scripts/edit-sa-prefs

#!/bin/sh
# Copyright (C) 2014, Eric Wong <e@80x24.org>
# License: GPLv3 or later <http://www.gnu.org/licenses/gpl-3.0.txt>
# edit and atomically update ~/.spamasassin/user_prefs safely
set -e
cd ~/.spamassassin
cp user_prefs user_prefs.edit.$$ # don't care if we clobber old files

# non-blocking lock
if ! ln user_prefs.edit.$$ user_prefs.edit
then
	rm user_prefs.edit.$$
	echo >&2 "we are already editing user_prefs.edit"
	exit 1
fi

rm user_prefs.edit.$$

${VISUAL-vi} user_prefs.edit

if diff -u user_prefs user_prefs.edit
then
	rm -f user_prefs.edit
	echo 'no changes'
	exit 0
fi

# check until we're good or $EDITOR fails
while ! spamassassin -p user_prefs.edit --lint
do
	echo >&2 "respawning editor, press Enter to continue"
	read ignored_var
	${VISUAL-vi} user_prefs.edit
done

# atomically replace user_prefs
mv user_prefs.edit user_prefs
echo '~/.spamassassin/user_prefs updated'