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Aaron Brown > perfSONAR_PS-Services-MA-perfSONARBUOY-0.09 > perfSONAR_PS::OWP::Syslog



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Module Version: 0.09   Source  


perfSONAR_PS::OWP::Syslog - Tie a filehandle to Syslog. If you Tie STDERR, then all STDERR errors are automatically caught, or you can debug by Carp'ing to STDERR, etc. (Good for CGI error logging.)




















  use perfSONAR_PS::OWP::Syslog;

  ##  Pass up to five args:
  ##    facility        => 'local0',
  ##    priority        => 'err',
  ##    identity        => 'my_program'
  ##    log_opts        => 'pid,cons'           # defaults to 'pid'
  ##    setlogsock      => 'inet'|'unix'        # defaults to inet
  tie *MYLOG, 'Tie::Syslog', facility => 'local0', setlogsock => 'unix';
  print MYLOG "I made an error."; ## this will be syslogged
  printf MYLOG "Error %d", 42;    ## syslog as "Error 42"

  untie *MYLOG;


This module allows you to tie a filehandle (output only) to syslog. This becomes useful in general when you want to capture any activity that happens on STDERR and see that it is syslogged for later perusal. You can also create an arbitrary filehandle, say LOG, and send stuff to syslog by printing to this filehandle. This module depends on the Sys::Syslog module to actually get info to syslog.

Tie your filehandle to syslog using a glob to the filehandle. When it is tied to the 'Tie::Syslog' class, you may optionally pass four arguments that determine the behavior of the output bound to syslog.

The arguments are specified in any order using hash-array notation.

The 'facility' and 'priority' are used to direct your filehandle traffic to the proper channels in syslog. I suggest reviewing a manpage for syslog on your local system to identify what the facilities and priorities actually are. (The defaults are set to 'local0' and 'err' respectively.

The 'identifier' string is the string that shows up in evey line of output that syslog writes. You may use this identifier to help sort out syslog lines produced by different applications (with different id's.) If you do not specify a value for this argument, it will default to the name of the running program. (This is derived from FindBin::Script.)

The 'log_opts' is a string of comma separated log options specific to syslog. Current documentation supports 'pid,cons,ndelay,nowait'. Check your local listings, as you may pass values that are only part of your local system. I suggest checking your man pages for syslog, and perhaps looking inside your site_perl/$archname/sys/ for other such values. If you do not pass this argument, it defaults to the string 'pid', which makes syslog put a [12345] pid value on each line of output.

The 'setlogsock' argument is either the string 'inet' or 'unix'. This is passed to the Sys::Syslog::setlogsock() call to specify the socket type to be used when opening the connection to syslog. If this argument is not specified, then the default used is 'inet'. Many perl installations still have original Sys::Syslog which does not have the setlogsock() routine. There is also no $VERSION constant to test in Sys::Syslog, so we'll test the symbol table to see if the routine exists. If the routine does not exist, then the fourth argument is silently ignored. I did not want to require people to have "the latest" version of perl just to use this module.

Note: You can optionally pass a reference to a Filehandle as the *very* first arg (before the 'Tie::Syslog' even...) The *only* time you'd do this is if you are experiencing trouble using your tied filehandle with other code that expects to do calls like fileno() and binmode() to operate on this tied filehandle. The TIEHANDLE api gives us no way (that I have found) to get access to the actual tied variable, or filehandle in this case. So, I have resorted to just passing it in as a arg right up front and just storing it in the object. **THERE ARE PROBLEMS WITH THIS!!!** Be aware, those of you this may affect...

An aside on catching die/warn messages:


The blessed object that is returned from tie also has one additional member function. In the case that you want to capture information going to the warn() and die() functions. You may call HandleDieWarn() to setup the proper handler function to deal with the special signals __DIE__ and __WARN__. (The args to HandleDieWarn are a list of fh's to optionally send the message to as well as syslog. If you send the "tied" fh, you will see the message in syslog twice, so don't do that.)

  my $x = tie *MYLOG, 'perfSONAR_PS::OWP::Syslog', priority => 'debug';
  $x->HandleDieWarn(*STDERR);           ## set __DIE__,__WARN__ handler
                                        ## can undef $x anytime after this...
                                        ## arg is filehandle from "tie"

  print STDERR "I made an error.";      ## this will be syslogged
  printf STDERR "Error %d", 42;         ## syslog as "Error 42"
  warn "Another error was made.";       ## this will also be syslogged
  eval {
      die "exception thrown";           ## this is *NOT* syslogged
  die "Killing me softly?!";            ## syslogged, then script ends

  undef $x;                             ## be sure to do this, or warns!
  untie *STDERR;


Sys::Syslog, FindBin

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The perfSONAR-PS subversion repository is located at:

Questions and comments can be directed to the author, or the mailing list. Bugs, feature requests, and improvements can be directed here:


$Id: 1877 2008-03-27 16:33:01Z aaron $


Jeff Boote, Jason Zurawski,


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Copyright (c) 2002 UCAID (Jeff Boote). All rights reserved. This program has been modified from the original version by Broc Seib. It is of course still free software; and can be redistributed and/or modified under the same terms as Perl itself. (GNU License)

Copyright (c) 1999-2002 Broc Seib. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

Copyright (c) 2002-2008, Internet2

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