Patch and diff
This is an "advanced" technique for install scripts to
- Reduce the size of install scripts
- Make them more forward compatible for the future
- Make them more robust
The Idea
The idea is simple: install by hand, make changes to make it work, then compare against the pristine sources, generating a patch that later does automatically what you did by hand
- Setup the app for installation as a webapp (say in html). Save a pristine copy as html.orign
- Make changes in html/ only
- Find out the diff of what you made:
diff -r -N -b -u html.orig html > app-patch.diff
- This then can go into the install script as follows:
patch -p0 -E << EOF
.... contents of app-patch.diff here ....
EOF
Testing the patch ahead of time
It is strongly encouraged that you test the patch before attempting trial-and-error runs in the install script, which can be time consuming and error prone. This is basically simulating the install script applying the patch.
To do this, do this:
mv html html.modified
cp -a html.orig html
mv html.orig html.pristine
(the last step is to prevent patch from accidentally patching html.orig)
then try your patch against html dir (which is now like the original):
patch -p0 -E < app-patch.diff
Doing this will save you a lot of trial-and-error in the installer.
If you have an problems, remove html and then
cp -a html.pristine html
(or unpack the app again and rename it to make the root html/)
