Unix Tip: Scanning your messages file for warnings: Take two

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Several weeks ago, I encouraged readers to automate the extraction of warning messages from their /var/adm/messages (or /var/log/messages) files and provided a script to do just that. In this article, we will look at a re-implementation of that script.



The new version of this script was written by Jared Still, Certifiable Oracle DBA and Part Time Perl Evangelist and author of "Perl for Oracle DBAs". Jared's rewrite of the look4warnings script illustrates how elegantly Perl can be used to extract and summarize the contents of log files.



The first commands in the script rewrite are, more or less, the same as in the original version. We assign our messages file to a variable ($msgs) and attempt to open the file. If we run into problems, we exit, displaying a message like this generated by the die command:

Cannot open /var/log/messages - No such file or directory

The script, then, begins with a comment and the lines to set up our input file.

#!/usr/bin/perl -w

# look through messages file for warnings, show summaries
$msgs="/var/log/messages";

open (MSGS,"<$msgs") || die "Cannot open $msgs - $!\n";

The extraction of all lines containing the word "warning", on the other hand, is accomplished far more simply and elegantly than in the original version. Notice that we accomplished this using a single command.

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