svn switch disaster prevention

svn_safe.sh

#!/bin/bash

### Copyright 2009 Ian Young
### Available under the terms of the MIT license

### ABOUT
### Prevents you from svn switching to a mismatched directory in a different branch.
### See http://blog.iangreenleaf.com/2009/11/avoiding-disaster-when-using-svn-switch.html

### USAGE
### Make sure this file is executable. In your .bashrc or other startup script, add:
### alias svn='/path/to/this_script.sh'

# We only care if it's a switch command
if [[ ( $# = 2 ) && $1 = "switch" ]]
then
        # Get the current path of the working directory we're switching,
        # then filter out the root of the URL
        #
        # Note: We append "=" simply to make sure that sed found a match, since our 
        # filtered path may be empty and we need to distinguish that from no match
        CURRPATH=`svn info | sed -n -e 's_URL: .*/\(trunk\|branches/[^/]*\)/\?\(.*\)_=\2_p'`
        # Now filter the path we're switching to the same way
        NEWPATH=`echo -n "$2" | sed -n -e 's_/\?$__' -e 's_.*/\(trunk\|branches/[^/]*\)/\?\(.*\)_=\2_p'`
        # If we found a match, make sure the paths are the same
        if [[ ( -n "$CURRPATH" ) && ( "$CURRPATH" != "$NEWPATH" ) ]]
        then
                echo "It looks like you're about to make a big mistake."
                exit 1;
        fi
fi

# Otherwise we let SVN carry on with its business

svn "$@";