Wednesday 21 May 2008 — This is more than 16 years old. Be careful.
Occasionally I write things here simply so that I won’t forget them, here’s one of them. Applying patches is something I do infrequently enough that I have to re-figure it out each time.
If you have a patch file called my.patch that looks like this (in part):
=== modified file 'cogapp/cogapp.py'
--- cogapp/cogapp.py 2005-12-04 20:27:41 +0000
+++ cogapp/cogapp.py 2008-05-21 09:00:08 +0000
@@ -37,6 +37,7 @@
A %s in the CMD will be filled with the filename.
-x Excise all the generated output without running the generator
-z The [[[end]]] marker can be omitted, and is assumed at eof.
+ -N Write the output as binary file (with LF line-endings).
-v Print the version of cog and exit.
-h Print this help.
"""
then to apply the patch, cd to the directory that has cogapp in it, and use this command:
patch -p0 < my.patch
The patch command is one of those inscrutable Unix-culture tools which does not behave as I expect. In this case, there seems to be no syntax that names my.patch explicitly, only an input redirect works. And zero seems not to be the default for the -p switch, so it needs to be specified, but the help text doesn’t mention the default value, so I’m not sure what it is.
Comments
patch -p0 -i my.patch
jitter:~ emurphy$ bzr help patch
Purpose: Apply a named patch to the current tree.
Usage: bzr patch [FILENAME]
-pnum or --strip=num
Strip the smallest prefix containing num leading slashes from each file name found in the patch
file. A sequence of one or more adjacent slashes is counted as a single slash. This controls how
file names found in the patch file are treated, in case you keep your files in a different direc-
tory than the person who sent out the patch. For example, supposing the file name in the patch
file was
/u/howard/src/blurfl/blurfl.c
setting -p0 gives the entire file name unmodified, -p1 gives
u/howard/src/blurfl/blurfl.c
without the leading slash, -p4 gives
blurfl/blurfl.c
and not specifying -p at all just gives you blurfl.c. Whatever you end up with is looked for
either in the current directory, or the directory specified by the -d option.
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