Re: [log4perl-devel] fast interface to bash

[Mike S. <m...@pe...>]

On Fri, 18 Nov 2005, Rob Redmon wrote:

> I'm using log4perl in a process safe way using 
> Log::Log4perl::Appender::Synchronized for many perl programs to all write to 
> the same log file.  Our project has a lot of bash code that has been written. 
> I would like all of these bash scripts to send their log messages and their 
> stdout and stderr to the same log file mentioned above.  I need to do this so 
> that log messages do not collide with one another and I cannot afford to pay 
> the startup time that the following perl code takes (about 2 sec on my 
> machine) for each logged message:
>
> use Log::Log4perl qw(get_logger :levels);
> Log::Log4perl->init_and_watch("log.conf", 60);

Hi Rob,

a speedier way to redirect a shell script's messages to a Log4perl appender
is using a pipe to a simple program 'logger.pl' like this:

     #!/usr/bin/perl -w
     # logger.pl
     use strict;
     use Log::Log4perl qw(:easy);
     Log::Log4perl->easy_init({level => $DEBUG, file => ">file.log"});

     while(<>) {
         DEBUG $_;
     }

and call your shell script via

     shellscript.sh 2>&1 | logger.pl

Add different appenders (like Log::Log4perl::Appender::Synchronized) as
needed. Also, if you need different log levels, you could potentially 
included them in the shell script's messages and have logger.pl interpret
them before sending a message to Log4perl.

Alternatively, you could have a standalone C program which takes messages
on the command line and sends them over a socket (connect, send) to a
permanently running perl daemon (using Socket::INET). From the
shell script, you would call it like

     # ... bash code
     clogger "This is my message"

and the permanently running logger daemon would look something like
this:

     use strict;
     use IO::Socket;
     use Log::Log4perl qw(:easy);
     Log::Log4perl->easy_init($DEBUG);

     my $PORT = 9000;
     my $server = IO::Socket::INET->new(
       Proto => 'tcp',
       LocalPort => $PORT,
       Listen    => SOMAXCONN,
       Reuse     => 1);

     die "Can't start server" unless $server;
     print "Server $0 accepting clients\n";

     while(defined( my $client = $server->accept())) {
         $client->autoflush(1);
         print $client "Welcome to $0, send your message\n";
         my $line = <$client>;
         DEBUG "$line" if defined $line;
         close $client;
     }

Hope this helps.

-- Mike

Mike Schilli
m...@pe...