAL, ITIMER_VIRTUAL, ITIMER_PROF.

POSIX.1-2008 marks getitimer() and setitimer() obsolete, recommending the use of the POSIX timers API (timer_gettime(), timer_settime(), etc.) instead.

POSIX.1-2024 removed getitimer() and setitimer().

setpriority

ret = setpriority(prio, which=PRIO_PROCESS, who=0);

which can be one of PRIO_PROCESS, PRIO_PGRP, PRIO_USER, defaults to PRIO_PROCESS. who defaults to 0.

Note that due to the support of default values for which and who, prio is the first call parameter, whereas in the actual syscall it is the last.

Returns true on success, undef on error.

setregid

ret = setregid(rgid, egid);

setreuid

ret = setreuid(ruid, euid);

setsid

sid = setsid();

New in version 0.19.

setuid

ret = setuid(uid);

setutxent

setutxent();

sighold

ret = sighold(sig);

POSIX.1-2008 marks this function as obsolete, recommending the use of "sigprocmask" in POSIX instead.

sigignore

ret = sigignore(sig);

POSIX.1-2008 marks this function as obsolete, recommending the use of "sigaction" in POSIX instead. Or use $SIG{SIG} = 'IGNORE';.

signbit

b = signbit(x);

sigpause

sigpause(sig);

POSIX.1-2008 marks this function as obsolete, recommending the use of "sigsuspend" in POSIX instead.

sigrelse

ret = sigrelse(sig);

POSIX.1-2008 marks this function as obsolete, recommending the use of "sigprocmask" in POSIX instead.

sin

y = sin(x);

New in version 0.19.

sinh

y = sinh(x);

srand48

srand48(seedval);

srandom

srandom(seed);

stat

(dev, ino, mode, nlink, uid, gid, rdev, size, atim_sec, mtim_sec, ctim_sec, blksize, blocks, atim_nsec, mtim_nsec, ctim_nsec) = stat(what);

what can be a path, a Perl file handle or a file descriptor.

ctim_sec, blksize, blocks and nanoseconds may not be available on your system.

Values outside Perl's internal integer range are returned as strings, i.e. if you need the exact values you should, for example, use eq instead of == for comparisons.

Note that CORE::stat() lies to you in some cases: It returns rdev as a signed integer even if your OS's dev_t is unsigned. It returns size as a floating point number if your OS's off_t is bigger than Perl's integer size. It returns the times as floating point numbers if your OS's time_t is unsigned.

POSIX::2008::stat() doesn't mimic these bugs and uses the correct data types for all values.

Returns the empty list on error.

statvfs

(f_bsize, f_frsize, f_blocks, f_bfree, f_bavail, f_files, f_ffree, f_favail, f_fsid, f_flag, f_namemax) = statvfs(what);

what can be a path, a Perl file handle or a file descriptor.

Values outside Perl's internal integer range are returned as strings as with stat(). Note that Filesys::Statvfs returns only floating point numbers which may give wrong results, and it lacks f_fsid.

Only the ST_NOSUID and ST_RDONLY flags of the f_flag field are specified in POSIX but this module provides additional ST_ flags if available.

Returns the empty list on error.

New in version 0.25.

strptime

(sec, min, hour, mday, mon, year, wday, yday, isdst) =
  strptime(s, format[, sec, min, hour, mday, mon, year, wday, yday, isdst]);

... = strptime(s, format, \@tm);

strptime() converts the string s into a broken-down time according to the format string format.

The time fields may optionally be initialized in whole or in part either with up to 9 separate arguments or with a single array reference after the format. Omitted arguments are treated as undef. In case of an array reference the array is updated according to the fields affected by the format string. If an error occurred the array is not udpated.

In list context returns the broken-down time or the empty list on error. Fields not affected by the format string are returned as initialized.

In scalar context returns the index of the first byte in s that was not processed or the byte length of s if the whole string was consumed or undef on error.

As strptime() acts on null-terminated strings, strings containing NUL bytes will only be processed up to the first NUL byte.

New in version 0.02.

Changed in version 0.24: Accept an array reference as the third argument (https://rt.cpan.org/Public/Bug/Display.html?id=66519).

strsignal

str = strsignal(sig);

New in version 0.25.

symlink

ret = symlink(target, linkpath);

symlinkat

ret = symlinkat(target, dirfd, linkpath);

sync

sync();

This function doesn't return any value.

sysconf

ret = sysconf(name);

name is one of the _SC_* integer constants.

Returns undef on error.

New in version 0.22.

tan

y = tan(x);

tanh

y = tanh(x);

tgamma

y = tgamma(x);

timer_create

timerid = timer_create(clockid, signal=undef);

Creates a new per-process interval timer using the clock given by clock_id as the timing base. signal is the signal number to be delivered when the timer expires. If signal is omitted or undef, no signal is delivered and the progress of the timer can be monitored using timer_gettime().

Calling a notification function on timer expiration is currently not supported.

Returns undef on error.

New in version 0.16.

Changed in version 0.22: signal is optional.

timer_delete

ret = timer_delete(timerid);

Returns 0 but true on success, undef on error.

New in version 0.16.

timer_getoverrun

count = timer_getoverrun(timerid);

Returns undef on error.

New in version 0.16.

timer_gettime

(interval_sec, interval_nsec, initial_sec, initial_nsec) = timer_gettime(timerid);

Returns the empty list on error.

New in version 0.16.

timer_settime

(old_int_sec, old_int_nsec, old_init_sec, old_init_nsec) = timer_settime(timerid, flags, int_sec, int_nsec, [init_sec, init_nsec]);

flags may be 0 or TIMER_ABSTIME. If the init values are omitted, they are set to the int values.

New in version 0.16.

truncate

ret = truncate(what, length);

what can be a path, a Perl file handle, or a file descriptor.

Note that it does not flush the file handle before truncating. Perl's built-in truncate() does (this is undocumented, probably because it's silly).

Changed in version 0.19: Deprecated ftruncate now covered by truncate.

trunc

y = trunc(x);

ttyname

name = ttyname(fd);

Calls ttyname_r() if available.

New in version 0.19.

Changed in version 0.22: fd may also be a file handle.

unlink

ret = unlink(path);

Calls the actual C library function unlink().

Note that core POSIX::unlink() calls CORE::unlink(), which, unless you start Perl with -U, a) is prone to time-of-check/time-of-use race conditions due to an additional lstat(), and b) blindly fails with EISDIR for directories (due to said lstat()), ignoring that some OSes use EPERM in this case (as required by POSIX).

unlinkat

ret = unlinkat(dirfd, path, flags=0);

flags can be 0 or AT_REMOVEDIR.

utimensat

ret = utimensat(dirfd, path, flags, atime_sec, atime_nsec, mtime_sec, mtime_nsec);

flags can be 0 or AT_SYMLINK_NOFOLLOW, defaults to 0. Your system might support a different set of flags.

atime_sec and mtime_sec default to 0. atime_nsec and mtime_nsec default to UTIME_NOW.

write

bytes_written = write(fd, buf, count=undef);

Like POSIX::write() but returns 0 instead of 0 but true if 0 bytes were written, and never writes more bytes than buf contains even if count exceeds the length of buf.

If count is omitted or undef, it defaults to the length of buf.

writev

bytes_written = writev(fd, buffers);

writev() writes multiple buffers of data to the file associated with the file descriptor fd.

buffers must be an array reference, i.e. \@buf, $buf or [...]. The buffers are processed in array order.

Note that writev($fh, $buf); is not the same as print $fh, @$buf; or syswrite $fh, $_ for @$buf; because writev() transfers data atomically as a single block. See the manpage for details.

Returns the number of bytes written or undef on error.

New in version 0.08.

y0

y = y0(x);

y0() is the Bessel function of the second kind of order 0.

y1

y = y1(x);

y1() is the Bessel function of the second kind of order 1.

yn

y = yn(n, x);

yn() is the Bessel function of the second kind of order n.

EXPORTS

This module does not export anything by default. The following export tags are available:

:at      All *at() functions like openat(), all AT_/RENAME_/RESOLVE_ constants
:id      All get/set*id() functions like getuid() etc.
:is      All is* functions like isdigit() etc.
:rw      read(), readv(), write(), writev()
:prw     pread(), preadv(), preadv2(), pwrite(), pwritev(), pwritev2()
:clock   All clock* functions and CLOCK_ constants and TIMER_ABSTIME
:fcntl   All F_, FD_, O_, POSIX_FADV_, SEEK_, _OK constants (for AT_ use :at)
:fenv_h  All FE_ constants and fe* functions
:fnm     fnmatch() and all FNM_ constants
:poll    poll() and all POLL constants
:stat_h  All S_I* and UTIME_ constants
:time_h  All CLOCK_ and TIMER_ constants
:timer   All timer_ functions and TIMER_ constants
:utmpx_h   All *utx* functions and utmpx.h constants
:confstr   confstr() and all _CS_ constants
:pathconf  pathconf() and all _PC_ constants
:sysconf   sysconf() and all _SC_ constants

New in version 0.19: :stat_h export tag.

New in version 0.20: :fenv_h export tag.

New in version 0.22: :confstr, :pathconf, :sysconf export tags.

New in version 0.25: :poll export tag.

CONSTANTS

AT_EACCESS AT_EMPTY_PATH AT_FDCWD AT_NO_AUTOMOUNT AT_REMOVEDIR AT_RESOLVE_BENEATH AT_SYMLINK_FOLLOW AT_SYMLINK_NOFOLLOW RENAME_EXCHANGE RENAME_NOREPLACE RENAME_WHITEOUT RESOLVE_BENEATH RESOLVE_CACHED RESOLVE_IN_ROOT RESOLVE_NO_MAGICLINKS RESOLVE_NO_SYMLINKS RESOLVE_NO_XDEV

ACCOUNTING EMPTY BOOT_TIME NEW_TIME OLD_TIME DEAD_PROCESS INIT_PROCESS LOGIN_PROCESS USER_PROCESS RUN_LVL

CLOCK_BOOTTIME CLOCK_BOOTTIME_ALARM CLOCK_HIGHRES CLOCK_MONOTONIC CLOCK_MONOTONIC_COARSE CLOCK_MONOTONIC_FAST CLOCK_MONOTONIC_PRECISE CLOCK_MONOTONIC_RAW CLOCK_PROCESS_CPUTIME_ID CLOCK_REALTIME CLOCK_REALTIME_ALARM CLOCK_REALTIME_COARSE CLOCK_REALTIME_FAST CLOCK_REALTIME_PRECISE CLOCK_SOFTTIME CLOCK_TAI CLOCK_THREAD_CPUTIME_ID CLOCK_UPTIME CLOCK_UPTIME_FAST CLOCK_UPTIME_PRECISE

F_DUPFD F_DUPFD_CLOEXEC F_GETFD F_SETFD F_GETFL F_SETFL F_GETLK F_SETLK F_SETLKW F_GETOWN F_SETOWN F_RDLCK F_UNLCK F_WRLCK

FD_CLOEXEC

FE_ALL_EXCEPT FE_DIVBYZERO FE_INEXACT FE_INVALID FE_OVERFLOW FE_UNDERFLOW FE_TONEAREST FE_TOWARDZERO FE_UPWARD FE_DOWNWARD

FNM_CASEFOLD FNM_FILE_NAME FNM_LEADING_DIR FNM_NOESCAPE FNM_NOMATCH FNM_PATHNAME FNM_PERIOD

FP_INFINITE FP_NAN FP_NORMAL FP_SUBNORMAL FP_ZERO

TIMER_ABSTIME ITIMER_PROF ITIMER_REAL ITIMER_VIRTUAL

O_ACCMODE O_APPEND O_ASYNC O_CLOEXEC O_CREAT O_DIRECT O_DIRECTORY O_DSYNC O_EMPTY_PATH O_EXCL O_EXEC O_EXLOCK O_LARGEFILE O_NDELAY O_NOATIME O_NOCTTY O_NOFOLLOW O_NONBLOCK O_NOSIGPIPE O_PATH O_RDONLY O_REGULAR O_RESOLVE_BENEATH O_RDWR O_RSYNC O_SEARCH O_SHLOCK O_SYNC O_TMPFILE O_TRUNC O_TTY_INIT O_WRONLY FASYNC

POLLIN POLLRDNORM POLLRDBAND POLLPRI POLLOUT POLLWRNORM POLLWRBAND POLLERR POLLHUP POLLNVAL

INFTIM POLLFREE POLLINIGNEOF POLLMSG POLLNORM POLLRDHUP POLLREMOVE POLLSTANDARD POLL_BUSY_LOOP

POSIX_FADV_NORMAL POSIX_FADV_SEQUENTIAL POSIX_FADV_RANDOM POSIX_FADV_NOREUSE POSIX_FADV_WILLNEED POSIX_FADV_DONTNEED

PRIO_PROCESS PRIO_PGRP PRIO_USER

RTLD_DEEPBIND RTLD_GLOBAL RTLD_LAZY RTLD_LOCAL RTLD_MEMBER RTLD_NOAUTODEFER RTLD_NODELETE RTLD_NOLOAD RTLD_NOW

RWF_APPEND RWF_DSYNC RWF_HIPRI RWF_NOWAIT RWF_SYNC

SEEK_SET SEEK_CUR SEEK_END SEEK_DATA SEEK_HOLE F_OK R_OK W_OK X_OK

S_IFMT S_IFBLK S_IFCHR S_IFIFO S_IFREG S_IFDIR S_IFLNK S_IFSOCK S_ISUID S_ISGID S_IRWXU S_IRUSR S_IWUSR S_IXUSR S_IRWXG S_IRGRP S_IWGRP S_IXGRP S_IRWXO S_IROTH S_IWOTH S_IXOTH S_ISVTX

ST_NOSUID ST_RDONLY

ST_MANDLOCK ST_NOATIME ST_NODEV ST_NODIRATIME ST_NOEXEC ST_RELATIME ST_SYNCHRONOUS

ST_ASYNC ST_DEFEXPORTED ST_EXKERB ST_EXNORESPORT ST_EXPORTANON ST_EXPORTED ST_EXPUBLIC ST_EXRDONLY ST_LOCAL ST_LOG ST_NOCOREDUMP ST_NODEVMTIME ST_QUOTA ST_ROOTFS ST_SYMPERM ST_UNION

UTIME_NOW UTIME_OMIT

_CS_GNU_LIBC_VERSION _CS_GNU_LIBPTHREAD_VERSION _CS_LFS64_CFLAGS _CS_LFS64_LDFLAGS _CS_LFS64_LIBS _CS_LFS64_LINTFLAGS _CS_LFS_CFLAGS _CS_LFS_LDFLAGS _CS_LFS_LIBS _CS_LFS_LINTFLAGS _CS_PATH _CS_POSIX_V5_WIDTH_RESTRICTED_ENVS _CS_POSIX_V6_ILP32_OFF32_CFLAGS _CS_POSIX_V6_ILP32_OFF32_LDFLAGS _CS_POSIX_V6_ILP32_OFF32_LIBS _CS_POSIX_V6_ILP32_OFF32_LINTFLAGS _CS_POSIX_V6_ILP32_OFFBIG_CFLAGS _CS_POSIX_V6_ILP32_OFFBIG_LDFLAGS _CS_POSIX_V6_ILP32_OFFBIG_LIBS _CS_POSIX_V6_ILP32_OFFBIG_LINTFLAGS _CS_POSIX_V6_LP64_OFF64_CFLAGS _CS_POSIX_V6_LP64_OFF64_LDFLAGS _CS_POSIX_V6_LP64_OFF64_LIBS _CS_POSIX_V6_LP64_OFF64_LINTFLAGS _CS_POSIX_V6_LPBIG_OFFBIG_CFLAGS _CS_POSIX_V6_LPBIG_OFFBIG_LDFLAGS _CS_POSIX_V6_LPBIG_OFFBIG_LIBS _CS_POSIX_V6_LPBIG_OFFBIG_LINTFLAGS _CS_POSIX_V6_WIDTH_RESTRICTED_ENVS _CS_POSIX_V7_ILP32_OFF32_CFLAGS _CS_POSIX_V7_ILP32_OFF32_LDFLAGS _CS_POSIX_V7_ILP32_OFF32_LIBS _CS_POSIX_V7_ILP32_OFF32_LINTFLAGS _CS_POSIX_V7_ILP32_OFFBIG_CFLAGS _CS_POSIX_V7_ILP32_OFFBIG_LDFLAGS _CS_POSIX_V7_ILP32_OFFBIG_LIBS _CS_POSIX_V7_ILP32_OFFBIG_LINTFLAGS _CS_POSIX_V7_LP64_OFF64_CFLAGS _CS_POSIX_V7_LP64_OFF64_LDFLAGS _CS_POSIX_V7_LP64_OFF64_LIBS _CS_POSIX_V7_LP64_OFF64_LINTFLAGS _CS_POSIX_V7_LPBIG_OFFBIG_CFLAGS _CS_POSIX_V7_LPBIG_OFFBIG_LDFLAGS _CS_POSIX_V7_LPBIG_OFFBIG_LIBS _CS_POSIX_V7_LPBIG_OFFBIG_LINTFLAGS _CS_POSIX_V7_WIDTH_RESTRICTED_ENVS _CS_V5_WIDTH_RESTRICTED_ENVS _CS_V6_ENV _CS_V6_WIDTH_RESTRICTED_ENVS _CS_V7_ENV _CS_V7_WIDTH_RESTRICTED_ENVS _CS_XBS5_ILP32_OFF32_CFLAGS _CS_XBS5_ILP32_OFF32_LDFLAGS _CS_XBS5_ILP32_OFF32_LIBS _CS_XBS5_ILP32_OFF32_LINTFLAGS _CS_XBS5_ILP32_OFFBIG_CFLAGS _CS_XBS5_ILP32_OFFBIG_LDFLAGS _CS_XBS5_ILP32_OFFBIG_LIBS _CS_XBS5_ILP32_OFFBIG_LINTFLAGS _CS_XBS5_LP64_OFF64_CFLAGS _CS_XBS5_LP64_OFF64_LDFLAGS _CS_XBS5_LP64_OFF64_LIBS _CS_XBS5_LP64_OFF64_LINTFLAGS _CS_XBS5_LPBIG_OFFBIG_CFLAGS _CS_XBS5_LPBIG_OFFBIG_LDFLAGS _CS_XBS5_LPBIG_OFFBIG_LIBS _CS_XBS5_LPBIG_OFFBIG_LINTFLAGS

_PC_2_SYMLINKS _PC_ALLOC_SIZE_MIN _PC_ASYNC_IO _PC_CHOWN_RESTRICTED _PC_FILESIZEBITS _PC_LINK_MAX _PC_MAX_CANON _PC_MAX_INPUT _PC_NAME_MAX _PC_NO_TRUNC _PC_PATH_MAX _PC_PIPE_BUF _PC_PRIO_IO _PC_REC_INCR_XFER_SIZE _PC_REC_MAX_XFER_SIZE _PC_REC_MIN_XFER_SIZE _PC_REC_XFER_ALIGN _PC_SOCK_MAXBUF _PC_SYMLINK_MAX _PC_SYNC_IO _PC_VDISABLE

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NOTES

removeat() is a home-grown nonstandard extension present only in this module.

preadv() and pwritev() are nonstandard extensions present in Linux and BSD.

execveat(), openat2(), preadv2(), pwritev2() and renameat2() are nonstandard extensions present in Linux.

fstatat(), lstat() and stat() do not set the special underscore filehandle _ (mostly because I have no clue how that works).

open(), openat() and openat2() do not set the O_CLOEXEC flag automatically. You have to take care of that yourself if needed.

isalnum() and friends were cowardly removed from the POSIX module with Perl 5.24.0. They have found a cozy home here with a fix for a long-standing bug.

SEEK_DATA and SEEK_HOLE were added to unistd.h in POSIX.1-2024 (Issue 8). Before that, they were nonstandard extensions present in Linux, Solaris, FreeBSD, and DragonFly BSD.

For some inexplicable reason, Perl forbids you to use the built-in chmod() and chown() on an opendir() handle and to use readdir() and rewinddir() on a sysopen() handle (provided it refers to a directory). Needless to say that chmod() and chown() from POSIX::2008 happily work with opendir() handles, and of course you can use readdir() and rewinddir() on an openat() handle that refers to a directory.

AUTHOR

Initially hacked together by Carsten Gaebler.

LICENSE

This library is free software. You can redistribute and/or modify it under the terms of the Do What The Fuck You Want To Public License, Version 2, as published by Sam Hocevar. See the COPYING file or http://www.wtfpl.net/ for more details.

cpanm POSIX::2008

perl -MCPAN -e shell
install POSIX::2008