I am trying to write a script that searches for the string ERROR in a log and print that line as well as the line above it to a CSV file. However, I am not sure how to get the line directly above the error line to print. Here is my code. 
open (DIFFR, "/tmp/log.diff");
while (<DIFFR>) {
$line=$_;    #read first line
chomp($line);

if ($line =~ /ERROR/) {
print CSVFILE "$line,";
}

[download]
The reason is that the ERROR line has pertinent info the line directly above it in the log file. Here is some sample data: 
2004.12.01 20:00:49.307 Agent.AgentLOG saveToSYS_AGENT_RUN_LOG()      
  ourhost(10.10.52.36) ERROR:  ********* memo == *** End Execution

[download]

In reply to need to extract top and bottom lines... by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.