#! /usr/bin/env bash while read; do KEY="${REPLY%%=*}" VALUE="${REPLY#*=}" if [ "$KEY" = "LoopOnGotoUnread" ]; then case "$VALUE" in [Ff][Aa][Ll][Ss][Ee]|0) echo "LoopOnGotoUnread=0" ;; 2) # we were run already, be nice and don't change anything echo "LoopOnGotoUnread=2" ;; *) # default echo "LoopOnGotoUnread=1" ;; esac else echo "$REPLY" fi done