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Re^2: Extract lines between two patterns

by mnithink (Initiate)
on Jan 22, 2012 at 07:21 UTC ( #949234=note: print w/ replies, xml ) Need Help??


in reply to Re: Extract lines between two patterns
in thread Extract lines between two patterns

Thanks for the reply First I experimented with this below code on a single file.

perl -ne 'print if /Pattern1/ .. /Pattern2/' file1
This worked for me. But my actual intent is to do this in a loop on multiple files. My code looks as below
#!/usr/bin/perl use strict; use warnings; our $fh; our $log; open($fh,">","file1"); open ($log,">","file2") or die "can not open file $log : $!\n" ; while($fh){ if (/Pattern1 .. /Pattern2/) {printf $log;} }
when i execute this code, i'm getting below message
"Use of uninitialized value in pattern match (m//) at temp.pl line 11. +"


Comment on Re^2: Extract lines between two patterns
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Re^3: Extract lines between two patterns
by philipbailey (Chaplain) on Jan 22, 2012 at 08:39 UTC

    There is nothing much wrong with the code you have posted (with the provisos mentioned below) but the problem appears to be in the pattern(s) in your if statement. The error message indicates that you are using some undefined variable in one or other of the pattern matches in that statement. However, you don't have any variables within the patterns shown--perhaps you should post the actual code?

    A couple of other comments: please put your code in <code> tags--this would make it much more readable. You would probably be better to use lexical (my) rather than package (our) variables in your use case. Finally, you are missing a terminating "/" in the first pattern match, presumably because you have retyped a shortened version of your code. There is nothing wrong with showing PerlMonks a shortened version of your code--in fact it is encouraged--but it needs to be runnable, and demonstrate the bug.

      Thanks for your commnets. I'll try to improve my coding skills. Please find my actual code below.
      #!/usr/bin/perl use strict; use warnings; our $fh; our $log; open($fh,">","block.power"); open ($log,">","temp.log") or die "can not open file $log : $!\n" ; while($fh){ if (/Total Design Power Summary \(Worst/ .. /\|Total/) { printf $log; } }

        Please don't ignore requests to use <code> tags. You can edit your posts and add them. Having posted runnable code, the issues become more obvious: you open file "block.power" for writing, not reading--so use "<", not ">" (and you don't test whether the open succeeds). Your while loop loops infinitely over "$fh", which is always true; you should say while (<$fh>) {, which actually reads from the filehandle. The undefined variable in the pattern match is in fact $_.

        I want to extract lines between Pattern1 and Pattern2 and write it into file2

        untested

        #!/usr/bin/perl use strict; use warnings; our $fh; our $log; open($fh,"<","block.power"); open ($log,">","temp.log") or die "can not open file $log : $!\n" ; while($fh){ if (/Pattern1>(.*?)<Pattern2/) { print $log $1; } } close $fh; close $log;

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