ex-19-02_timer.sh

Berkely的学生写的

#!/bin/sh
# Chapter 19 - Working with Signals
# This script demonstrates how to catch and send signals
#
# Define the variable $PROG in your environment and then
# execute this script to see the time in action

AlarmHandler() {
    echo "Got SIGALARM, cmd took too long."
    KillSubProcs
    exit 14
}

KillSubProcs() {
    kill ${CHPROCIDS:-$!}
    if [ $? -eq 0 ] ; then echo "Sub-processes killed." ; fi
}

SetTimer() {
    DEF_TOUT=${1:-10};
    if [ $DEF_TOUT -ne 0 ] ; then
        sleep $DEF_TOUT && kill -s 14 $$ &
        CHPROCIDS="$CHPROCIDS $!"
        TIMERPROC=$!
    fi
}

UnsetTimer() { 
    kill $TIMERPROC 
}

# main()

trap AlarmHandler 14

SetTimer 15
$PROG &
CHPROCIDS="$CHPROCIDS $!"
wait $!
UnsetTimer
echo "All Done."
exit 0