swilhelm73 has asked for the wisdom of the Perl Monks concerning the following question:

I've got a log file I am trying to parse with Perl. Basically I want to select two lines and then concatenate to print out both values on one line.

What I have so far;

#!/usr/bin/perl -w
#use strict;

my $line1=$_;

$LOGFILE="Output.txt";
open(LOGFILE) or die("Could not open Output.txt.");
foreach $line1(<LOGFILE>) {
if ($line1 =~ m/^Start/)
{
$time = $line1;
}
elsif ($line1 =~ m/^Response\s+Time\s+\(avg\):\s+([0-9.]+)/)
{
$response = $line1;
}
{print join $time, $response}
}

[download]

The problem is that I am grabbing each line separately so my result is of the format:

Start: Blah
Response Time Blah

when I want
Start: Blah Response Time Blah

The Response Time line is always 8 lines below the Start line, so I think I could set both variables at the same time if I knew how to tell Perl to search 8 lines below the match.

Replies are listed 'Best First'.
Re: Simple Parsing Script
by roboticus (Chancellor) on Apr 23, 2012 at 19:24 UTC

    swilhelm73:

    If it's always 8 lines after the start line, then go ahead and read a record of 8 lines when you detect start, and then process them as a group:

    if ($line1 =~ m/^Start/) {
    # Append the rest of the record
    $line1 .= <LOGFILE> for 1..7;
}

    [download]

    If you care only about the first and last lines, though, you could just skip the intervening lines:

    if ($line1 =~ m/^Start/) {
    # Skip to the end of the record
    my $t = <LOGFILE> for 1..6;
    my $lastline = <LOGFILE>;
}

    [download]

    However, if you simply chomp your input line for the start record, you'll get the single line you want. Note: Some people (myself included) find it more convenient to remove all whitespace from the end of lines using $line =~ s/\s+$//; or equivalent.

    ...roboticus

    When your only tool is a hammer, all problems look like your thumb.

[reply]
[d/l]
[select]
Re: Simple Parsing Script
by toolic (Bishop) on Apr 23, 2012 at 19:22 UTC
[reply]
[d/l]
Re: Simple Parsing Script
by 2teez (Vicar) on Apr 23, 2012 at 20:04 UTC

    Going through your log file with a simple while loop could do this, where any match is attached to a string variable. Check the code below 

    #!/usr/bin/perl
use warnings;
use strict;

my $msg      = "";
my $log_file = "Output.txt";
open my $fh, '<', $log_file or die "can't open file: $!";
while ( my $line = <$fh> ) {
    chomp $line;
    if ( $line =~ /^\bstart.+?/i ) {
        $msg .= $line. ' ';
    }
    elsif ( $line =~ /^\bresponse.+?$/i ) {
        $msg .= $line. $/;
    }
    else { next; }
}
close $fh or die "can't close file:$!";

print $msg;

    [download]
[reply]
[d/l]
      Tweaking the response search term (there is another line with response in it) does the trick. THANK YOU!
[reply]

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