Unix Command to Find And Replace Text in a File

The following is a very simple, one-line command for finding and replacing all instances of a text pattern in a file (or files). There are numerous sources for this short script. It may seem completely trivial, but it comes in handy.

• perl -pi -e 's/<find>/<replace>/' FILE_1 FILE_2 ... FILE_n
  

This will only replace the first occurrence of the pattern per line. If you want to replace all occurrences in every line, then add the 'g' option, like this.

• perl -pi -e 's/<find>/<replace>/g' FILE_1 FILE_2 ... FILE_n
  

If you want the find to be case-insensitive, then use the 'i' option, like this.

• perl -pi -e 's/<find>/<replace>/i' FILE_1 FILE_2 ... FILE_n
  

If you find that you need to replace file path names in text, then instead of back-slashing all the path separators in your pattern, you might want to choose a different s/// separator. I have found that '~' works pretty well (but if your paths contain '~'s, then you should experiment).

• perl -pi -e 's~/path/to/my/file~/new/path/to/file~' FILE_1 FILE_2 ... FILE_n

If you want to replace some text with the contents of an environment variable, then you can access the environment with the hash ENV.

• perl -pi -e 's~some_text~$ENV{environment_variable}~' FILE_1 FILE_2 ... FILE_n

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