https://unixsheikh.com/tutorials/diff-and-patch.html

A mini tutorial in the usage of diff and patch.

Create the patch file:

$diff -u old-file.txt new-file.txt > changes.diff

Use the patch in order to change old-file.txt to new-file.txt:

$patch old-file.txt changes.diff

Or simply:

$patch < changes.diff

patch will rename old-file.txt to old-file.txt.orig and save the new file with the changes as old-file.txt. old-file.txt is now identical to new-file.txt

If you want to reverse the process you can do it with:

$patch -R old-file.txt changes.diff

Or simply:

$patch -R < changes.diff

diff can also be used to display the difference between content in directories.

$diff /home/user/foo /home/user/bar

If you have any comments or corrections please feel free to email them to me. Also, if you found this content useful consider supporting me on Patreon