diffutils: patch Directories
10.7 Applying Patches in Other Directories
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The '--directory=DIRECTORY' ('-d DIRECTORY') option to 'patch' makes
directory DIRECTORY the current directory for interpreting both file
names in the patch file, and file names given as arguments to other
options (such as '-B' and '-o'). For example, while in a mail reading
program, you can patch a file in the '/usr/src/emacs' directory directly
from a message containing the patch like this:
| patch -d /usr/src/emacs
Sometimes the file names given in a patch contain leading
directories, but you keep your files in a directory different from the
one given in the patch. In those cases, you can use the
'--strip=NUMBER' ('-pNUMBER') option to set the file name strip count to
NUMBER. The strip count tells 'patch' how many slashes, along with the
directory names between them, to strip from the front of file names. A
sequence of one or more adjacent slashes is counted as a single slash.
By default, 'patch' strips off all leading directories, leaving just the
base file names.
For example, suppose the file name in the patch file is
'/gnu/src/emacs/etc/NEWS'. Using '-p0' gives the entire file name
unmodified, '-p1' gives 'gnu/src/emacs/etc/NEWS' (no leading slash),
'-p4' gives 'etc/NEWS', and not specifying '-p' at all gives 'NEWS'.
'patch' looks for each file (after any slashes have been stripped) in
the current directory, or if you used the '-d DIRECTORY' option, in that
directory.