Fetchmail for all users

#!/bin/bash

# This script runs fetchmail for every user who has a .fetchmailrc in his home folder
# and whose home-folder is in /home (so not system accounts).
# fetchmail is started as the user, so running this script as root isn't a problem.
# I have it in my crontab to run every 5 minutes.
# If a user already has a running fetchmail-instance, the user is skipped this time.

for fetchmailrc in /home/*/.fetchmailrc
do
        user=${fetchmailrc/\/home\/}
        user=${user/\/.fetchmailrc}
        ps=$(ps -u "$user" | grep fetchmail)

        if [ -z "$ps" ]
        then
                echo "Doing fetchmail for user '$user' ..."
                su -c "cd; fetchmail > .fetchmail.log" "$user"
                echo
                echo "Output of fetchmail:"
                cat "/home/$user/.fetchmail.log"
        else
                echo "fetchmail already running for user '$user'"
                echo "ps output: $ps"
        fi

        echo
        echo
done