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= How to Patch a Port on Your System =

 * Audience: People who want to change the code of an existing port
 * Requires: MacPorts >= 2.1.2?

== Introduction ==

If you've ever found a port that doesn't work, then found a patch for it with Google, the next step is to apply the patch to the source code, then compile, test, and install the new version of the port so you can use it and get on with your work.  This HOWTO will show you how to do that.  In this example, I'll be using the 'arb' program as an example.

== Installation ==

=== Step 1: '''Set up a local repository''' ===

If you want to make changes that stick and won't be overwritten by accident, you need to set up a local
repository, described in full here: http://guide.macports.org/#development.local-repositories

Do this to create a new Port (as root):
{{{
umask 022
mkdir -p /usr/local/ports/
cd /usr/local/ports
cp -r `port dir arb` .
mv arb arb-devel
}}}

Add this line before the 'rsync://.......' line in /opt/local/etc/macports/sources.conf, at the end of the file:
{{{
file:///usr/local/ports
}}}

Then run this command:
{{{
portindex   # Not working for me...?
}}}

=== Step 2: '''Get your port's sourcecode''' ===

{{{
port patch arb-devel
cd `port work arb-devel`
}}}

=== Step 3: '''Modify the source with your patch''' ===

{{{
cp Makefile Makefile.orig
vi Makefile
* make changes, compile it, test it *
}}}

=== Step 4: '''Make a patch''' ===

See http://guide.macports.org/#development.patches.source
{{{
diff -u Makefile.orig Makefile > /usr/local/ports/arb/files/patch-ARB-makefile2.diff
port edit arb-devel     (add the patch-ARB-makefile2.diff file to the list of patches)
}}}

=== Step 5: '''Test the modified port''' ===

{{{
port clean arb-devel
port build arb-devel
}}}

=== Step 6: '''Make it real''' ===

{{{
port install arb-devel
}}}

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