Replace a string in a file and overwrite the file

Question

I wrote my script using the the directory ~/deleted (it's a long script). after using ~/deleted for the whole script. I want to let the user choose the directory by putting the path in ~/.rm.cfg.

My file starts like this:

#!/bin/bash

defaultpath=~/deleted

if [ -s ~/.rm.cfg ]
then
    defaultpath=$(head -1 ~/.rm.cfg)
fi

I need to replace every ~/deleted with $defaultpath in my script. Is there a way to do it in command line such that it saves and replaces the original file?

I can't get either perl or sed to work.

Answer 1

sed -i 's|~/deleted|"$defaultpath"|g' file.sh

Explanation:

• -i tells sed to modify the file in place.

• s|~/deleted|"$defaultpath"|g tells sed to replace ~/deleted with "$defaultpath" whereever it finds it.

Extra feature: preserve ~/deleted on the third line

You did not ask for this but, in your example script, it would be nice to leave ~/deleted unchanged on the third line where it is used to define defaultpath. To change all instances of ~/deleted except the one on the third line, use:

sed -i -e '3n' -e 's|~/deleted|"$defaultpath"|g' file.sh

This adds the single sed command 3n which tells sed to skip the third line.