Ignore the list building and just work through the file line by line and use a regular expression to test.

Take a look at the following as an example.

use strict;

# Set the button to green initially
my $button = "perlgreenblink";

# test the file line by line.
# The line gets read into $_
# I am testing on the DATA segment to illustrate the point
while (<DATA>){
    
    # test with a regex and end the 
    # while loop if there is a problem
    if (/DOWN/){
        $button = "perlredblink2";
        last;
    }
    
    if (/PROBLEM/){
        $button = "perlyellowblink";
        last;
    }
}

print "HTML for <img src=\"$button.gif\" />\n";


__DATA__
nothing here
going smoothly
Its all going DOWN
no PROBLEM at all
[download]

Ok, I tried this, but could only get it to display the green button...also, I'm not sure I understand the logic of setting the button to green first. When I run your script it seems to ignore everything but the last line. Also, I don't believe any of my log files are above about 5 mb or so.

The logic is that you are testing the log file for a specific condition. You create a starting condition that assumes that everything has gone well and would result in a green button. The idea is that if you get to the end of the file without hitting one of your two tests then everything was OK.

You read the file one line at a time looking for either DOWN or PROBLEM. When one of these tests work, you set the button response accordingly and use last to leave the while loop and do something with the outcome.

You may only be reading 5Mb of files but this translates into a much larger use of memory. It also involves the computer reading the file line by line anyway as it puts it into memory. If your match is on line 20 of a 2000 line file, your script only needs to read 20 lines and you are done.

If you continue to have trouble, post your code in the replies.

You are trying to compare a list against a scalar in this line:

if (@logarray eq $error) {
[download]

What I suspect you want to do instead is to iterate through the list, and break out of the loop when you find the condition you're looking for (note that you don't need to quote variable names to print them):

chomp @logfile;
my $got_button = 0;
foreach my $line (@logarray) {
    if ($line eq $error) {
        $got_button = 1;
        print $redbutton;
        last;
    } elsif ($line eq $warn) {
        $got_button = 1;
        print $yellowbutton;
        last;
    }
}
if (not $got_button) {
    print $greenbutton;
}
[download]

The above will look through each line read in from the file, and print $redbutton or $yellowbutton if the appropriate string is matched.

I also did a chomp @logfile to remove the newline from each logfile line, so that the match doesn't have to explicitly declare it.

Also, the variable got_button was used so that, when you've gone through all the lines from the file, if the match wasn't found, you know to display the $greenbutton.

Hope that helps!

Well, if you're looking for a pattern instead of an exact string, you can look into regular expressions.

For example, to match the string "server is DOWN" anywhere in the line:

    if ($line =~ /server is DOWN/) {
        $got_button = 1;
        print $redbutton;
        last;
    }
[download]

... and you can ignore case (eg. match "Server IS down" and "SERVER is Down" both) by adding i at the end:

    if ($line =~ /server is DOWN/i) {
        $got_button = 1;
        print $redbutton;
        last;
    }
[download]

But definitely look into regular expressions, which will open up a whole world for you in terms of pattern-matching power.

---

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

Thanks, I am about halfway through ch.8 'matching with regular expressions' in my learning perl book. Ok, I tried the following:

$logfile="log.txt";
$error=(/DOWN/);
$warn=(/PROBLEM/);
$redbutton="\<img src\=\'default_files/perlredblink2\.gif'>";
$greenbutton="\<img src\=\'default_files/perlgreenblink\.gif'>";
$yellowbutton="\<img src\=\'default_files/perlyellowblink\.gif'>";

open LOG, $logfile or die "Cannot open $logfile for read :$!";

@logarray=<LOG>;   # dumps all of $logfile into @logarray

chomp @logfile;
my $got_button = 0;
foreach my $line (@logarray) {
    if ($line eq $error) {
        $got_button = 1;
        print $redbutton;
        last;
      }
     elsif ($line eq $warn) {
        $got_button = 1;
        print $yellowbutton;
        last;
    }
  }
if (not $got_button) {
    print $greenbutton;
}
[download]

But it still only displays the green button!

EDIT: Success! I got it now, thanks for your help everyone!

use warnings;

$logfile="log.txt";
$error="DOWN";
$warn="PROBLEM";
$redbutton="\<img src\=\'default_files/perlredblink2\.gif'>";
$greenbutton="\<img src\=\'default_files/perlgreenblink\.gif'>";
$yellowbutton="\<img src\=\'default_files/perlyellowblink\.gif'>";

open LOG, $logfile or die "Cannot open $logfile for read :$!";

my $button = $greenbutton;

while (<LOG>) {
if ($_ =~ /$error/i) {
  $button = $redbutton;
  print "<!--Content-type: text/html-->\n\n";
     print "$redbutton";
  }
if ($_ =~ /$warn/i) {
  $button = $yellowbutton;
  print "<!--Content-type: text/html-->\n\n";
     print "$yellowbutton";
  }
}
close LOG;
[download]

This looks good logically, but I can only get it to display green again...my logfile specifically says "server is DOWN." Oh well, I will keep hackin around... :)

use File::Tail;

 tie *LOG, 'File::Tail', (name => $logfile, tail => -1)
    or die("log open error: $!");

 while (my $line = <LOG>) {
   if ($line eq $error) { print $redbutton; }
   # etc
 }
 close (LOG)
    or die("log close error: $!");
[download]

Hi, I am new to using modules, can you give me more information on how to install/get File::Tail? Thanks!

A Guide to Installing Modules

One other small point that others seem to have missed....
You probably don't want to break out of your while loop if you find a "PROBLEM". That is because there may be a "DOWN" further on in the logfile which you would then miss.

ie. you should not have a last; in the if ($line =~ /$warn/) condition (or however you end up writing it).

Cheers,
Darren :)

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