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

I'm setting up a virtual hosting environment with mod_vhost_alias, so I've got to manually split up log files for each client. I figured that would be really simple, and discovered that it was. All I had to do was write a script that takes input on STDIN and have it do what I need to. The Apache group has split-logfiles which theoretically does this. But I'm running into a peculiar problem. When I put it into my Apache log files with: 
CustomLog "|/opt/apache/logs/split-logfiles" combined

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It opens each file that it is supposed to, but then none of the log entries get written. I decided to do some testing of my own and wrote this: 
#!/usr/bin/perl
$isopen = 0;
while ($log_line = <STDIN>) {
    $myfile = "/var/tmp/test.log";
    unless($isopen and -f $myfile) {
      open MYHAPPYFILE, ">$myfile" or die "Error opening $myfile";
      $isopen = 1;
    }

    printf MYHAPPYFILE "%s", $log_line;
}
exit 0;

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And when I put that into apache instead of split-logfiles, it does the same thing: /var/tmp/test.log gets created but none of the log entries get put into it. When I tried printing to STDERR instead of MYHAPPYFILE, it showed up fine in the error log. Any ideas?

Replies are listed 'Best First'.
Re: Apache log pipe doesn't write to log files
by trs80 (Priest) on Nov 10, 2002 at 06:57 UTC
    I haven't tested this, but this is how I would write it based on what you have provided. 
    #!/usr/bin/perl
use strict;

# split-logfiles

# you don't need to test if it is open
#$isopen = 0;

my $myfile = "/var/tmp/test.log";

# no reason to do this testing
#    unless($isopen and -f $myfile) {

# open the happy file here, but you may want to use >> if
# you need to append rather then overwrite on each run
open MYHAPPYFILE, ">$myfile" or 
    die "Error opening $myfile";

# don't need to test if it is open because we 
# are dying if it isn't
#      $isopen = 1;
#    }

while (my $log_file = <STDIN>) {
    printf MYHAPPYFILE "%s", $log_line;
}
exit 0;

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    And without commments: 
    #!/usr/bin/perl
use strict;

my $myfile = "/var/tmp/test.log";

open MYHAPPYFILE, ">$myfile" or 
    die "Error opening $myfile";

while (my $log_file = <STDIN>) {
    printf MYHAPPYFILE "%s", $log_line;
}

exit 0;

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Re: Apache log pipe doesn't write to log files
by chromatic (Archbishop) on Nov 10, 2002 at 06:52 UTC

    Are the files completely empty, or is there a blank line? You're overwriting the combined log file, not appending to it, which may be part of the problem. You will also run into trouble if a line evaluates to false. I'd probably write: 

    open( my $fh, '>>', '/var/tmp/test.log' ) or die "Cannot open file: $!
+\n";
select $fh;
print while <STDIN>;

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    That's untested, and it requires Perl 5.6.0 or better.

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Re: Apache log pipe doesn't write to log files
by SamQi (Beadle) on Nov 10, 2002 at 06:07 UTC
    It should also be noted that if I run this on the command line: 
    $ cat my_normal_log_file | ./split-logfiles

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    it works just fine.
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[d/l]

      Try closing your ouput file before you exit.

      Nah! You're thinking of Simon Templar, originally played (on UKTV) by Roger Moore and later by Ian Ogilvy
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[reply]
        I feel so bright now. I turned off buffering, and it worked just fine. Thanks!
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