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.
+identical or almost 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,
=item C<abs>
-This is identical to Perl's builtin C<abs()> function, returning
-the absolute value of its numerical argument.
+This is identical to Perl's builtin C<abs()> function, returning the absolute
+value of its numerical argument (except that C<POSIX::abs()> must be provided
+an explicit value (rather than relying on an implicit C<$_>):
+
+ $absolute_value = POSIX::abs(42); # good
+
+ $absolute_value = POSIX::abs(); # throws exception
=item C<access>
=item C<alarm>
-This is identical to Perl's builtin C<alarm()> function,
-either for arming or disarming the C<SIGARLM> timer.
+This is identical to Perl's builtin C<alarm()> function, either for arming or
+disarming the C<SIGARLM> timer, except that C<POSIX::alarm()> must be provided
+an explicit value (rather than relying on an implicit C<$_>):
+
+ POSIX::alarm(3) # good
+
+ POSIX::alarm() # throws exception
=item C<asctime>
=item C<chdir>
-This is identical to Perl's builtin C<chdir()> function, allowing
-one to change the working (default) directory, see L<perlfunc/chdir>.
+This is identical to Perl's builtin C<chdir()> function, allowing one to
+change the working (default) directory -- see L<perlfunc/chdir> -- with the
+exception that C<POSIX::chdir()> must be provided an explicit value (rather
+than relying on an implicit C<$_>):
+
+ $rv = POSIX::chdir('path/to/dir'); # good
+
+ $rv = POSIX::chdir(); # throws exception
=item C<chmod>
This is identical to Perl's builtin C<chmod()> function, allowing
-one to change file and directory permissions, see L<perlfunc/chmod>.
+one to change file and directory permissions -- see L<perlfunc/chmod> -- with
+the exception that C<POSIX::chmod()> can only change one file at a time
+(rather than a list of files):
+
+ $c = chmod 0664, $file1, $file2; # good
+
+ $c = POSIX::chmod 0664, $file1; # throws exception
+
+ $c = POSIX::chmod 0664, $file1, $file2; # throws exception
=item C<chown>
should also read L<perllocale>, which provides a comprehensive
discussion of Perl locale handling, including
L<a section devoted to this function|perllocale/The localeconv function>.
+It should not be used in a threaded application unless it's certain that
+the underlying locale is C or POSIX. This is because it otherwise
+changes the locale, which globally affects all threads simultaneously.
Here is how to query the database for the B<de> (Deutsch or German) locale.
=item C<localtime>
This is identical to Perl's builtin C<localtime()> function for
-converting seconds since the epoch to a date see L<perlfunc/localtime>.
+converting seconds since the epoch to a date see L<perlfunc/localtime> except
+that C<POSIX::localtime()> must be provided an explicit value (rather than
+relying on an implicit C<$_>):
+
+ @localtime = POSIX::localtime(time); # good
+
+ @localtime = localtime(); # good
+
+ @localtime = POSIX::localtime(); # throws exception
=item C<log>
See also L</ceil>, L</floor>, L</trunc>.
+Owing to an oversight, this is not currently exported by default, or as part of
+the C<:math_h_c99> export tag; importing it must therefore be done by explicit
+name.
+
=item C<malloc>
Not implemented. C<malloc()> is C-specific. Perl does memory management transparently.
=item C<setlocale>
+WARNING! Do NOT use this function in a L<thread|threads>. The locale
+will change in all other threads at the same time, and should your
+thread get paused by the operating system, and another started, that
+thread will not have the locale it is expecting. On some platforms,
+there can be a race leading to segfaults if two threads call this
+function nearly simultaneously.
+
Modifies and queries the program's underlying locale. Users of this
function should read L<perllocale>, whch provides a comprehensive
discussion of Perl locale handling, knowledge of which is necessary to
the C<strxfrm()> function. Not really needed since
Perl can do this transparently, see L<perllocale>.
+Beware that in a UTF-8 locale, anything you pass to this function must
+be in UTF-8; and when not in a UTF-8 locale, anything passed must not be
+UTF-8 encoded.
+
=item C<strcpy>
Not implemented. C<strcpy()> is C-specific, use C<=> instead, see L<perlop>.
C<strtod> respects any POSIX C<setlocale()> C<LC_TIME> settings,
regardless of whether or not it is called from Perl code that is within
-the scope of S<C<use locale>>.
+the scope of S<C<use locale>>. This means it should not be used in a
+threaded application unless it's certain that the underlying locale is C
+or POSIX. This is because it otherwise changes the locale, which
+globally affects all threads simultaneously.
To parse a string C<$str> as a floating point number use
Not really needed since Perl can do this transparently, see
L<perllocale>.
+Beware that in a UTF-8 locale, anything you pass to this function must
+be in UTF-8; and when not in a UTF-8 locale, anything passed must not be
+UTF-8 encoded.
+
=item C<sysconf>
Retrieves values of system configurable variables.
=item C<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 C<tmpnam()> function, this interface
-should not be used; instead see L<File::Temp>.
+is no longer available; instead use L<File::Temp>.
=item C<tolower>
=back
+=head1 RESOURCE CONSTANTS
+
+Imported with the C<:sys_resource_h> tag.
+
+=over 8
+
+=item Constants
+
+C<PRIO_PROCESS> C<PRIO_PGRP> C<PRIO_USER>
+
+=back
+
=head1 SYSTEM CONFIGURATION
=over 8
=item Constants
-C<BUFSIZ> C<EOF> C<FILENAME_MAX> C<L_ctermid> C<L_cuserid> C<L_tmpname> C<TMP_MAX>
+C<BUFSIZ> C<EOF> C<FILENAME_MAX> C<L_ctermid> C<L_cuserid> C<TMP_MAX>
=back
=back
+=head1 WINSOCK
+
+(Windows only.)
+
+=over 8
+
+=item Constants
+
+C<WSAEINTR> C<WSAEBADF> C<WSAEACCES> C<WSAEFAULT> C<WSAEINVAL> C<WSAEMFILE> C<WSAEWOULDBLOCK>
+C<WSAEINPROGRESS> C<WSAEALREADY> C<WSAENOTSOCK> C<WSAEDESTADDRREQ> C<WSAEMSGSIZE>
+C<WSAEPROTOTYPE> C<WSAENOPROTOOPT> C<WSAEPROTONOSUPPORT> C<WSAESOCKTNOSUPPORT>
+C<WSAEOPNOTSUPP> C<WSAEPFNOSUPPORT> C<WSAEAFNOSUPPORT> C<WSAEADDRINUSE>
+C<WSAEADDRNOTAVAIL> C<WSAENETDOWN> C<WSAENETUNREACH> C<WSAENETRESET> C<WSAECONNABORTED>
+C<WSAECONNRESET> C<WSAENOBUFS> C<WSAEISCONN> C<WSAENOTCONN> C<WSAESHUTDOWN>
+C<WSAETOOMANYREFS> C<WSAETIMEDOUT> C<WSAECONNREFUSED> C<WSAELOOP> C<WSAENAMETOOLONG>
+C<WSAEHOSTDOWN> C<WSAEHOSTUNREACH> C<WSAENOTEMPTY> C<WSAEPROCLIM> C<WSAEUSERS>
+C<WSAEDQUOT> C<WSAESTALE> C<WSAEREMOTE> C<WSAEDISCON> C<WSAENOMORE> C<WSAECANCELLED>
+C<WSAEINVALIDPROCTABLE> C<WSAEINVALIDPROVIDER> C<WSAEPROVIDERFAILEDINIT>
+C<WSAEREFUSED>
+
+=back
+
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