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authorSiep Kroonenberg <siepo@cybercomm.nl>2011-02-17 16:52:23 +0000
committerSiep Kroonenberg <siepo@cybercomm.nl>2011-02-17 16:52:23 +0000
commit8da2d23733595367fad869e5fbc6c9a87041879b (patch)
tree0f3719f4eea97f872b6347c6d9ff5aa2ccd38299 /Master/tlpkg/tlperl/lib/POSIX.pod
parent9d55a4cf517a832c74e85179eac4239f9be8d2e7 (diff)
New tlperl part VIII
git-svn-id: svn://tug.org/texlive/trunk@21430 c570f23f-e606-0410-a88d-b1316a301751
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+=head1 NAME
+
+POSIX - Perl interface to IEEE Std 1003.1
+
+=head1 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
+
+=head1 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.
+
+I<Everything is exported by default> with the exception of any POSIX
+functions with the same name as a built-in Perl function, such as
+C<abs>, C<alarm>, C<rmdir>, C<write>, etc.., which will be exported
+only if you ask for them explicitly. This is an unfortunate backwards
+compatibility feature. You can stop the exporting by saying C<use
+POSIX ()> and then use the fully qualified names (ie. C<POSIX::SEEK_END>).
+
+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 L<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.
+
+=head1 NOTE
+
+The POSIX module is probably the most complex Perl module supplied with
+the standard distribution. It incorporates autoloading, namespace games,
+and dynamic loading of code that's in Perl, C, or both. It's a great
+source of wisdom.
+
+=head1 CAVEATS
+
+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.
+
+=head1 FUNCTIONS
+
+=over 8
+
+=item _exit
+
+This is identical to the C function C<_exit()>. It exits the program
+immediately which means among other things buffered I/O is B<not> flushed.
+
+Note that when using threads and in Linux this is B<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.
+
+=item abort
+
+This is identical to the C function C<abort()>. It terminates the
+process with a C<SIGABRT> signal unless caught by a signal handler or
+if the handler does not return normally (it e.g. does a C<longjmp>).
+
+=item abs
+
+This is identical to Perl's builtin C<abs()> function, returning
+the absolute value of its numerical argument.
+
+=item access
+
+Determines the accessibility of a file.
+
+ if( POSIX::access( "/", &POSIX::R_OK ) ){
+ print "have read permission\n";
+ }
+
+Returns C<undef> on failure. Note: do not use C<access()> for
+security purposes. Between the C<access()> call and the operation
+you are preparing for the permissions might change: a classic
+I<race condition>.
+
+=item acos
+
+This is identical to the C function C<acos()>, returning
+the arcus cosine of its numerical argument. See also L<Math::Trig>.
+
+=item alarm
+
+This is identical to Perl's builtin C<alarm()> function,
+either for arming or disarming the C<SIGARLM> timer.
+
+=item asctime
+
+This is identical to the C function C<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, $isdst);
+
+The C<$mon> is zero-based: January equals C<0>. The C<$year> is
+1900-based: 2001 equals C<101>. C<$wday> and C<$yday> default to zero
+(and are usually ignored anyway), and C<$isdst> defaults to -1.
+
+=item asin
+
+This is identical to the C function C<asin()>, returning
+the arcus sine of its numerical argument. See also L<Math::Trig>.
+
+=item assert
+
+Unimplemented, but you can use L<perlfunc/die> and the L<Carp> module
+to achieve similar things.
+
+=item atan
+
+This is identical to the C function C<atan()>, returning the
+arcus tangent of its numerical argument. See also L<Math::Trig>.
+
+=item atan2
+
+This is identical to Perl's builtin C<atan2()> function, returning
+the arcus tangent defined by its two numerical arguments, the I<y>
+coordinate and the I<x> coordinate. See also L<Math::Trig>.
+
+=item atexit
+
+atexit() is C-specific: use C<END {}> instead, see L<perlsub>.
+
+=item atof
+
+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.
+
+=item atoi
+
+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 L<perlfunc/int>.
+
+=item atol
+
+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 L<perlfunc/int>.
+
+=item bsearch
+
+bsearch() not supplied. For doing binary search on wordlists,
+see L<Search::Dict>.
+
+=item calloc
+
+calloc() is C-specific. Perl does memory management transparently.
+
+=item ceil
+
+This is identical to the C function C<ceil()>, returning the smallest
+integer value greater than or equal to the given numerical argument.
+
+=item chdir
+
+This is identical to Perl's builtin C<chdir()> function, allowing
+one to change the working (default) directory, see L<perlfunc/chdir>.
+
+=item chmod
+
+This is identical to Perl's builtin C<chmod()> function, allowing
+one to change file and directory permissions, see L<perlfunc/chmod>.
+
+=item chown
+
+This is identical to Perl's builtin C<chown()> function, allowing one
+to change file and directory owners and groups, see L<perlfunc/chown>.
+
+=item clearerr
+
+Use the method C<IO::Handle::clearerr()> instead, to reset the error
+state (if any) and EOF state (if any) of the given stream.
+
+=item clock
+
+This is identical to the C function C<clock()>, returning the
+amount of spent processor time in microseconds.
+
+=item close
+
+Close the file. This uses file descriptors such as those obtained by calling
+C<POSIX::open>.
+
+ $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
+ POSIX::close( $fd );
+
+Returns C<undef> on failure.
+
+See also L<perlfunc/close>.
+
+=item closedir
+
+This is identical to Perl's builtin C<closedir()> function for closing
+a directory handle, see L<perlfunc/closedir>.
+
+=item cos
+
+This is identical to Perl's builtin C<cos()> function, for returning
+the cosine of its numerical argument, see L<perlfunc/cos>.
+See also L<Math::Trig>.
+
+=item cosh
+
+This is identical to the C function C<cosh()>, for returning
+the hyperbolic cosine of its numeric argument. See also L<Math::Trig>.
+
+=item creat
+
+Create a new file. This returns a file descriptor like the ones returned by
+C<POSIX::open>. Use C<POSIX::close> to close the file.
+
+ $fd = POSIX::creat( "foo", 0611 );
+ POSIX::close( $fd );
+
+See also L<perlfunc/sysopen> and its C<O_CREAT> flag.
+
+=item ctermid
+
+Generates the path name for the controlling terminal.
+
+ $path = POSIX::ctermid();
+
+=item ctime
+
+This is identical to the C function C<ctime()> and equivalent
+to C<asctime(localtime(...))>, see L</asctime> and L</localtime>.
+
+=item cuserid
+
+Get the login name of the owner of the current process.
+
+ $name = POSIX::cuserid();
+
+=item difftime
+
+This is identical to the C function C<difftime()>, for returning
+the time difference (in seconds) between two times (as returned
+by C<time()>), see L</time>.
+
+=item div
+
+div() is C-specific, use L<perlfunc/int> on the usual C</> division and
+the modulus C<%>.
+
+=item dup
+
+This is similar to the C function C<dup()>, for duplicating a file
+descriptor.
+
+This uses file descriptors such as those obtained by calling
+C<POSIX::open>.
+
+Returns C<undef> on failure.
+
+=item dup2
+
+This is similar to the C function C<dup2()>, for duplicating a file
+descriptor to an another known file descriptor.
+
+This uses file descriptors such as those obtained by calling
+C<POSIX::open>.
+
+Returns C<undef> on failure.
+
+=item errno
+
+Returns the value of errno.
+
+ $errno = POSIX::errno();
+
+This identical to the numerical values of the C<$!>, see L<perlvar/$ERRNO>.
+
+=item execl
+
+execl() is C-specific, see L<perlfunc/exec>.
+
+=item execle
+
+execle() is C-specific, see L<perlfunc/exec>.
+
+=item execlp
+
+execlp() is C-specific, see L<perlfunc/exec>.
+
+=item execv
+
+execv() is C-specific, see L<perlfunc/exec>.
+
+=item execve
+
+execve() is C-specific, see L<perlfunc/exec>.
+
+=item execvp
+
+execvp() is C-specific, see L<perlfunc/exec>.
+
+=item exit
+
+This is identical to Perl's builtin C<exit()> function for exiting the
+program, see L<perlfunc/exit>.
+
+=item exp
+
+This is identical to Perl's builtin C<exp()> function for
+returning the exponent (I<e>-based) of the numerical argument,
+see L<perlfunc/exp>.
+
+=item fabs
+
+This is identical to Perl's builtin C<abs()> function for returning
+the absolute value of the numerical argument, see L<perlfunc/abs>.
+
+=item fclose
+
+Use method C<IO::Handle::close()> instead, or see L<perlfunc/close>.
+
+=item fcntl
+
+This is identical to Perl's builtin C<fcntl()> function,
+see L<perlfunc/fcntl>.
+
+=item fdopen
+
+Use method C<IO::Handle::new_from_fd()> instead, or see L<perlfunc/open>.
+
+=item feof
+
+Use method C<IO::Handle::eof()> instead, or see L<perlfunc/eof>.
+
+=item ferror
+
+Use method C<IO::Handle::error()> instead.
+
+=item fflush
+
+Use method C<IO::Handle::flush()> instead.
+See also L<perlvar/$OUTPUT_AUTOFLUSH>.
+
+=item fgetc
+
+Use method C<IO::Handle::getc()> instead, or see L<perlfunc/read>.
+
+=item fgetpos
+
+Use method C<IO::Seekable::getpos()> instead, or see L<L/seek>.
+
+=item fgets
+
+Use method C<IO::Handle::gets()> instead. Similar to E<lt>E<gt>, also known
+as L<perlfunc/readline>.
+
+=item fileno
+
+Use method C<IO::Handle::fileno()> instead, or see L<perlfunc/fileno>.
+
+=item floor
+
+This is identical to the C function C<floor()>, returning the largest
+integer value less than or equal to the numerical argument.
+
+=item fmod
+
+This is identical to the C function C<fmod()>.
+
+ $r = fmod($x, $y);
+
+It returns the remainder C<$r = $x - $n*$y>, where C<$n = trunc($x/$y)>.
+The C<$r> has the same sign as C<$x> and magnitude (absolute value)
+less than the magnitude of C<$y>.
+
+=item fopen
+
+Use method C<IO::File::open()> instead, or see L<perlfunc/open>.
+
+=item fork
+
+This is identical to Perl's builtin C<fork()> function
+for duplicating the current process, see L<perlfunc/fork>
+and L<perlfork> if you are in Windows.
+
+=item fpathconf
+
+Retrieves the value of a configurable limit on a file or directory. This
+uses file descriptors such as those obtained by calling C<POSIX::open>.
+
+The following will determine the maximum length of the longest allowable
+pathname on the filesystem which holds C</var/foo>.
+
+ $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
+ $path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );
+
+Returns C<undef> on failure.
+
+=item fprintf
+
+fprintf() is C-specific, see L<perlfunc/printf> instead.
+
+=item fputc
+
+fputc() is C-specific, see L<perlfunc/print> instead.
+
+=item fputs
+
+fputs() is C-specific, see L<perlfunc/print> instead.
+
+=item fread
+
+fread() is C-specific, see L<perlfunc/read> instead.
+
+=item free
+
+free() is C-specific. Perl does memory management transparently.
+
+=item freopen
+
+freopen() is C-specific, see L<perlfunc/open> instead.
+
+=item frexp
+
+Return the mantissa and exponent of a floating-point number.
+
+ ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
+
+=item fscanf
+
+fscanf() is C-specific, use E<lt>E<gt> and regular expressions instead.
+
+=item fseek
+
+Use method C<IO::Seekable::seek()> instead, or see L<perlfunc/seek>.
+
+=item fsetpos
+
+Use method C<IO::Seekable::setpos()> instead, or seek L<perlfunc/seek>.
+
+=item fstat
+
+Get file status. This uses file descriptors such as those obtained by
+calling C<POSIX::open>. The data returned is identical to the data from
+Perl's builtin C<stat> function.
+
+ $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
+ @stats = POSIX::fstat( $fd );
+
+=item fsync
+
+Use method C<IO::Handle::sync()> instead.
+
+=item ftell
+
+Use method C<IO::Seekable::tell()> instead, or see L<perlfunc/tell>.
+
+=item fwrite
+
+fwrite() is C-specific, see L<perlfunc/print> instead.
+
+=item getc
+
+This is identical to Perl's builtin C<getc()> function,
+see L<perlfunc/getc>.
+
+=item getchar
+
+Returns one character from STDIN. Identical to Perl's C<getc()>,
+see L<perlfunc/getc>.
+
+=item getcwd
+
+Returns the name of the current working directory.
+See also L<Cwd>.
+
+=item getegid
+
+Returns the effective group identifier. Similar to Perl' s builtin
+variable C<$(>, see L<perlvar/$EGID>.
+
+=item getenv
+
+Returns the value of the specified environment variable.
+The same information is available through the C<%ENV> array.
+
+=item geteuid
+
+Returns the effective user identifier. Identical to Perl's builtin C<$E<gt>>
+variable, see L<perlvar/$EUID>.
+
+=item getgid
+
+Returns the user's real group identifier. Similar to Perl's builtin
+variable C<$)>, see L<perlvar/$GID>.
+
+=item getgrgid
+
+This is identical to Perl's builtin C<getgrgid()> function for
+returning group entries by group identifiers, see
+L<perlfunc/getgrgid>.
+
+=item getgrnam
+
+This is identical to Perl's builtin C<getgrnam()> function for
+returning group entries by group names, see L<perlfunc/getgrnam>.
+
+=item getgroups
+
+Returns the ids of the user's supplementary groups. Similar to Perl's
+builtin variable C<$)>, see L<perlvar/$GID>.
+
+=item getlogin
+
+This is identical to Perl's builtin C<getlogin()> function for
+returning the user name associated with the current session, see
+L<perlfunc/getlogin>.
+
+=item getpgrp
+
+This is identical to Perl's builtin C<getpgrp()> function for
+returning the process group identifier of the current process, see
+L<perlfunc/getpgrp>.
+
+=item getpid
+
+Returns the process identifier. Identical to Perl's builtin
+variable C<$$>, see L<perlvar/$PID>.
+
+=item getppid
+
+This is identical to Perl's builtin C<getppid()> function for
+returning the process identifier of the parent process of the current
+process , see L<perlfunc/getppid>.
+
+=item getpwnam
+
+This is identical to Perl's builtin C<getpwnam()> function for
+returning user entries by user names, see L<perlfunc/getpwnam>.
+
+=item getpwuid
+
+This is identical to Perl's builtin C<getpwuid()> function for
+returning user entries by user identifiers, see L<perlfunc/getpwuid>.
+
+=item gets
+
+Returns one line from C<STDIN>, similar to E<lt>E<gt>, also known
+as the C<readline()> function, see L<perlfunc/readline>.
+
+B<NOTE>: if you have C programs that still use C<gets()>, be very
+afraid. The C<gets()> function is a source of endless grief because
+it has no buffer overrun checks. It should B<never> be used. The
+C<fgets()> function should be preferred instead.
+
+=item getuid
+
+Returns the user's identifier. Identical to Perl's builtin C<$E<lt>> variable,
+see L<perlvar/$UID>.
+
+=item gmtime
+
+This is identical to Perl's builtin C<gmtime()> function for
+converting seconds since the epoch to a date in Greenwich Mean Time,
+see L<perlfunc/gmtime>.
+
+=item isalnum
+
+This is identical to the C function, except that it can apply to a
+single character or to a whole string. Note that locale settings may
+affect what characters are considered C<isalnum>. Does not work on
+Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:alnum:]]/> construct instead, or possibly
+the C</\w/> construct.
+
+=item isalpha
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<isalpha>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:alpha:]]/> construct instead.
+
+=item isatty
+
+Returns a boolean indicating whether the specified filehandle is connected
+to a tty. Similar to the C<-t> operator, see L<perlfunc/-X>.
+
+=item iscntrl
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<iscntrl>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:cntrl:]]/> construct instead.
+
+=item isdigit
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<isdigit> (unlikely, but
+still possible). Does not work on Unicode characters code point 256
+or higher. Consider using regular expressions and the C</[[:digit:]]/>
+construct instead, or the C</\d/> construct.
+
+=item isgraph
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<isgraph>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:graph:]]/> construct instead.
+
+=item islower
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<islower>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:lower:]]/> construct instead. Do B<not> use
+C</[a-z]/>.
+
+=item isprint
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<isprint>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:print:]]/> construct instead.
+
+=item ispunct
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<ispunct>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:punct:]]/> construct instead.
+
+=item isspace
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<isspace>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:space:]]/> construct instead, or the C</\s/>
+construct. (Note that C</\s/> and C</[[:space:]]/> are slightly
+different in that C</[[:space:]]/> can normally match a vertical tab,
+while C</\s/> does not.)
+
+=item isupper
+
+This is identical to the C function, except that it can apply to
+a single character or to a whole string. Note that locale settings
+may affect what characters are considered C<isupper>. Does not work
+on Unicode characters code point 256 or higher. Consider using regular
+expressions and the C</[[:upper:]]/> construct instead. Do B<not> use
+C</[A-Z]/>.
+
+=item isxdigit
+
+This is identical to the C function, except that it can apply to a single
+character or to a whole string. Note that locale settings may affect what
+characters are considered C<isxdigit> (unlikely, but still possible).
+Does not work on Unicode characters code point 256 or higher.
+Consider using regular expressions and the C</[[:xdigit:]]/>
+construct instead, or simply C</[0-9a-f]/i>.
+
+=item kill
+
+This is identical to Perl's builtin C<kill()> function for sending
+signals to processes (often to terminate them), see L<perlfunc/kill>.
+
+=item labs
+
+(For returning absolute values of long integers.)
+labs() is C-specific, see L<perlfunc/abs> instead.
+
+=item lchown
+
+This is identical to the C function, except the order of arguments is
+consistent with Perl's builtin C<chown()> with the added restriction
+of only one path, not an list of paths. Does the same thing as the
+C<chown()> function but changes the owner of a symbolic link instead
+of the file the symbolic link points to.
+
+=item ldexp
+
+This is identical to the C function C<ldexp()>
+for multiplying floating point numbers with powers of two.
+
+ $x_quadrupled = POSIX::ldexp($x, 2);
+
+=item ldiv
+
+(For computing dividends of long integers.)
+ldiv() is C-specific, use C</> and C<int()> instead.
+
+=item link
+
+This is identical to Perl's builtin C<link()> function
+for creating hard links into files, see L<perlfunc/link>.
+
+=item localeconv
+
+Get numeric formatting information. Returns a reference to a hash
+containing the current locale formatting values.
+
+Here is how to query the database for the B<de> (Deutsch or German) locale.
+
+ $loc = POSIX::setlocale( &POSIX::LC_ALL, "de" );
+ print "Locale = $loc\n";
+ $lconv = POSIX::localeconv();
+ print "decimal_point = ", $lconv->{decimal_point}, "\n";
+ print "thousands_sep = ", $lconv->{thousands_sep}, "\n";
+ print "grouping = ", $lconv->{grouping}, "\n";
+ print "int_curr_symbol = ", $lconv->{int_curr_symbol}, "\n";
+ print "currency_symbol = ", $lconv->{currency_symbol}, "\n";
+ print "mon_decimal_point = ", $lconv->{mon_decimal_point}, "\n";
+ print "mon_thousands_sep = ", $lconv->{mon_thousands_sep}, "\n";
+ print "mon_grouping = ", $lconv->{mon_grouping}, "\n";
+ print "positive_sign = ", $lconv->{positive_sign}, "\n";
+ print "negative_sign = ", $lconv->{negative_sign}, "\n";
+ print "int_frac_digits = ", $lconv->{int_frac_digits}, "\n";
+ print "frac_digits = ", $lconv->{frac_digits}, "\n";
+ print "p_cs_precedes = ", $lconv->{p_cs_precedes}, "\n";
+ print "p_sep_by_space = ", $lconv->{p_sep_by_space}, "\n";
+ print "n_cs_precedes = ", $lconv->{n_cs_precedes}, "\n";
+ print "n_sep_by_space = ", $lconv->{n_sep_by_space}, "\n";
+ print "p_sign_posn = ", $lconv->{p_sign_posn}, "\n";
+ print "n_sign_posn = ", $lconv->{n_sign_posn}, "\n";
+
+=item localtime
+
+This is identical to Perl's builtin C<localtime()> function for
+converting seconds since the epoch to a date see L<perlfunc/localtime>.
+
+=item log
+
+This is identical to Perl's builtin C<log()> function,
+returning the natural (I<e>-based) logarithm of the numerical argument,
+see L<perlfunc/log>.
+
+=item log10
+
+This is identical to the C function C<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 }
+
+=item longjmp
+
+longjmp() is C-specific: use L<perlfunc/die> instead.
+
+=item lseek
+
+Move the file's read/write position. This uses file descriptors such as
+those obtained by calling C<POSIX::open>.
+
+ $fd = POSIX::open( "foo", &POSIX::O_RDONLY );
+ $off_t = POSIX::lseek( $fd, 0, &POSIX::SEEK_SET );
+
+Returns C<undef> on failure.
+
+=item malloc
+
+malloc() is C-specific. Perl does memory management transparently.
+
+=item mblen
+
+This is identical to the C function C<mblen()>.
+Perl does not have any support for the wide and multibyte
+characters of the C standards, so this might be a rather
+useless function.
+
+=item mbstowcs
+
+This is identical to the C function C<mbstowcs()>.
+Perl does not have any support for the wide and multibyte
+characters of the C standards, so this might be a rather
+useless function.
+
+=item mbtowc
+
+This is identical to the C function C<mbtowc()>.
+Perl does not have any support for the wide and multibyte
+characters of the C standards, so this might be a rather
+useless function.
+
+=item memchr
+
+memchr() is C-specific, see L<perlfunc/index> instead.
+
+=item memcmp
+
+memcmp() is C-specific, use C<eq> instead, see L<perlop>.
+
+=item memcpy
+
+memcpy() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
+
+=item memmove
+
+memmove() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
+
+=item memset
+
+memset() is C-specific, use C<x> instead, see L<perlop>.
+
+=item mkdir
+
+This is identical to Perl's builtin C<mkdir()> function
+for creating directories, see L<perlfunc/mkdir>.
+
+=item mkfifo
+
+This is similar to the C function C<mkfifo()> for creating
+FIFO special files.
+
+ if (mkfifo($path, $mode)) { ....
+
+Returns C<undef> on failure. The C<$mode> is similar to the
+mode of C<mkdir()>, see L<perlfunc/mkdir>, though for C<mkfifo>
+you B<must> specify the C<$mode>.
+
+=item 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 (C<mon>), weekday (C<wday>), and yearday (C<yday>) begin at zero.
+I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
+year (C<year>) is given in years since 1900. I.e. The year 1995 is 95; the
+year 2001 is 101. Consult your system's C<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 C<undef> on failure.
+
+=item modf
+
+Return the integral and fractional parts of a floating-point number.
+
+ ($fractional, $integral) = POSIX::modf( 3.14 );
+
+=item nice
+
+This is similar to the C function C<nice()>, for changing
+the scheduling preference of the current process. Positive
+arguments mean more polite process, negative values more
+needy process. Normal user processes can only be more polite.
+
+Returns C<undef> on failure.
+
+=item offsetof
+
+offsetof() is C-specific, you probably want to see L<perlfunc/pack> instead.
+
+=item open
+
+Open a file for reading for writing. This returns file descriptors, not
+Perl filehandles. Use C<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 C<undef> on failure.
+
+See also L<perlfunc/sysopen>.
+
+=item opendir
+
+Open a directory for reading.
+
+ $dir = POSIX::opendir( "/var" );
+ @files = POSIX::readdir( $dir );
+ POSIX::closedir( $dir );
+
+Returns C<undef> on failure.
+
+=item 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 C</var>.
+
+ $path_max = POSIX::pathconf( "/var", &POSIX::_PC_PATH_MAX );
+
+Returns C<undef> on failure.
+
+=item pause
+
+This is similar to the C function C<pause()>, which suspends
+the execution of the current process until a signal is received.
+
+Returns C<undef> on failure.
+
+=item perror
+
+This is identical to the C function C<perror()>, which outputs to the
+standard error stream the specified message followed by ": " and the
+current error string. Use the C<warn()> function and the C<$!>
+variable instead, see L<perlfunc/warn> and L<perlvar/$ERRNO>.
+
+=item pipe
+
+Create an interprocess channel. This returns file descriptors like those
+returned by C<POSIX::open>.
+
+ my ($read, $write) = POSIX::pipe();
+ POSIX::write( $write, "hello", 5 );
+ POSIX::read( $read, $buf, 5 );
+
+See also L<perlfunc/pipe>.
+
+=item pow
+
+Computes C<$x> raised to the power C<$exponent>.
+
+ $ret = POSIX::pow( $x, $exponent );
+
+You can also use the C<**> operator, see L<perlop>.
+
+=item printf
+
+Formats and prints the specified arguments to STDOUT.
+See also L<perlfunc/printf>.
+
+=item putc
+
+putc() is C-specific, see L<perlfunc/print> instead.
+
+=item putchar
+
+putchar() is C-specific, see L<perlfunc/print> instead.
+
+=item puts
+
+puts() is C-specific, see L<perlfunc/print> instead.
+
+=item qsort
+
+qsort() is C-specific, see L<perlfunc/sort> instead.
+
+=item raise
+
+Sends the specified signal to the current process.
+See also L<perlfunc/kill> and the C<$$> in L<perlvar/$PID>.
+
+=item rand
+
+C<rand()> is non-portable, see L<perlfunc/rand> instead.
+
+=item read
+
+Read from a file. This uses file descriptors such as those obtained by
+calling C<POSIX::open>. If the buffer C<$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, $buf, 3 );
+
+Returns C<undef> on failure.
+
+See also L<perlfunc/sysread>.
+
+=item readdir
+
+This is identical to Perl's builtin C<readdir()> function
+for reading directory entries, see L<perlfunc/readdir>.
+
+=item realloc
+
+realloc() is C-specific. Perl does memory management transparently.
+
+=item remove
+
+This is identical to Perl's builtin C<unlink()> function
+for removing files, see L<perlfunc/unlink>.
+
+=item rename
+
+This is identical to Perl's builtin C<rename()> function
+for renaming files, see L<perlfunc/rename>.
+
+=item rewind
+
+Seeks to the beginning of the file.
+
+=item rewinddir
+
+This is identical to Perl's builtin C<rewinddir()> function for
+rewinding directory entry streams, see L<perlfunc/rewinddir>.
+
+=item rmdir
+
+This is identical to Perl's builtin C<rmdir()> function
+for removing (empty) directories, see L<perlfunc/rmdir>.
+
+=item scanf
+
+scanf() is C-specific, use E<lt>E<gt> and regular expressions instead,
+see L<perlre>.
+
+=item setgid
+
+Sets the real group identifier and the effective group identifier for
+this process. Similar to assigning a value to the Perl's builtin
+C<$)> variable, see L<perlvar/$EGID>, except that the latter
+will change only the real user identifier, and that the setgid()
+uses only a single numeric argument, as opposed to a space-separated
+list of numbers.
+
+=item setjmp
+
+C<setjmp()> is C-specific: use C<eval {}> instead,
+see L<perlfunc/eval>.
+
+=item setlocale
+
+Modifies and queries program's locale. The following examples assume
+
+ use POSIX qw(setlocale LC_ALL LC_CTYPE);
+
+has been issued.
+
+The following will set the traditional UNIX system locale behavior
+(the second argument C<"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 C<"">).
+Please see your systems C<setlocale(3)> documentation for the locale
+environment variables' meaning or consult L<perllocale>.
+
+ $loc = setlocale( LC_CTYPE, "" );
+
+The following will set the LC_COLLATE behaviour to Argentinian
+Spanish. B<NOTE>: The naming and availability of locales depends on
+your operating system. Please consult L<perllocale> for how to find
+out which locales are available in your system.
+
+ $loc = setlocale( LC_COLLATE, "es_AR.ISO8859-1" );
+
+=item setpgid
+
+This is similar to the C function C<setpgid()> for
+setting the process group identifier of the current process.
+
+Returns C<undef> on failure.
+
+=item setsid
+
+This is identical to the C function C<setsid()> for
+setting the session identifier of the current process.
+
+=item setuid
+
+Sets the real user identifier and the effective user identifier for
+this process. Similar to assigning a value to the Perl's builtin
+C<$E<lt>> variable, see L<perlvar/$UID>, except that the latter
+will change only the real user identifier.
+
+=item sigaction
+
+Detailed signal management. This uses C<POSIX::SigAction> objects for
+the C<action> and C<oldaction> arguments (the oldaction can also be
+just a hash reference). Consult your system's C<sigaction> manpage
+for details, see also C<POSIX::SigRt>.
+
+Synopsis:
+
+ sigaction(signal, action, oldaction = 0)
+
+Returns C<undef> on failure. The C<signal> must be a number (like
+SIGHUP), not a string (like "SIGHUP"), though Perl does try hard
+to understand you.
+
+If you use the SA_SIGINFO flag, the signal handler will in addition to
+the first argument, the signal name, also receive a second argument, a
+hash reference, inside which are the following keys with the following
+semantics, as defined by POSIX/SUSv3:
+
+ signo the signal number
+ errno the error number
+ code if this is zero or less, the signal was sent by
+ a user process and the uid and pid make sense,
+ otherwise the signal was sent by the kernel
+
+The following are also defined by POSIX/SUSv3, but unfortunately
+not very widely implemented:
+
+ pid the process id generating the signal
+ uid the uid of the process id generating the signal
+ status exit value or signal for SIGCHLD
+ band band event for SIGPOLL
+
+A third argument is also passed to the handler, which contains a copy
+of the raw binary contents of the siginfo structure: if a system has
+some non-POSIX fields, this third argument is where to unpack() them
+from.
+
+Note that not all siginfo values make sense simultaneously (some are
+valid only for certain signals, for example), and not all values make
+sense from Perl perspective, you should to consult your system's
+C<sigaction> and possibly also C<siginfo> documentation.
+
+=item siglongjmp
+
+siglongjmp() is C-specific: use L<perlfunc/die> instead.
+
+=item sigpending
+
+Examine signals that are blocked and pending. This uses C<POSIX::SigSet>
+objects for the C<sigset> argument. Consult your system's C<sigpending>
+manpage for details.
+
+Synopsis:
+
+ sigpending(sigset)
+
+Returns C<undef> on failure.
+
+=item sigprocmask
+
+Change and/or examine calling process's signal mask. This uses
+C<POSIX::SigSet> objects for the C<sigset> and C<oldsigset> arguments.
+Consult your system's C<sigprocmask> manpage for details.
+
+Synopsis:
+
+ sigprocmask(how, sigset, oldsigset = 0)
+
+Returns C<undef> on failure.
+
+=item sigsetjmp
+
+C<sigsetjmp()> is C-specific: use C<eval {}> instead,
+see L<perlfunc/eval>.
+
+=item sigsuspend
+
+Install a signal mask and suspend process until signal arrives. This uses
+C<POSIX::SigSet> objects for the C<signal_mask> argument. Consult your
+system's C<sigsuspend> manpage for details.
+
+Synopsis:
+
+ sigsuspend(signal_mask)
+
+Returns C<undef> on failure.
+
+=item sin
+
+This is identical to Perl's builtin C<sin()> function
+for returning the sine of the numerical argument,
+see L<perlfunc/sin>. See also L<Math::Trig>.
+
+=item sinh
+
+This is identical to the C function C<sinh()>
+for returning the hyperbolic sine of the numerical argument.
+See also L<Math::Trig>.
+
+=item sleep
+
+This is functionally identical to Perl's builtin C<sleep()> function
+for suspending the execution of the current for process for certain
+number of seconds, see L<perlfunc/sleep>. There is one significant
+difference, however: C<POSIX::sleep()> returns the number of
+B<unslept> seconds, while the C<CORE::sleep()> returns the
+number of slept seconds.
+
+=item sprintf
+
+This is similar to Perl's builtin C<sprintf()> function
+for returning a string that has the arguments formatted as requested,
+see L<perlfunc/sprintf>.
+
+=item sqrt
+
+This is identical to Perl's builtin C<sqrt()> function.
+for returning the square root of the numerical argument,
+see L<perlfunc/sqrt>.
+
+=item srand
+
+Give a seed the pseudorandom number generator, see L<perlfunc/srand>.
+
+=item sscanf
+
+sscanf() is C-specific, use regular expressions instead,
+see L<perlre>.
+
+=item stat
+
+This is identical to Perl's builtin C<stat()> function
+for returning information about files and directories.
+
+=item strcat
+
+strcat() is C-specific, use C<.=> instead, see L<perlop>.
+
+=item strchr
+
+strchr() is C-specific, see L<perlfunc/index> instead.
+
+=item strcmp
+
+strcmp() is C-specific, use C<eq> or C<cmp> instead, see L<perlop>.
+
+=item strcoll
+
+This is identical to the C function C<strcoll()>
+for collating (comparing) strings transformed using
+the C<strxfrm()> function. Not really needed since
+Perl can do this transparently, see L<perllocale>.
+
+=item strcpy
+
+strcpy() is C-specific, use C<=> instead, see L<perlop>.
+
+=item strcspn
+
+strcspn() is C-specific, use regular expressions instead,
+see L<perlre>.
+
+=item strerror
+
+Returns the error string for the specified errno.
+Identical to the string form of the C<$!>, see L<perlvar/$ERRNO>.
+
+=item 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 (C<mon>), weekday (C<wday>), and yearday (C<yday>) begin at zero.
+I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
+year (C<year>) is given in years since 1900. I.e., the year 1995 is 95; the
+year 2001 is 101. Consult your system's C<strftime()> manpage for details
+about these and the other arguments.
+
+If you want your code to be portable, your format (C<fmt>) argument
+should use only the conversion specifiers defined by the ANSI C
+standard (C89, to play safe). These are C<aAbBcdHIjmMpSUwWxXyYZ%>.
+But even then, the B<results> of some of the conversion specifiers are
+non-portable. For example, the specifiers C<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<c> changes according to the timezone settings of the
+user and the timezone computation rules of the operating system.
+The C<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
+C<mktime()> before calling your system's C<strftime()> function,
+except that the C<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";
+
+=item strlen
+
+strlen() is C-specific, use C<length()> instead, see L<perlfunc/length>.
+
+=item strncat
+
+strncat() is C-specific, use C<.=> instead, see L<perlop>.
+
+=item strncmp
+
+strncmp() is C-specific, use C<eq> instead, see L<perlop>.
+
+=item strncpy
+
+strncpy() is C-specific, use C<=> instead, see L<perlop>.
+
+=item strpbrk
+
+strpbrk() is C-specific, use regular expressions instead,
+see L<perlre>.
+
+=item strrchr
+
+strrchr() is C-specific, see L<perlfunc/rindex> instead.
+
+=item strspn
+
+strspn() is C-specific, use regular expressions instead,
+see L<perlre>.
+
+=item strstr
+
+This is identical to Perl's builtin C<index()> function,
+see L<perlfunc/index>.
+
+=item 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 should respect any POSIX I<setlocale()> settings.
+
+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.
+
+=item strtok
+
+strtok() is C-specific, use regular expressions instead, see
+L<perlre>, or L<perlfunc/split>.
+
+=item 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 I<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.
+
+=item strtoul
+
+String to unsigned (long) integer translation. strtoul() is identical
+to strtol() except that strtoul() only parses unsigned integers. See
+L</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.
+
+=item strxfrm
+
+String transformation. Returns the transformed string.
+
+ $dst = POSIX::strxfrm( $src );
+
+Used in conjunction with the C<strcoll()> function, see L</strcoll>.
+
+Not really needed since Perl can do this transparently, see
+L<perllocale>.
+
+=item sysconf
+
+Retrieves values of system configurable variables.
+
+The following will get the machine's clock speed.
+
+ $clock_ticks = POSIX::sysconf( &POSIX::_SC_CLK_TCK );
+
+Returns C<undef> on failure.
+
+=item system
+
+This is identical to Perl's builtin C<system()> function, see
+L<perlfunc/system>.
+
+=item tan
+
+This is identical to the C function C<tan()>, returning the
+tangent of the numerical argument. See also L<Math::Trig>.
+
+=item tanh
+
+This is identical to the C function C<tanh()>, returning the
+hyperbolic tangent of the numerical argument. See also L<Math::Trig>.
+
+=item tcdrain
+
+This is similar to the C function C<tcdrain()> for draining
+the output queue of its argument stream.
+
+Returns C<undef> on failure.
+
+=item tcflow
+
+This is similar to the C function C<tcflow()> for controlling
+the flow of its argument stream.
+
+Returns C<undef> on failure.
+
+=item tcflush
+
+This is similar to the C function C<tcflush()> for flushing
+the I/O buffers of its argument stream.
+
+Returns C<undef> on failure.
+
+=item tcgetpgrp
+
+This is identical to the C function C<tcgetpgrp()> for returning the
+process group identifier of the foreground process group of the controlling
+terminal.
+
+=item tcsendbreak
+
+This is similar to the C function C<tcsendbreak()> for sending
+a break on its argument stream.
+
+Returns C<undef> on failure.
+
+=item tcsetpgrp
+
+This is similar to the C function C<tcsetpgrp()> for setting the
+process group identifier of the foreground process group of the controlling
+terminal.
+
+Returns C<undef> on failure.
+
+=item time
+
+This is identical to Perl's builtin C<time()> function
+for returning the number of seconds since the epoch
+(whatever it is for the system), see L<perlfunc/time>.
+
+=item times
+
+The times() function returns elapsed realtime since some point in the past
+(such as system startup), user and system times for this process, and user
+and system times used by child processes. All times are returned in clock
+ticks.
+
+ ($realtime, $user, $system, $cuser, $csystem) = POSIX::times();
+
+Note: Perl's builtin C<times()> function returns four values, measured in
+seconds.
+
+=item tmpfile
+
+Use method C<IO::File::new_tmpfile()> instead, or see L<File::Temp>.
+
+=item tmpnam
+
+Returns a name for a temporary file.
+
+ $tmpfile = POSIX::tmpnam();
+
+For security reasons, which are probably detailed in your system's
+documentation for the C library tmpnam() function, this interface
+should not be used; instead see L<File::Temp>.
+
+=item tolower
+
+This is identical to the C function, except that it can apply to a single
+character or to a whole string. Consider using the C<lc()> function,
+see L<perlfunc/lc>, or the equivalent C<\L> operator inside doublequotish
+strings.
+
+=item toupper
+
+This is identical to the C function, except that it can apply to a single
+character or to a whole string. Consider using the C<uc()> function,
+see L<perlfunc/uc>, or the equivalent C<\U> operator inside doublequotish
+strings.
+
+=item ttyname
+
+This is identical to the C function C<ttyname()> for returning the
+name of the current terminal.
+
+=item tzname
+
+Retrieves the time conversion information from the C<tzname> variable.
+
+ POSIX::tzset();
+ ($std, $dst) = POSIX::tzname();
+
+=item tzset
+
+This is identical to the C function C<tzset()> for setting
+the current timezone based on the environment variable C<TZ>,
+to be used by C<ctime()>, C<localtime()>, C<mktime()>, and C<strftime()>
+functions.
+
+=item umask
+
+This is identical to Perl's builtin C<umask()> function
+for setting (and querying) the file creation permission mask,
+see L<perlfunc/umask>.
+
+=item uname
+
+Get name of current operating system.
+
+ ($sysname, $nodename, $release, $version, $machine) = POSIX::uname();
+
+Note that the actual meanings of the various fields are not
+that well standardized, do not expect any great portability.
+The C<$sysname> might be the name of the operating system,
+the C<$nodename> might be the name of the host, the C<$release>
+might be the (major) release number of the operating system,
+the C<$version> might be the (minor) release number of the
+operating system, and the C<$machine> might be a hardware identifier.
+Maybe.
+
+=item ungetc
+
+Use method C<IO::Handle::ungetc()> instead.
+
+=item unlink
+
+This is identical to Perl's builtin C<unlink()> function
+for removing files, see L<perlfunc/unlink>.
+
+=item utime
+
+This is identical to Perl's builtin C<utime()> function
+for changing the time stamps of files and directories,
+see L<perlfunc/utime>.
+
+=item vfprintf
+
+vfprintf() is C-specific, see L<perlfunc/printf> instead.
+
+=item vprintf
+
+vprintf() is C-specific, see L<perlfunc/printf> instead.
+
+=item vsprintf
+
+vsprintf() is C-specific, see L<perlfunc/sprintf> instead.
+
+=item wait
+
+This is identical to Perl's builtin C<wait()> function,
+see L<perlfunc/wait>.
+
+=item waitpid
+
+Wait for a child process to change state. This is identical to Perl's
+builtin C<waitpid()> function, see L<perlfunc/waitpid>.
+
+ $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
+ print "status = ", ($? / 256), "\n";
+
+=item wcstombs
+
+This is identical to the C function C<wcstombs()>.
+Perl does not have any support for the wide and multibyte
+characters of the C standards, so this might be a rather
+useless function.
+
+=item wctomb
+
+This is identical to the C function C<wctomb()>.
+Perl does not have any support for the wide and multibyte
+characters of the C standards, so this might be a rather
+useless function.
+
+=item write
+
+Write to a file. This uses file descriptors such as those obtained by
+calling C<POSIX::open>.
+
+ $fd = POSIX::open( "foo", &POSIX::O_WRONLY );
+ $buf = "hello";
+ $bytes = POSIX::write( $fd, $buf, 5 );
+
+Returns C<undef> on failure.
+
+See also L<perlfunc/syswrite>.
+
+=back
+
+=head1 CLASSES
+
+=head2 POSIX::SigAction
+
+=over 8
+
+=item new
+
+Creates a new C<POSIX::SigAction> object which corresponds to the C
+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 C<POSIX::SigSet> object, it
+defaults to the empty set. The third parameter contains the
+C<sa_flags>, it defaults to 0.
+
+ $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT);
+ $sigaction = POSIX::SigAction->new( \&handler, $sigset, &POSIX::SA_NOCLDSTOP );
+
+This C<POSIX::SigAction> object is intended for use with the C<POSIX::sigaction()>
+function.
+
+=back
+
+=over 8
+
+=item handler
+
+=item mask
+
+=item flags
+
+accessor functions to get/set the values of a SigAction object.
+
+ $sigset = $sigaction->mask;
+ $sigaction->flags(&POSIX::SA_RESTART);
+
+=item safe
+
+accessor function for the "safe signals" flag of a SigAction object; see
+L<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 C<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 C<POSIX::sigaction()>:
+
+ sigaction(SIGINT, $new_action, $old_action);
+ if ($old_action->safe) {
+ # previous SIGINT handler used safe signals
+ }
+
+=back
+
+=head2 POSIX::SigRt
+
+=over 8
+
+=item %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 $SIG{SIGRTMIN}, but the right POSIX moves (see below) are made with
+the POSIX::SigSet and POSIX::sigaction instead of accessing the %SIG.
+
+You can set the %POSIX::SIGRT elements to set the POSIX realtime
+signal handlers, use C<delete> and C<exists> on the elements, and use
+C<scalar> on the C<%POSIX::SIGRT> to find out how many POSIX realtime
+signals there are available (SIGRTMAX - SIGRTMIN + 1, the SIGRTMAX is
+a valid POSIX realtime signal).
+
+Setting the %SIGRT elements is equivalent to calling this:
+
+ sub new {
+ my ($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 C<local> on $POSIX::SigRt::SIGACTION_FLAGS, or you can
+derive from POSIX::SigRt and define your own C<new()> (the tied hash
+STORE method of the %SIGRT calls C<new($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).
+
+B<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.
+
+=item SIGRTMIN
+
+Return the minimum POSIX realtime signal number available, or C<undef>
+if no POSIX realtime signals are available.
+
+=item SIGRTMAX
+
+Return the maximum POSIX realtime signal number available, or C<undef>
+if no POSIX realtime signals are available.
+
+=back
+
+=head2 POSIX::SigSet
+
+=over 8
+
+=item 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 );
+
+=item addset
+
+Add a signal to a SigSet object.
+
+ $sigset->addset( &POSIX::SIGUSR2 );
+
+Returns C<undef> on failure.
+
+=item delset
+
+Remove a signal from the SigSet object.
+
+ $sigset->delset( &POSIX::SIGUSR2 );
+
+Returns C<undef> on failure.
+
+=item emptyset
+
+Initialize the SigSet object to be empty.
+
+ $sigset->emptyset();
+
+Returns C<undef> on failure.
+
+=item fillset
+
+Initialize the SigSet object to include all signals.
+
+ $sigset->fillset();
+
+Returns C<undef> on failure.
+
+=item ismember
+
+Tests the SigSet object to see if it contains a specific signal.
+
+ if( $sigset->ismember( &POSIX::SIGUSR1 ) ){
+ print "contains SIGUSR1\n";
+ }
+
+=back
+
+=head2 POSIX::Termios
+
+=over 8
+
+=item 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;
+
+=item 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 C<undef> on failure.
+
+=item 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);
+
+=item getcflag
+
+Retrieve the c_cflag field of a termios object.
+
+ $c_cflag = $termios->getcflag;
+
+=item getiflag
+
+Retrieve the c_iflag field of a termios object.
+
+ $c_iflag = $termios->getiflag;
+
+=item getispeed
+
+Retrieve the input baud rate.
+
+ $ispeed = $termios->getispeed;
+
+=item getlflag
+
+Retrieve the c_lflag field of a termios object.
+
+ $c_lflag = $termios->getlflag;
+
+=item getoflag
+
+Retrieve the c_oflag field of a termios object.
+
+ $c_oflag = $termios->getoflag;
+
+=item getospeed
+
+Retrieve the output baud rate.
+
+ $ospeed = $termios->getospeed;
+
+=item setattr
+
+Set terminal control attributes.
+
+Set attributes immediately for stdout.
+
+ $termios->setattr( 1, &POSIX::TCSANOW );
+
+Returns C<undef> on failure.
+
+=item 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 );
+
+=item setcflag
+
+Set the c_cflag field of a termios object.
+
+ $termios->setcflag( $c_cflag | &POSIX::CLOCAL );
+
+=item setiflag
+
+Set the c_iflag field of a termios object.
+
+ $termios->setiflag( $c_iflag | &POSIX::BRKINT );
+
+=item setispeed
+
+Set the input baud rate.
+
+ $termios->setispeed( &POSIX::B9600 );
+
+Returns C<undef> on failure.
+
+=item setlflag
+
+Set the c_lflag field of a termios object.
+
+ $termios->setlflag( $c_lflag | &POSIX::ECHO );
+
+=item setoflag
+
+Set the c_oflag field of a termios object.
+
+ $termios->setoflag( $c_oflag | &POSIX::OPOST );
+
+=item setospeed
+
+Set the output baud rate.
+
+ $termios->setospeed( &POSIX::B9600 );
+
+Returns C<undef> on failure.
+
+=item Baud rate values
+
+B38400 B75 B200 B134 B300 B1800 B150 B0 B19200 B1200 B9600 B600 B4800 B50 B2400 B110
+
+=item Terminal interface values
+
+TCSADRAIN TCSANOW TCOON TCIOFLUSH TCOFLUSH TCION TCIFLUSH TCSAFLUSH TCIOFF TCOOFF
+
+=item c_cc field values
+
+VEOF VEOL VERASE VINTR VKILL VQUIT VSUSP VSTART VSTOP VMIN VTIME NCCS
+
+=item c_cflag field values
+
+CLOCAL CREAD CSIZE CS5 CS6 CS7 CS8 CSTOPB HUPCL PARENB PARODD
+
+=item c_iflag field values
+
+BRKINT ICRNL IGNBRK IGNCR IGNPAR INLCR INPCK ISTRIP IXOFF IXON PARMRK
+
+=item c_lflag field values
+
+ECHO ECHOE ECHOK ECHONL ICANON IEXTEN ISIG NOFLSH TOSTOP
+
+=item c_oflag field values
+
+OPOST
+
+=back
+
+=head1 PATHNAME CONSTANTS
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 POSIX CONSTANTS
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 SYSTEM CONFIGURATION
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 ERRNO
+
+=over 8
+
+=item Constants
+
+E2BIG EACCES EADDRINUSE EADDRNOTAVAIL EAFNOSUPPORT EAGAIN EALREADY EBADF
+EBUSY ECHILD ECONNABORTED ECONNREFUSED ECONNRESET EDEADLK EDESTADDRREQ
+EDOM EDQUOT EEXIST EFAULT EFBIG EHOSTDOWN EHOSTUNREACH EINPROGRESS EINTR
+EINVAL EIO EISCONN EISDIR ELOOP EMFILE EMLINK EMSGSIZE ENAMETOOLONG
+ENETDOWN ENETRESET ENETUNREACH ENFILE ENOBUFS ENODEV ENOENT ENOEXEC
+ENOLCK ENOMEM ENOPROTOOPT ENOSPC ENOSYS ENOTBLK ENOTCONN ENOTDIR
+ENOTEMPTY ENOTSOCK ENOTTY ENXIO EOPNOTSUPP EPERM EPFNOSUPPORT EPIPE
+EPROCLIM EPROTONOSUPPORT EPROTOTYPE ERANGE EREMOTE ERESTART EROFS
+ESHUTDOWN ESOCKTNOSUPPORT ESPIPE ESRCH ESTALE ETIMEDOUT ETOOMANYREFS
+ETXTBSY EUSERS EWOULDBLOCK EXDEV
+
+=back
+
+=head1 FCNTL
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 FLOAT
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 LIMITS
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 LOCALE
+
+=over 8
+
+=item Constants
+
+LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME
+
+=back
+
+=head1 MATH
+
+=over 8
+
+=item Constants
+
+HUGE_VAL
+
+=back
+
+=head1 SIGNAL
+
+=over 8
+
+=item 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
+
+=back
+
+=head1 STAT
+
+=over 8
+
+=item 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
+
+=item Macros
+
+S_ISBLK S_ISCHR S_ISDIR S_ISFIFO S_ISREG
+
+=back
+
+=head1 STDLIB
+
+=over 8
+
+=item Constants
+
+EXIT_FAILURE EXIT_SUCCESS MB_CUR_MAX RAND_MAX
+
+=back
+
+=head1 STDIO
+
+=over 8
+
+=item Constants
+
+BUFSIZ EOF FILENAME_MAX L_ctermid L_cuserid L_tmpname TMP_MAX
+
+=back
+
+=head1 TIME
+
+=over 8
+
+=item Constants
+
+CLK_TCK CLOCKS_PER_SEC
+
+=back
+
+=head1 UNISTD
+
+=over 8
+
+=item Constants
+
+R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STDERR_FILENO W_OK X_OK
+
+=back
+
+=head1 WAIT
+
+=over 8
+
+=item Constants
+
+WNOHANG WUNTRACED
+
+=over 16
+
+=item WNOHANG
+
+Do not suspend the calling process until a child process
+changes state but instead return immediately.
+
+=item WUNTRACED
+
+Catch stopped child processes.
+
+=back
+
+=item Macros
+
+WIFEXITED WEXITSTATUS WIFSIGNALED WTERMSIG WIFSTOPPED WSTOPSIG
+
+=over 16
+
+=item WIFEXITED
+
+WIFEXITED($?) returns true if the child process exited normally
+(C<exit()> or by falling off the end of C<main()>)
+
+=item WEXITSTATUS
+
+WEXITSTATUS($?) returns the normal exit status of the child process
+(only meaningful if WIFEXITED($?) is true)
+
+=item WIFSIGNALED
+
+WIFSIGNALED($?) returns true if the child process terminated because
+of a signal
+
+=item WTERMSIG
+
+WTERMSIG($?) returns the signal the child process terminated for
+(only meaningful if WIFSIGNALED($?) is true)
+
+=item WIFSTOPPED
+
+WIFSTOPPED($?) returns true if the child process is currently stopped
+(can happen only if you specified the WUNTRACED flag to waitpid())
+
+=item WSTOPSIG
+
+WSTOPSIG($?) returns the signal the child process was stopped for
+(only meaningful if WIFSTOPPED($?) is true)
+
+=back
+
+=back
+