Mass In Place Editing of Linux Configuration Files

Jan 14, 2015 · 1 min read · oneliners Linux

Generally, if I have 100 files that I need to edit and make changes in, I tend to write a perl or python script to make them (if I have 3 files, I just open them in VIM and make them manually!) Yesterday however, a colleague who doesn't code had to change 2 consecutive lines in about 400 similar files and wanted a simple "one liner" type way to do it.

This perl one liner is what I gave him. It allows replacement of multi line text with another piece of multiline text, in place, in the file.

 1$ cat example.conf
 2Line1
 3Line2
 4Line3
 5Line4
 6$ perl -i -la0pe '~s/Line2\nLine3/ReplaceLine2\nReplaceLine3/g' example.conf
 7$ cat example.conf
 8Line1
 9ReplaceLine2
10ReplaceLine3
11Line4

It's then easy to use shell script to loop around all the files in a directory and run this command. If you're nervous, it's best to first check what your changes do by perhaps piping the file through perl.

1$ cat example.conf  | perl -la0pe '~s/Line2\nLine3/ReplaceLine2\nReplaceLine3/g'
2$ cat example.conf 
3Line1
4ReplaceLine2
5ReplaceLine3
6Line4

Another idea is also to use the -i.bak option to make backup files so you have a copy of the files before the edits ;-)