Linux sed command: How to modify the content of many files

Linux sed FAQ: How can I use the sed command to modify many files at one time?

Here's a Linux/Unix sed command file that I just used to modify a bunch of files:

s/^M//g
1,2d
$d

I put those three lines in a text file named sed.cmds.

After that, I call that sed script from a simple shell script. Here are the contents of the shell script:

#!/bin/sh

# modify every *.txt file in the current directory
for i in `ls *txt`
do
  sed -f sed.cmds < $i > ${i}.new
done

What I'm doing in this shell script is:

1. Getting a list of all files in the current directory that end with the extension "txt".
2. Running my sed command on each file, reading from the original file ($i), and writing to a new file, where the extension ".new" is appended to the end of the original filename.
3. Note that I'm reading the sed command file by using the "-f sed.cmds" argument to the sed interpreter.

Nothing too exciting here, but it is incredibly productive, and I don't want to forget how I did this.

Also note that you can rename your .new files back to .txt files with a mv command, but I'll leave that as an exercise for the reader.

sed on macOS

For information on modifying files in place with sed on macOS, please see this How to use sed to edit files in place tutorial.