# Create patch file

###### tags: `linux`, `patch`

Basic example to use "patch" command.

#### create a patch file

diff -Naur <absolute path of old file > <absolute path of new file>

# create a reverse patch file (just swap new and old file)
diff -Naur <absolute path of  new file> <absolute path of old file>

#### apply a patch file

patch -r- -p0 -d / -N -i <absolute path of patch file>

# create a backup
patch -b -r- -p0 -d / -N -i <absolute path of patch file>

#### reverse a patched file

patch -R <absolute path of patched file> <absolute path of patch file>

Or, use "reverse patch file" to patch.

#### reverse patched file by move backup file (.orig) to the patched file name

for i in *.orig; do
    base=`basename ${i} .orig`
    mv $i $base
done

#### Reference
- https://www.gnu.org/software/diffutils/manual/html_node/Reversed-Patches.html
- https://www.manpagez.com/info/diff/diff_83.php