Today I needed to remove backslashes from a number of files.

I have yaml frontmatter that should look like this:

tags:
  - React.js
  - JavaScript

I had some files that had backslashes before the dash:

tags:
  \- React.js
  \- JavaScript

You can use Unix tools like grep or sed to search all files that match a pattern. Then you can replace that pattern.
But you have to remember that a backslash is a special character. It’s used as an escape hatch to escape other expressions.

Matching a backslash means you have to double it: \\.

That makes search and replace very confusing when you run it from the shell as you have to “double” escape - once for the shell and once for the regex.

Here’s how to search all files in a directory for \ - and delete the backslash in the fish shell:

grep -rl '\\\-' | xargs sed -i 's/\\\//g'

grep -rl runs the search recursively in the current folder and outputs matching files.
xargs pipes the output of grep to sed.
sed -i uses sed to replace the backslash with an empty expression (delete it), inplace.

If you want to use alternative tools [written in Rust][writteninrust]:

rg '\\\-' --files-with-matches | xargs sd '\\\' ''

Or using ruplacer:

ruplacer '\\\\-' '' .

Further Reading