gistfile1.txt

#!/bin/bash

configfile='/tmp/myconfig.cfg'
configfile_secured='/tmp/myconfig_secured.cfg'

# check if the file contains something we don't want
if egrep -q -v '^#|^[^ ]*=[^;]*' "$configfile"; then
	echo "Config file is unclean, cleaning it..." >&2
	# filter the original to a new file
	egrep '^#|^[^ ]*=[^;&]*' "$configfile" > "$configfile_secured"
	configfile="$configfile_secured"
fi

# now source it, either the original or the filtered variant
source "$configfile"