[Dev] Re: embarrassing patch question

[David Filion]

John F Davis wrote:
> 
> Hello
> 
> Ok.  I've been using patch and I've asked some questions about it on IRC,
> but I'm still not
> sure about how to use it "CORRECTLY" or in the "PRESCRIBED-METHOD".  So,
> please correct me.
> 
> I want to create a patch file to give to my co-workers and instructions on
> how to use it.
> 
> With that said, here is the scenario:
> 
> I have a original directory called foo.orig and a "up-to-date" directory
> called foo.latest.
> So, I created a patch file using this syntax:
> diff -Naur foo.orig foo.latest > foo.patch
> 
> Then to apply the patch, I did:
> patch -p1 foo < foo.patch
> or
> patch -p1 foo.orig < foo.patch
> I can't remember which one I did.
> 
> I think this is right.  However, it would be great if someone would clear
> up the bit
> about the target directory.  Does the target directory have to called the
> same as the
> "patched" or "orig" directory?  Is there a way to specify or edit the patch
> file so
> that the end user can have their own custom directory name.  For instance,
> I used foo and foo.orig, but the end user might have directory names
> like foo2 or foo.nfs, etc.
> 
> JD
> 
> --
> Kernelnewbies: Help each other learn about the Linux kernel.
> Archive:       http://mail.nl.linux.org/kernelnewbies/
> IRC Channel:   irc.openprojects.net / #kernelnewbies
> Web Page:      http://www.kernelnewbies.org/


I threw together something a while ago when I was in the same 
situation, I've included it below.  Because we are using Solaris
at work, it covers the older and newer versions of diff/patch.

HTH
David Filion

--- Start of doc ---

Creating a patch

Below is a cheat sheet for creating and applying patch files.  For more
details about each command, check the commands manpage, info document or
try "command --help".


1.0 Using older versions of diff/patch.
	The older diff/patch utilities don't understand the newer unified 
	format.  Thus, the older conext format must be used. Thus the -c 
	option that appears.

1.1 Create the patch
	diff -c -b -r /original /new > filename.patch

diff options:
	-c  Produces a listing of differences with three lines of context.
	-b  Ignores trailing blanks (spaces and tabs) and treats other strings
	    of blanks as equivalent.
	-r  Applies diff recursively to common subdirectories encountered.

1.2 Apply the patch
	patch -c -l -p1 -d /original < filename.patch

patch options:
	-c  Interpret the patch file as a context difference (the output of
	    the command diff when the -c or -C options are specified).
	-l  Cause any sequence of blank characters in the difference script
	    to match any sequence of blank characters in the input file.  
	    Other characters will be matched exactly.
  	-d  Change the current directory  to  dir  before processing.
	-p NUM  Strip NUM leading components from file names.

2.0 Using newer/GNU diff and patch utilities.
	Unlike their older counterparts, the newer/GNU versions of diff 
	understand the unified format of patch file.  This is the format used
	by the Linux kernel developers.

2.1 Create the patch
	   diff -u oldfile newfile > filename.patch
	or diff -urN /olddir /newdir > filename.patch
	or diff -urN -X excludes /olddir /newdir > filename.patch

diff options:
	-u  Output (default 2) lines of unified context.
	-r  Recursively compare any subdirectories found.
	-N  Treat absent files as empty.
	-X FILE  Exclude files that match any pattern in FILE.

Note: The -u options can be replaced with -c to create a context format diff
      file with a setting of two lines.

2.2 Apply the patch
	   gzip -cd patch.gz | patch -p0
	or bzip2 -dc patch.bz2 | patch -p0
	or patch -p0 < filename.patch

patch options:
	-p NUM  Strip NUM leading components from file names.

3.0 Creating a patch using CVS.
	A patch is created in CVS using the rdiff cvs command.

3.1 Create the patch.
	
	o Create a context (default) format diff of release tags rel1 and 
	  rel2 for module.
	cvs rdiff -r rel1 -r rel2 module

	o Create a unidiff format diff of release tags rel1 and rel2 
	for module.
	cvs rdiff -u -r rel1 -r rel2 module

cvs rdiff options:
	-r tag  Use revision <tag>
	-u  Use the unidiff format.
	-c  Use the context format (default).


Copyright (c) David Filion (filiond@videotron.ca)
Created 2001/09/12.