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Removing a line from a file.

Posted on 2007-11-23
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Last Modified: 2012-05-05
I know this question is everywhere on here - but im missing some detail, either due to brain fart or...  I figured this out a few weeks ago and either deleted it or forgot to document it now i can't seem to figure it out again. Argg - thanks for your help!

Heres the one liner:
perl -i -ne 'print unless /EXP/' file

This prints contents minus the line in the match.

My needs:
1. Needs to be in perl script not a one liner.
2. Needs to remove the line from a file permanently
3. There are 3 columns in the file, we only know the content of one portion of the line.

Example data from dbfile.txt:
12121:someuser_1:domain_1.com
12122:someuser_2:domain_2.com
12123:someuser_3:domain_3.com
12124:someuser_4:domain_4.com
12125:someuser_5:domain_5.com
12126:someuser_6:domain_6.com
12127:someuser_7:domain_7.com
12128:someuser_8:domain_8.com
12129:someuser_9:domain_9.com

The only information we have is domain_5.com so we need to remove that entire line containing that domain.

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Question by:kipper3d
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4 Comments
 
LVL 17

Expert Comment

by:mjcoyne
ID: 20340653
#!/usr/bin/perl -w
use strict;

open (IN, ">dbfile.txt") or die "Couldn't open dbfile.txt: $!\n";
open (OUT, ">dbfile-new.txt") or die "Couldn't open dbfile-new.txt: $!\n";

while (<IN>) {
    print OUT unless (/:domain_5\./);
}
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Accepted Solution

by:
mjcoyne earned 200 total points
ID: 20340655
Sorry --  DO NOT use that script.  It'll clobber your dbfile.txt original.  Here's the corrected version:

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

open (IN, "dbfile.txt") or die "Couldn't open dbfile.txt: $!\n";
open (OUT, ">dbfile-new.txt") or die "Couldn't open dbfile-new.txt: $!\n";

while (<IN>) {
    print OUT unless (/:domain_5\./);
}
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LVL 1

Author Closing Comment

by:kipper3d
ID: 31410710
Thanks mjcoyne,

This wasn't what i had before but it works - so thanks!
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LVL 85

Expert Comment

by:ozo
ID: 20340875
#!/usr/bin/perl
local $^I=".bak";
local @ARGV=("dbfile.txt");
while( <> ){
   print unless /:domain_5\./;
}
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