diff


How to find differences between two directories using diff

Gotta love diff!

Finding all files and folders that are different in two locations is extremely easy. Using only two parameters we can exhaustively compare two directories, including their sub-directories and produce a list of their differences as such:

diff -qr folder-1/ folder-2/;

The -q parameter instructs diff to print only the files that are different and thus not spam us with thousands of files that are the same.

The -r parameter turns on the recursive feature which instructs diff to check all sub-folders and their files in the two directories under investigation.

Example run:

diff -qr Desktop/source/ /media/tux/My\ Disk/backup\ A/

Files Desktop/source/Camera/20191023_171328.jpg and /media/tux/My\ Disk/backup\ A/Camera/20191023_171328.jpg differ

Files Desktop/source/Camera/VID_20191011_115231.mp4 and /media/tux/My\ Disk/backup\ A/Camera/VID_20191011_115231.mp4 differ

diff: /media/xeirwn//media/tux/My\ Disk/backup\ A/Camera/IMG_20191225_165939.jpg: Input/output error
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Perform diff on two folders

To perform a recursive diff on all the files of two folders we just need to add the -r (or --recursive) parameter that recursively compares any subdirectories found.

To avoid needless messages from the tool, we can also use the -q (or --brief) parameter that reports only when files differ.

Example of performing diff on two folders recursively while preventing needless messages.

diff -rq aFolder someOtherFolder;


How to add untracked files to a git patch

Recently, we had to create a git patch for the deployment of a 3rd party repository in our code.
Some of the changes we had to apply using the patch mechanism was the creation of a few new files.
We did not want to have an external script to copy the new files to the appropriate locations, so we had to include those new files in the git patch somehow.
The git diff command (with the parameter -p or --patch) that generates the patch, it ignored the untracked files and so they did not appear in the patch.
To make the untracked files visible to the git diff command, we staged them (using git add) and then used the following command to create the patch:

git diff --patch --staged;

git diff [--options] --cached [<commit>] [--] [<path>...]
git diff [--options] --staged [<commit>] [--] [<path>...]
Adding the parameter --staged or --cached allows you to view the changes you staged for the next commit relative to the named <commit>. Typically you would want comparison with the latest commit, so if you do not give <commit>, it defaults to HEAD. If HEAD does not exist (e.g. unborned branches) and <commit> is not given, it shows all staged changes. --staged is a synonym of --cached.
From: man git-diff

In the end our commands to create the patch with the new files and apply it on a new clone of the 3rd party repository was as follows:

#In the folder of the modified repository, where the new files are staged
git diff -p --staged > ~/new.file.patch.diff;
#In the folder of the new clone of the repository, where the new files need to be created
git apply ~/new.file.patch.diff;