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
$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).
+1900-based: 2001 equals C<101>. C<$wday> and C<$yday> default to zero
+(and are usually ignored anyway), and C<$isdst> defaults to -1.
=item asin
=item getenv
-Returns the value of the specified enironment variable.
+Returns the value of the specified environment variable.
The same information is available through the C<%ENV> array.
=item geteuid
=item getpgrp
This is identical to Perl's builtin C<getpgrp()> function for
-returning the prcess group identifier of the current process, see
+returning the process group identifier of the current process, see
L<perlfunc/getpgrp>.
=item getpid
or
- sub log10 { log($_[0]) / 2.30258509299405 }
+ sub log10 { log($_[0]) / 2.30258509299405 }
or
This is identical to the C function C<mblen()>.
Perl does not have any support for the wide and multibyte
-characters of the C standards, so this might be a rather
+characters of the C standards, so this might be a rather
useless function.
=item mbstowcs
This is identical to the C function C<mbstowcs()>.
Perl does not have any support for the wide and multibyte
-characters of the C standards, so this might be a rather
+characters of the C standards, so this might be a rather
useless function.
=item mbtowc
This is identical to the C function C<mbtowc()>.
Perl does not have any support for the wide and multibyte
-characters of the C standards, so this might be a rather
+characters of the C standards, so this might be a rather
useless function.
=item memchr
if (mkfifo($path, $mode)) { ....
Returns C<undef> on failure. The C<$mode> is similar to the
-mode of C<mkdir()>, see L<perlfunc/mkdir>.
+mode of C<mkdir()>, see L<perlfunc/mkdir>, though for C<mkfifo>
+you B<must> specify the C<$mode>.
=item mktime
Synopsis:
- mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = 0)
+ mktime(sec, min, hour, mday, mon, year, wday = 0, yday = 0, isdst = -1)
The month (C<mon>), weekday (C<wday>), and yearday (C<yday>) begin at zero.
I.e. January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1. The
Sets the real group identifier and the effective group identifier for
this process. Similar to assigning a value to the Perl's builtin
-C<$)> variable, see L<perlvar/$GID>, except that the latter
+C<$)> 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 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:
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.
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
+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 stat
This is identical to Perl's builtin C<stat()> function
-for retutning information about files and directories.
+for returning information about files and directories.
=item strcat
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.
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
+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
+characters of the C standards, so this might be a rather
useless function.
=item write
$fd = POSIX::open( "foo", &POSIX::O_WRONLY );
$buf = "hello";
- $bytes = POSIX::write( $b, $buf, 5 );
+ $bytes = POSIX::write( $fd, $buf, 5 );
Returns C<undef> on failure.
=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, it defaults to the empty set. The third parameter contains the
+C<struct sigaction>. This object will be destroyed automatically when
+it is no longer needed. The first parameter is the handler, a sub
+reference. The second parameter is a 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( \&main::handler, $sigset, &POSIX::SA_NOCLDSTOP );
+ $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
+=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
Obtain the attributes for stdin.
+ $termios->getattr( 0 ) # Recommended for clarity.
$termios->getattr()
Obtain the attributes for stdout.
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