How can I search for a pattern in a log file, and then print the three lines before the line that has the matched pattern? For example:

Log file:

log info line yada yada 1
log info line yada yada 2
log info line yada yada 3
log info line (pattern) 4
log info line yada yada 5
...

[download]

Results file:

log info line yada yada 1
log info line yada yada 2
log info line yada yada 3
(pattern) (Put line number here, or some type of result mark)
...

[download]

Here's the code I'm working with so far.

open(INFILE, "< file.log")
         or die "Cant open file : $!";

open(OUT, "> results.txt")
         or die "Cant open new file : $!";

$pattern = "Error code 2";
    while (<INFILE>) {

    $a[$i++%3] = $_;
    print OUT $a[$i%3]
    if /$pattern/;
}

close INFILE;
close OUT;

[download]

I saw a thread regarding the use of the "%3", but not sure how to use it correctly.

Please let me know how I could produce a result file that pulls the three lines prior to the match of the search string line.

Thank you in advance for any help that can enlighten me

-neurotoxx

In reply to How can I print three lines before pattern match? by neurotoxx

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