$ curl cheat.sh/
 cheat:patch 
# To patch one file:
patch <file> < <patch-file>

# To reverse a patch:
patch -R <file> < <patch-file>

# To patch all files in a directory, adding any missing new files:
# -p strips leading slashes
$ cd dir
$ patch -p1 -i <dir> <patch-file>

# To patch files in a directory, with one level (/) offset:
patch -p1 -r <dir> < <patch-file>

 tldr:patch 
# patch
# Patch a file (or files) with a diff file.
# Note that diff files should be generated by the `diff` command.
# More information: <https://manned.org/patch>.

# Apply a patch using a diff file (filenames must be included in the diff file):
patch < patch.diff

# Apply a patch to a specific file:
patch path/to/file < patch.diff

# Patch a file writing the result to a different file:
patch path/to/input_file -o path/to/output_file < patch.diff

# Apply a patch to the current directory:
patch -p1 < patch.diff

# Apply the reverse of a patch:
patch -R < patch.diff

$
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