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Editorial Team
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Asked: 2026-05-15T15:41:11+00:00

I’m trying to write a bash script that can edit itself. The line of

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I’m trying to write a bash script that can edit itself. The line of code I’m trying to use is:

sed "s/$STRING_TO_REPLACE/$NEW_STRING/" < $0 > $0

But after running the script I end up with an empty file. Any suggestions?

I am creating a script that has two variables that contain default values. The only problem is, these default values will be different for each of the many stations where it will be used. I would rather none of the people running these stations had to open the script and edit the defaults themselves, so I want to include the ability to change the defaults in the script. One of the requirements I have is that the script must be self contained; no other files are to accompany the script and there are to be no environment variables. This would require the script to be able to edit itself.

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1 Answer

  1. Editorial Team

    If you want to do an in-place substitution with sed, use the -i switch.

    I wouldn’t recommend re-writing the currently executing script on the fly. I’m not sure whether it’s possible or not, but if it is, it would certainly be interesting (read: difficult) code to maintain 🙂

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