Bash/sed - use sed in variable

Question

I would like to use sed to delete and replace some characters in a bash script.

#!/bin/bash
DIR="."
file_extension=".mkv|.avi|.mp4"
files= `find $DIR -maxdepth 1 -type f -regex ".*\.\(mkv\|avi\|mp4\)" -printf "%f\n"`

In order to simplify $files, I would like to use $file_extension in it, ie change.mkv|.avi|.mp4 to mkv\|avi\|mp4

How can I do that with sed? Or maybe an easier alternative?

Answer 1

No need for sed ; bash has basic substitution operators built in. The basic syntax for a replace-all operation is ${variable//pattern/replacement} , but unfortunately it can't be nested so you need a helper variable. For clarity, I'll even use two:

file_extension_without_dot="${file_extension//./}"           # mkv|avi|mp4
file_extension_regex="${file_extension_without_dot//|/\\|}"  # mkv\|avi\|mp4
files= `find $DIR -maxdepth 1 -type f -regex ".*\.\($file_extension_regex\)" -printf "%f\n"`

If your find supports it, you could also consider using a different -regextype (see find -regextype help ) so you don't need quite so many backslashes anymore.