Sys::Syslog, openlog, closelog, setlogmask, syslog - Perl interface to the UNIX syslog(3) calls


    use Sys::Syslog;                          # all except setlogsock, or:
    use Sys::Syslog qw(:DEFAULT setlogsock);  # default set, plus setlogsock

    setlogsock $sock_type;
    openlog $ident, $logopt, $facility;
    syslog $priority, $format, @args;
    $oldmask = setlogmask $mask_priority;


Sys::Syslog is an interface to the UNIX syslog(3) program. Call syslog() with a string priority and a list of printf() args just like syslog(3).

Syslog provides the functions:

openlog $ident, $logopt, $facility

$ident is prepended to every message. $logopt contains zero or more of the words pid, ndelay, cons, nowait. $facility specifies the part of the system

syslog $priority, $format, @args

If $priority permits, logs ($format, @args) printed as by printf(3V), with the addition that %m is replaced with "$!" (the latest error message).

setlogmask $mask_priority

Sets log mask $mask_priority and returns the old mask.

setlogsock $sock_type (added in 5.004_02)

Sets the socket type to be used for the next call to openlog() or syslog() and returns TRUE on success, undef on failure.

A value of 'unix' will connect to the UNIX domain socket returned by _PATH_LOG in A value of 'inet' will connect to an INET socket returned by getservbyname(). Any other value croaks.

The default is for the INET socket to be used.


Closes the log file.

Note that openlog now takes three arguments, just like openlog(3).


    openlog($program, 'cons,pid', 'user');
    syslog('info', 'this is another test');
    syslog('mail|warning', 'this is a better test: %d', time);

    syslog('debug', 'this is the last test');

    openlog("$program $$", 'ndelay', 'user');
    syslog('notice', 'fooprogram: this is really done');

    $! = 55;
    syslog('info', 'problem was %m'); # %m == $! in syslog(3)


Sys::Syslog needs, which can be created with h2ph.




Tom Christiansen <> and Larry Wall <>. UNIX domain sockets added by Sean Robinson <> with support from Tim Bunce <> and the perl5-porters mailing list.


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