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Applying Patches in Other Directories

The '-d directory' or '--directory=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 news reading program, you can patch a file in the '/usr/src/emacs' directory directly from the article containing the patch like the following example:

| 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 '-p[number]' or '--strip[=number]' 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. '-p' with no numbergiven is equivalent to '-p0'. By default, patch strips off all leading directories, leaving just the base file names, except that when a file name given in the patch is a relative file name and all of its leading directories already exist, patch does not strip off the leading directory. (A relative file name is one that does not start with a slash.)

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. For example, suppose the file name in the patch file is '/GNU/src/emacs/etc/NEWS'. Using '-p' or '-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'.