better miniscoping rules: the premise C~={} is not good
because Safe_tac eliminates such assumptions.
#!/bin/bash
#
# $Id$
#
# showtime - print time.
TIME=$1
SECS=$[ $TIME % 60 ]
[ $SECS -lt 10 ] && SECS=0$SECS
MINUTES=$[ ($TIME / 60) % 60 ]
[ $MINUTES -lt 10 ] && MINUTES=0$MINUTES
HOURS=$[ $TIME / 3600 ]
echo "${HOURS}:${MINUTES}:${SECS}"