Use sed to replace string in several files or several strings in a file

08 August 2019

I used ‘sed’ not so often but each time it is a nice wonder to realize what you can do with it.

I am on Windows and I am using Gow to use such tool from linux (like grep, ls, and so on) with the cmd console.

You can do a lot of things with this tool that I will not explain (because actually I know really litle, but you can find a lot on the web).

The actual scenario I had was a logfile with several lines that I add to change.

I had to filter which line I wanna change and to just change the part I need so for each line I had a sed command like this one :

sed -i -E "s/(.+)S=2:C=4(.+)BAR CODE READ, NOCODE(.+)/\1S=2:C=4\2BAR CODE READ, AP0001\3/g" *


  • sed -i
  • -E (for regular expression)
  • ”s/
  • (.+) (All character, group 1)
  • S=2:C=4
  • (.+) (All character, group 2)
  • (.+) (All character, group 3)
  • /
  • \1 (Past group 1)
  • S=2:C=4
  • \2 (Past group 2)
  • \3 (Past group 3)
  • /g” *

Was changing this [2019/08/07 11:11:33] INFO: [S=2:C=4(LDV384):I=32(sbcr):Q=50:M=2] DATA, BAR CODE READ, NOCODE^M in this [2019/08/07 11:11:33] INFO: [S=2:C=4(LDV384):I=32(sbcr):Q=50:M=2] DATA, BAR CODE READ, AP0001^M

I was using 1 sed cmd per substitution because I had a lot of NOCODE to substitute in the same file so I had to be sure I am picking the right line to work on.

Parameter -E is meaning that Regex Expression is used.


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