How to grep '---' in Linux? grep: unrecognized option '---'

linux shell ubuntu grep ubuntu-10.04
Techie picture Techie · Aug 22, 2014 · Viewed 10.2k times · Source

I have a newly installed web application. In that there is a drop down where one option is ---. What I want to do is change that to All. So I navigated to application folder and tried the below command. 

grep -ir '---' .

I end up with below error.

grep: unrecognized option '---'
Usage: grep [OPTION]... PATTERN [FILE]...
Try `grep --help' for more information.

Given that I'm using 

Distributor ID: Ubuntu
Description:    Ubuntu 10.04.4 LTS
Release:    10.04
Codename:   lucid

How to grep '---' in Linux ?

Answer

fedorqui 'SO stop harming' picture fedorqui 'SO stop harming' · Aug 22, 2014

This happens because grep interprets --- as an option instead of a text to look for. Instead, use --:

grep -- "---" your_file

This way, you tell grep that the rest is not a command line option.

Other options:

  • use grep -e (see Kent's solution, as I added it when he had already posted it - didn't notice it until now):

  • use awk (see anubhava's solution) or sed:

    sed -n '/---/p' file

-n prevents sed from printing the lines (its default action). Then /--- matches those lines containing --- and /p makes them be printed.

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