Shell Programming and Scripting

#!/bin/bash
# NOTE: This script runs a.sh and b.sh at the same tiem and reports the exit
# status of both before terminating (if either one fails) or moving to to c.sh
# (if both succeed).
# Start a and b...
./bin/a.sh &
pida=$!         # save pid of a.sh
./bin/b.sh &
pidb=$!         # save pid of b.sh

# Reap a...
# NOTE: The following wait will not collect the exit status of b.sh even if
# it finishes first.
wait $pida
esa=$?          # save exit status of a.sh

# NOTE: Following line creates close.log rather than appending to it.  So,
# we get a clean log for each invocation of this script.
# NOTE: There is no need to redirect stderr from these echo commands; the
# only reason for echo to fail would be if there is an error writing to the
# log file (and redirecting that error message to a file that can't be written
# to means that we would get no notification of the error).
echo "a.sh job status : $esa" >close.log
if [ $esa -eq 0 ]
then
        echo "a.sh is success at $(date)" >>close.log
else
        echo "a.sh failed at $(date)" >>close.log
fi