Linux/patch

patch and diff

diff from another directory

no built in method, so have to get tricky

Files for test:

• test.original
• test.fixed
• test # target file

Option #1 - move to correct path manually

cd ~/test ; cp test.fixed test
cd .. ; diff -u test/test.original test/test | tee test.patch
#  --- test/test.original  2026-04-21 09:20:42.864135487 -0700
#  +++ test/test   2026-04-21 09:20:56.014023558 -0700

# Then if could be used like:
cp test/test.original test/test
cat test.patch | patch -d . -p0
#  patching file test/test

Option #2 - use the -pX to drop path components

cd ~/test ; cp test.fixed test
diff -u ../test/test.original ../test/test | tee test.patch
#  --- ../test/test.original       2026-04-21 09:20:42.864135487 -0700
#  +++ ../test/test        2026-04-21 09:25:49.926535912 -0700

# Then if could be used like:
cp test.original test
cat test.patch | patch -d .. -p1  # p1 drops first path component
#  patching file test/test
# Alternative would be to edit the patch file and remove the "../" from the header

Option #3 - edit the header

cd ~/test ; cp test.fixed test
diff -u ~/test/test.original ~/test/test | tee test.patch
#  --- /home/USER/test/test.original    2026-04-21 09:20:42.864135487 -0700
#  +++ /home/USER/test/test     2026-04-21 09:31:31.177670259 -0700

# then edit the patch file and fix the header paths
#  --- test/test.original    2026-04-21 09:20:42.864135487 -0700
#  +++ test/test     2026-04-21 09:31:31.177670259 -0700
cp test.original test
cat test.patch | patch -d .. -p0
#  patching file test/test

see also

• patch
• diff