in reply to Re^2: trouble parsing log file...
in thread trouble parsing log file...

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.

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Re^4: trouble parsing log file...
by perl_geoff (Acolyte) on Nov 20, 2006 at 21:01 UTC
    Ok, now I understand. Here's what I tried, sorry I wasn't more specific. Unfortunately it only displays green: 
    $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

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";

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      The while (<DATA>){ line needs to read 
      while (<LOG>){

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      <DATA> file handle is a "special" one that points to the bit in your script following the __DATA__ marker. This is useful to demonstrate the data associated with code in a forum like this.

      As suggested by others, it is good practice to close your file handle once you are finished with it. 

      close LOG;

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