Formatting STDERR

DaWolf has asked for the wisdom of the Perl Monks concerning the following question:

Greetings.

I have an application the outuputs STDERR to a file, in this form:

# The aaplication begins with:

my $err_file = "error.log";
open(ERRLOG, "+>>logs/system/$err_file");
flock(ERRLOG,2);

*STDERR = *ERRLOG;


# and ends with:

flock(ERRLOG,8);
close(ERRLOG);
[download]

I'd like to prepend every error msg with date and time. Is it possible? I know how to do it in an ordinary string, but can I tell Perl that every STDERR should be formatted in this way?

Thanks in advance,

my ($author_nickname, $author_email) = ("DaWolf","erabbott\@terra.com.br") if ($author_name eq "Er Galvão Abbott");

Comment on Formatting STDERR Download Code

Replies are listed 'Best First'.
Re: Formatting STDERR by Corion (Patriarch) on Feb 12, 2004 at 10:00 UTC
merlyn has a nifty routine for that, which I shamelessly stole for Simple HTTP in under 100 lines : `$SIG{__WARN__} = sub { warn __stamp(shift) }; $SIG{__DIE__} = sub { die __stamp(shift) }; # This sub Copyright (c) 1996,97,98,99,2000,01 by Randal L. Schwartz sub __stamp { my ($message) = @_; my $stamp = sprintf "[$$] [%02d@%02d:%02d:%02d] ", localtime[3,2,1,0 +]; $message =~ s/^/$stamp/gm; $message; }` [download] After that, all your output to STDERR (warnings, dies) will be prefixed with the (time)stamp.	[reply] [d/l]
Re: Re: Formatting STDERR by Abigail-II (Bishop) on Feb 12, 2004 at 10:09 UTC
Not really. All your dies and warnings will be formatted (until someone localises $SIG{__WARN__} or $SIG {__DIE__}). It doesn't format anything generated with `print STDERR`. I suggest using IPC::Open3, with "-\|" as the fourth argument. This will fork the process, allowing the parent to read STDERR from the child, and hence you are able to format STDERR they way you want. Abigail	[reply]
Re: Formatting STDERR by leriksen (Curate) on Feb 12, 2004 at 10:11 UTC
Have a look at Filter::Handle and tie's in general +++++++++++++++++ #!/usr/bin/perl use warnings;use strict;use brain;	[reply]
Re: Formatting STDERR by nite_man (Deacon) on Feb 12, 2004 at 10:47 UTC
Try to look at Log::Log4perl - module for control and costomize the loggin behaviour in your applications. It's a port Log4j on Perl. There are many features - loggin levels, logger categories, log messages layouts, dispath log messages to file, on screen, by email etc. Hope it will be helpful! ~ Schiller	[reply]
Re: Formatting STDERR by Roy Johnson (Monsignor) on Feb 12, 2004 at 16:11 UTC
While Filter::Handle looks like the right module for the job, I'd probably just do it by hand as below. If your error output isn't going to be line-based, you should use `select` to poll for input within the child. Season to taste. `my $err_file = "error.log"; open(ERRLOG, "+>>logs/system/$err_file") or die "Could not open logfil +e:$!\n"; flock(ERRLOG,2); # Was STDERR = ERRLOG; my $child = open(STDERR, '\|-'); if ($child < 0) { die "Could not fork: $!\n" } if ($child == 0) { while (<>) { printf ERRLOG '%s %s', scalar(localtime), $_; } exit 0; } print "One\n"; print STDERR "Foo\n"; print "Two\n"; print STDERR "Bar\n"; # and ends with: flock(ERRLOG,8); close(ERRLOG);` [download] The PerlMonk `tr///` Advocate	[reply] [d/l] [select]


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