Month: January 2010

Understand Awk Variables with 3 Practical Examples


\"\" This article is part of the on-going Awk Tutorial and Examples series. Like any other programming languages, Awk also has user defined variables and built-in variables. In this article let us review how to define and use awk variables. Awk variables should begin with the letter, followed by it can consist of alpha numeric characters or underscore. Keywords […]

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Quickly search and replace string with Regular expression in multiple files using perl

for i in *; do perl -p -w -e \’s/a(.*)b.*/d$1e/g\’  $i > temp/$i; done

for i in *; do perl -pi -w -e \’s/a(.*)b.*/d$1e/g\’  $i ; done

The first one can be used when you want to preserve the original file. The redirection will cause the file with replaced string to be written to the new location in the temp directory. Modify the same according to your needs.

The second can be used to modify the files in-line. Causing overwriting the original file.

Explanation of the RE : s/a(.*)b.*/d$1e/g

s – substitue

s(.*)b.* –> match anything starting with and store the substring upto b into $1 for further use. Continue matching from b until end of line

d$1e –> replace the original string with d concatened with $1 from the match above and then with e.

grep -v with multiple patterns.

$ sed \'/test/{/error|critical|warning/d}\' somefile If you wanted to do all in one command, you could go w/ sed instead


by David Winterbottom (