Wildfly start-up script $JBOSS_HOME/docs/contrib/scripts/init.d/wildfly-init-redhat.sh tries to get successful start timestamp using following command:

grep -o '[0-9]*' $JBOSS_MARKERFILE

This however does not work on RHEL 5 OS, as grep-2.5.1 does not return regular expression result correctly when used with -o option.