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. Things which are C<#defines> in C, like EINTR or O_NDELAY, are
-automatically exported into your namespace. All functions are only exported
-if you ask for them explicitly. Most likely people will prefer to use the
-fully-qualified function names.
+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
and dynamic loading of code that's in Perl, C, or both. It's a great
source of wisdom.
-=head1 CAVEATS
+=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
=item _exit
-This is identical to the C function C<_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()>.
+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.
+This is identical to Perl's builtin C<abs()> function, returning
+the absolute value of its numerical argument.
=item access
print "have read permission\n";
}
-Returns C<undef> on failure.
+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()>.
+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.
+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()>.
+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<$year> is
+1900-based: 2001 equals C<101>. The C<$wday>, C<$yday>, and C<$isdst>
+default to zero (and the first two are usually ignored anyway).
=item asin
-This is identical to the C function C<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.
+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()>.
+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.
+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 END {} instead.
+atexit() is C-specific: use C<END {}> instead, see L<perlsub>.
=item atof
-atof() is C-specific.
+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.
+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.
+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.
+bsearch() not supplied. For doing binary search on wordlists,
+see L<Search::Dict>.
=item calloc
-calloc() is C-specific.
+calloc() is C-specific. Perl does memory management transparently.
=item ceil
-This is identical to the C function C<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.
+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.
+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.
+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 method C<FileHandle::clearerr()> instead.
+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()>.
+This is identical to the C function C<clock()>, returning the
+amount of spent processor time in microseconds.
=item close
Returns C<undef> on failure.
+See also L<perlfunc/close>.
+
=item closedir
-This is identical to Perl's builtin C<closedir()> function.
+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.
+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()>.
+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
$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.
=item ctime
-This is identical to the C function C<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 character login name of the user.
+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()>.
+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.
+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()>.
+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>.
=item dup2
-This is similar to the C function C<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>.
$errno = POSIX::errno();
+This identical to the numerical values of the C<$!>, see L<perlvar/$ERRNO>.
+
=item execl
-execl() is C-specific.
+execl() is C-specific, see L<perlfunc/exec>.
=item execle
-execle() is C-specific.
+execle() is C-specific, see L<perlfunc/exec>.
=item execlp
-execlp() is C-specific.
+execlp() is C-specific, see L<perlfunc/exec>.
=item execv
-execv() is C-specific.
+execv() is C-specific, see L<perlfunc/exec>.
=item execve
-execve() is C-specific.
+execve() is C-specific, see L<perlfunc/exec>.
=item execvp
-execvp() is C-specific.
+execvp() is C-specific, see L<perlfunc/exec>.
=item exit
-This is identical to Perl's builtin C<exit()> function.
+This is identical to Perl's builtin C<exit()> function for exiting the
+program, see L<perlfunc/exit>.
=item exp
-This is identical to Perl's builtin C<exp()> function.
+This is identical to Perl's builtin C<exp()> function for
+returning the exponent (I<e>-based) of the numerical argument,
+see L<perlfunc/exp>.
=item fabs
-This is identical to Perl's builtin C<abs()> function.
+This is identical to Perl's builtin C<abs()> function for returning
+the absolute value of the numerical argument, see L<perlfunc/abs>.
=item fclose
-Use method C<FileHandle::close()> instead.
+Use method C<IO::Handle::close()> instead, or see L<perlfunc/close>.
=item fcntl
-This is identical to Perl's builtin C<fcntl()> function.
+This is identical to Perl's builtin C<fcntl()> function,
+see L<perlfunc/fcntl>.
=item fdopen
-Use method C<FileHandle::new_from_fd()> instead.
+Use method C<IO::Handle::new_from_fd()> instead, or see L<perlfunc/open>.
=item feof
-Use method C<FileHandle::eof()> instead.
+Use method C<IO::Handle::eof()> instead, or see L<perlfunc/eof>.
=item ferror
-Use method C<FileHandle::error()> instead.
+Use method C<IO::Handle::error()> instead.
=item fflush
-Use method C<FileHandle::flush()> instead.
+Use method C<IO::Handle::flush()> instead.
+See also L<perlvar/$OUTPUT_AUTOFLUSH>.
=item fgetc
-Use method C<FileHandle::getc()> instead.
+Use method C<IO::Handle::getc()> instead, or see L<perlfunc/read>.
=item fgetpos
-Use method C<FileHandle::getpos()> instead.
+Use method C<IO::Seekable::getpos()> instead, or see L<L/seek>.
=item fgets
-Use method C<FileHandle::gets()> instead.
+Use method C<IO::Handle::gets()> instead. Similar to E<lt>E<gt>, also known
+as L<perlfunc/readline>.
=item fileno
-Use method C<FileHandle::fileno()> instead.
+Use method C<IO::Handle::fileno()> instead, or see L<perlfunc/fileno>.
=item floor
-This is identical to the C function C<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<FileHandle::open()> instead.
+Use method C<IO::File::open()> instead, or see L<perlfunc/open>.
=item fork
-This is identical to Perl's builtin C<fork()> function.
+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
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</tmp/foo>.
+pathname on the filesystem which holds C</var/foo>.
- $fd = POSIX::open( "/tmp/foo", &POSIX::O_RDONLY );
+ $fd = POSIX::open( "/var/foo", &POSIX::O_RDONLY );
$path_max = POSIX::fpathconf( $fd, &POSIX::_PC_PATH_MAX );
Returns C<undef> on failure.
=item fprintf
-fprintf() is C-specific--use printf instead.
+fprintf() is C-specific, see L<perlfunc/printf> instead.
=item fputc
-fputc() is C-specific--use print instead.
+fputc() is C-specific, see L<perlfunc/print> instead.
=item fputs
-fputs() is C-specific--use print instead.
+fputs() is C-specific, see L<perlfunc/print> instead.
=item fread
-fread() is C-specific--use read instead.
+fread() is C-specific, see L<perlfunc/read> instead.
=item free
-free() is C-specific.
+free() is C-specific. Perl does memory management transparently.
=item freopen
-freopen() is C-specific--use open instead.
+freopen() is C-specific, see L<perlfunc/open> instead.
=item frexp
Return the mantissa and exponent of a floating-point number.
- ($mantissa, $exponent) = POSIX::frexp( 3.14 );
+ ($mantissa, $exponent) = POSIX::frexp( 1.234e56 );
=item fscanf
-fscanf() is C-specific--use <> and regular expressions instead.
+fscanf() is C-specific, use E<lt>E<gt> and regular expressions instead.
=item fseek
-Use method C<FileHandle::seek()> instead.
+Use method C<IO::Seekable::seek()> instead, or see L<perlfunc/seek>.
=item fsetpos
-Use method C<FileHandle::setpos()> instead.
+Use method C<IO::Seekable::setpos()> instead, or seek L<perlfunc/seek>.
=item fstat
$fd = POSIX::open( "foo", &POSIX::O_RDONLY );
@stats = POSIX::fstat( $fd );
+=item fsync
+
+Use method C<IO::Handle::sync()> instead.
+
=item ftell
-Use method C<FileHandle::tell()> instead.
+Use method C<IO::Seekable::tell()> instead, or see L<perlfunc/tell>.
=item fwrite
-fwrite() is C-specific--use print instead.
+fwrite() is C-specific, see L<perlfunc/print> instead.
=item getc
-This is identical to Perl's builtin C<getc()> function.
+This is identical to Perl's builtin C<getc()> function,
+see L<perlfunc/getc>.
=item getchar
-Returns one character from STDIN.
+Returns one character from STDIN. Identical to Perl's C<getc()>,
+see L<perlfunc/getc>.
=item getcwd
Returns the name of the current working directory.
+See also L<Cwd>.
=item getegid
-Returns the effective group id.
+Returns the effective group identifier. Similar to Perl' s builtin
+variable C<$(>, see L<perlvar/$EGID>.
=item getenv
-Returns the value of the specified enironment variable.
+Returns the value of the specified environment variable.
+The same information is available through the C<%ENV> array.
=item geteuid
-Returns the effective user id.
+Returns the effective user identifier. Identical to Perl's builtin C<$E<gt>>
+variable, see L<perlvar/$EUID>.
=item getgid
-Returns the user's real group id.
+Returns the user's real group identifier. Similar to Perl's builtin
+variable C<$)>, see L<perlvar/$GID>.
=item getgrgid
-This is identical to Perl's builtin C<getgrgid()> function.
+This is identical to Perl's builtin C<getgrgid()> function for
+returning group entries by group identifiers, see
+L<perlfunc/getgrgid>.
=item getgrnam
-This is identical to Perl's builtin C<getgrnam()> function.
+This is identical to Perl's builtin C<getgrnam()> function for
+returning group entries by group names, see L<perlfunc/getgrnam>.
=item getgroups
-Returns the ids of the user's supplementary groups.
+Returns the ids of the user's supplementary groups. Similar to Perl's
+builtin variable C<$)>, see L<perlvar/$GID>.
=item getlogin
-This is identical to Perl's builtin C<getlogin()> function.
+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.
+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's id.
+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.
+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.
+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.
+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 STDIN.
+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 id.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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.
+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
-labs() is C-specific, use abs instead.
+(For returning absolute values of long integers.)
+labs() is C-specific, see L<perlfunc/abs> instead.
=item ldexp
-This is identical to the C function C<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
-ldiv() is C-specific, use / and int instead.
+(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.
+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.
-The database for the B<de> (Deutsch or German) locale.
+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";
=item localtime
-This is identical to Perl's builtin C<localtime()> function.
+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.
+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()>.
+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 die instead.
+longjmp() is C-specific: use L<perlfunc/die> instead.
=item lseek
-Move the read/write file pointer. This uses file descriptors such as
+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 );
=item malloc
-malloc() is C-specific.
+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, use index() instead.
+memchr() is C-specific, see L<perlfunc/index> instead.
=item memcmp
-memcmp() is C-specific, use eq instead.
+memcmp() is C-specific, use C<eq> instead, see L<perlop>.
=item memcpy
-memcpy() is C-specific, use = instead.
+memcpy() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
=item memmove
-memmove() is C-specific, use = instead.
+memmove() is C-specific, use C<=>, see L<perlop>, or see L<perlfunc/substr>.
=item memset
-memset() is C-specific, use x instead.
+memset() is C-specific, use C<x> instead, see L<perlop>.
=item mkdir
-This is identical to Perl's builtin C<mkdir()> function.
+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()>.
+This is similar to the C function C<mkfifo()> for creating
+FIFO special files.
-Returns C<undef> on failure.
+ 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
=item nice
-This is similar to the C function C<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.
+offsetof() is C-specific, you probably want to see L<perlfunc/pack> instead.
=item open
Returns C<undef> on failure.
+See also L<perlfunc/sysopen>.
+
=item opendir
Open a directory for reading.
- $dir = POSIX::opendir( "/tmp" );
+ $dir = POSIX::opendir( "/var" );
@files = POSIX::readdir( $dir );
POSIX::closedir( $dir );
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</tmp>.
+pathname on the filesystem which holds C</var>.
- $path_max = POSIX::pathconf( "/tmp", &POSIX::_PC_PATH_MAX );
+ $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()>.
+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()>.
+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>.
- ($fd0, $fd1) = POSIX::pipe();
- POSIX::write( $fd0, "hello", 5 );
- POSIX::read( $fd1, $buf, 5 );
+ my ($read, $write) = POSIX::pipe();
+ POSIX::write( $write, "hello", 5 );
+ POSIX::read( $read, $buf, 5 );
+
+See also L<perlfunc/pipe>.
=item pow
-Computes $x raised to the power $exponent.
+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
-Prints the specified arguments to STDOUT.
+Formats and prints the specified arguments to STDOUT.
+See also L<perlfunc/printf>.
=item putc
-putc() is C-specific--use print instead.
+putc() is C-specific, see L<perlfunc/print> instead.
=item putchar
-putchar() is C-specific--use print instead.
+putchar() is C-specific, see L<perlfunc/print> instead.
=item puts
-puts() is C-specific--use print instead.
+puts() is C-specific, see L<perlfunc/print> instead.
=item qsort
-qsort() is C-specific, use sort instead.
+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/$PID>.
=item rand
-rand() is non-portable, use Perl's rand instead.
+C<rand()> is non-portable, see L<perlfunc/rand> instead.
=item read
Returns C<undef> on failure.
+See also L<perlfunc/sysread>.
+
=item readdir
-This is identical to Perl's builtin C<readdir()> function.
+This is identical to Perl's builtin C<readdir()> function
+for reading directory entries, see L<perlfunc/readdir>.
=item realloc
-realloc() is C-specific.
+realloc() is C-specific. Perl does memory management transparently.
=item remove
-This is identical to Perl's builtin C<unlink()> function.
+This is identical to Perl's builtin C<unlink()> function
+for removing files, see L<perlfunc/unlink>.
=item rename
-This is identical to Perl's builtin C<rename()> function.
+This is identical to Perl's builtin C<rename()> function
+for renaming files, see L<perlfunc/rename>.
=item rewind
=item rewinddir
-This is identical to Perl's builtin C<rewinddir()> function.
+This is identical to Perl's builtin C<rewinddir()> function for
+rewinding directory entry streams, see L<perlfunc/rewinddir>.
=item rmdir
-This is identical to Perl's builtin C<rmdir()> function.
+This is identical to Perl's builtin C<rmdir()> function
+for removing (empty) directories, see L<perlfunc/rmdir>.
=item scanf
-scanf() is C-specific--use <> and regular expressions instead.
+scanf() is C-specific, use E<lt>E<gt> and regular expressions instead,
+see L<perlre>.
=item setgid
-Sets the real group id for this process.
+Sets the real group identifier and the effective group identifier for
+this process. Similar to assigning a value to the Perl's builtin
+C<$)> variable, see L<perlvar/$GID>, 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
-setjmp() is C-specific: use eval {} instead.
+C<setjmp()> is C-specific: use C<eval {}> instead,
+see L<perlfunc/eval>.
=item setlocale
-Modifies and queries program's locale.
+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 = POSIX::setlocale( &POSIX::LC_ALL, "C" );
+ $loc = setlocale( LC_ALL, "C" );
-The following will query (the missing second argument) the current
-LC_CTYPE category.
+The following will query the current LC_CTYPE category. (No second
+argument means 'query'.)
- $loc = POSIX::setlocale( &POSIX::LC_CTYPE);
+ $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 L<setlocale(3)> documentation for the locale
-environment variables' meaning or consult L<perli18n>.
+Please see your systems C<setlocale(3)> documentation for the locale
+environment variables' meaning or consult L<perllocale>.
- $loc = POSIX::setlocale( &POSIX::LC_CTYPE, "");
+ $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<perli18n> for how to find
+your operating system. Please consult L<perllocale> for how to find
out which locales are available in your system.
- $loc = POSIX::setlocale( &POSIX::LC_ALL, "es_AR.ISO8859-1" );
+ $loc = setlocale( LC_ALL, "es_AR.ISO8859-1" );
=item setpgid
-This is similar to the C function C<setpgid()>.
+This is similar to the C function C<setpgid()> for
+setting the process group identifier of the current process.
Returns C<undef> on failure.
=item setsid
-This is identical to the C function C<setsid()>.
+This is identical to the C function C<setsid()> for
+setting the session identifier of the current process.
=item setuid
-Sets the real user id for this process.
+Sets the real user identifier and the effective user identifier for
+this process. Similar to assigning a value to the Perl's builtin
+C<$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. Consult your system's C<sigaction>
-manpage for details.
+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(sig, action, oldaction = 0)
+ sigaction(signal, action, oldaction = 0)
-Returns C<undef> on failure.
+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 die instead.
+siglongjmp() is C-specific: use L<perlfunc/die> instead.
=item sigpending
=item sigsetjmp
-sigsetjmp() is C-specific: use eval {} instead.
+C<sigsetjmp()> is C-specific: use C<eval {}> instead,
+see L<perlfunc/eval>.
=item sigsuspend
=item sin
-This is identical to Perl's builtin C<sin()> function.
+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()>.
+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 identical to Perl's builtin C<sleep()> function.
+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 identical to Perl's builtin C<sprintf()> function.
+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
-srand().
+Give a seed the pseudorandom number generator, see L<perlfunc/srand>.
=item sscanf
-sscanf() is C-specific--use regular expressions instead.
+sscanf() is C-specific, use regular expressions instead,
+see L<perlre>.
=item stat
-This is identical to Perl's builtin C<stat()> function.
+This is identical to Perl's builtin C<stat()> function
+for returning information about files and directories.
=item strcat
-strcat() is C-specific, use .= instead.
+strcat() is C-specific, use C<.=> instead, see L<perlop>.
=item strchr
-strchr() is C-specific, use index() instead.
+strchr() is C-specific, see L<perlfunc/index> instead.
=item strcmp
-strcmp() is C-specific, use eq instead.
+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()>.
+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 = instead.
+strcpy() is C-specific, use C<=> instead, see L<perlop>.
=item strcspn
-strcspn() is C-specific, use regular expressions instead.
+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
Synopsis:
- strftime(fmt, sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)
+ 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 (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 );
=item strlen
-strlen() is C-specific, use length instead.
+strlen() is C-specific, use C<length()> instead, see L<perlfunc/length>.
=item strncat
-strncat() is C-specific, use .= instead.
+strncat() is C-specific, use C<.=> instead, see L<perlop>.
=item strncmp
-strncmp() is C-specific, use eq instead.
+strncmp() is C-specific, use C<eq> instead, see L<perlop>.
=item strncpy
-strncpy() is C-specific, use = instead.
-
-=item stroul
-
-stroul() is C-specific.
+strncpy() is C-specific, use C<=> instead, see L<perlop>.
=item strpbrk
-strpbrk() is C-specific.
+strpbrk() is C-specific, use regular expressions instead,
+see L<perlre>.
=item strrchr
-strrchr() is C-specific, use rindex() instead.
+strrchr() is C-specific, see L<perlfunc/rindex> instead.
=item strspn
-strspn() is C-specific.
+strspn() is C-specific, use regular expressions instead,
+see L<perlre>.
=item strstr
-This is identical to Perl's builtin C<index()> function.
+This is identical to Perl's builtin C<index()> function,
+see L<perlfunc/index>.
=item strtod
The second returned item and $! can be used to check for valid input:
- if (($str eq '') || ($n_unparsed != 0) || !$!) {
- die "Non-numeric input $str" . $! ? ": $!\n" : "\n";
+ if (($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.
+strtok() is C-specific, use regular expressions instead, see
+L<perlre>, or L<perlfunc/split>.
=item strtol
=item strtoul
-String to unsigned (long) integer translation. strtoul is identical
-to strtol except that strtoul only parses unsigned integers. See
-I<strtol> for details.
+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 suply strtoul parse "-1" as a valid value.
+Note: Some vendors supply strtod() and strtol() but not strtoul().
+Other vendors that do supply strtoul() parse "-1" as a valid value.
=item strxfrm
$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.
=item system
-This is identical to Perl's builtin C<system()> function.
+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()>.
+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()>.
+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()>.
+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()>.
+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()>.
+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()>.
+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()>.
+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()>.
+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.
+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
=item tmpfile
-Use method C<FileHandle::new_tmpfile()> instead.
+Use method C<IO::File::new_tmpfile()> instead, or see L<File::Temp>.
=item tmpnam
$tmpfile = POSIX::tmpnam();
+For security reasons, which are probably detailed in your system's
+documentation for the C library tmpnam() function, this interface
+should not be used; instead see L<File::Temp>.
+
=item tolower
-This is identical to Perl's builtin C<lc()> function.
+This is identical to the C function, except that it can apply to a single
+character or to a whole string. Consider using the C<lc()> function,
+see L<perlfunc/lc>, or the equivalent C<\L> operator inside doublequotish
+strings.
=item toupper
-This is identical to Perl's builtin C<uc()> function.
+This is identical to the C function, except that it can apply to a single
+character or to a whole string. Consider using the C<uc()> function,
+see L<perlfunc/uc>, or the equivalent C<\U> operator inside doublequotish
+strings.
=item ttyname
-This is identical to the C function C<ttyname()>.
+This is identical to the C function C<ttyname()> for returning the
+name of the current terminal.
=item tzname
=item tzset
-This is identical to the C function C<tzset()>.
+This is identical to the C function C<tzset()> for setting
+the current timezone based on the environment variable C<TZ>,
+to be used by C<ctime()>, C<localtime()>, C<mktime()>, and C<strftime()>
+functions.
=item umask
-This is identical to Perl's builtin C<umask()> function.
+This is identical to Perl's builtin C<umask()> function
+for setting (and querying) the file creation permission mask,
+see L<perlfunc/umask>.
=item uname
Get name of current operating system.
- ($sysname, $nodename, $release, $version, $machine ) = POSIX::uname();
+ ($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<FileHandle::ungetc()> instead.
+Use method C<IO::Handle::ungetc()> instead.
=item unlink
-This is identical to Perl's builtin C<unlink()> function.
+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.
+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.
+vfprintf() is C-specific, see L<perlfunc/printf> instead.
=item vprintf
-vprintf() is C-specific.
+vprintf() is C-specific, see L<perlfunc/printf> instead.
=item vsprintf
-vsprintf() is C-specific.
+vsprintf() is C-specific, see L<perlfunc/sprintf> instead.
=item wait
-This is identical to Perl's builtin C<wait()> function.
+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.
+builtin C<waitpid()> function, see L<perlfunc/waitpid>.
- $pid = POSIX::waitpid( -1, &POSIX::WNOHANG );
+ $pid = POSIX::waitpid( -1, POSIX::WNOHANG );
print "status = ", ($? / 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
Returns C<undef> on failure.
+See also L<perlfunc/syswrite>.
+
=back
=head1 CLASSES
=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 fully-qualified name of a sub
-which is a signal-handler. The second parameter is a C<POSIX::SigSet>
-object. The third parameter contains the C<sa_flags>.
+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;
- $sigaction = POSIX::SigAction->new( 'main::handler', $sigset, &POSIX::SA_NOCLDSTOP );
+ $sigset = POSIX::SigSet->new(SIGINT, SIGQUIT);
+ $sigaction = POSIX::SigAction->new( \&handler, $sigset, &POSIX::SA_NOCLDSTOP );
-This C<POSIX::SigAction> object should be used with the C<POSIX::sigaction()>
+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 $POSIX::RtSig::SIGACTION_FLAGS, or you can
+derive from POSIX::SigRt and define your own C<new()> (the tied hash
+STORE method of the %SIGRT calls C<new($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 Termios object. This object will be destroyed automatically
-when it is no longer needed.
+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;
Obtain the attributes for stdin.
+ $termios->getattr( 0 ) # Recommended for clarity.
$termios->getattr()
Obtain the attributes for stdout.
Set the c_cflag field of a termios object.
- $termios->setcflag( &POSIX::CLOCAL );
+ $termios->setcflag( $c_cflag | &POSIX::CLOCAL );
=item setiflag
Set the c_iflag field of a termios object.
- $termios->setiflag( &POSIX::BRKINT );
+ $termios->setiflag( $c_iflag | &POSIX::BRKINT );
=item setispeed
Set the c_lflag field of a termios object.
- $termios->setlflag( &POSIX::ECHO );
+ $termios->setlflag( $c_lflag | &POSIX::ECHO );
=item setoflag
Set the c_oflag field of a termios object.
- $termios->setoflag( &POSIX::OPOST );
+ $termios->setoflag( $c_oflag | &POSIX::OPOST );
=item setospeed
=item Constants
-_SC_ARG_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_JOB_CONTROL _SC_NGROUPS_MAX _SC_OPEN_MAX _SC_SAVED_IDS _SC_STREAM_MAX _SC_TZNAME_MAX _SC_VERSION
+_SC_ARG_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_JOB_CONTROL _SC_NGROUPS_MAX _SC_OPEN_MAX _SC_PAGESIZE _SC_SAVED_IDS _SC_STREAM_MAX _SC_TZNAME_MAX _SC_VERSION
=back
=item Constants
-E2BIG EACCES EAGAIN EBADF EBUSY ECHILD EDEADLK EDOM EEXIST EFAULT EFBIG EINTR EINVAL EIO EISDIR EMFILE EMLINK ENAMETOOLONG ENFILE ENODEV ENOENT ENOEXEC ENOLCK ENOMEM ENOSPC ENOSYS ENOTDIR ENOTEMPTY ENOTTY ENXIO EPERM EPIPE ERANGE EROFS ESPIPE ESRCH EXDEV
+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
=item Constants
-SA_NOCLDSTOP 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
+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
=item Constants
-R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STRERR_FILENO W_OK X_OK
+R_OK SEEK_CUR SEEK_END SEEK_SET STDIN_FILENO STDOUT_FILENO STDERR_FILENO W_OK X_OK
=back
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
-=back
+=over 16
-=head1 CREATION
+=item WIFEXITED
-This document generated by ./mkposixman.PL version 19960129.
+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