Shell Programming and Scripting

#!/bin/ksh
thisFILE="$(whence ${0})"

progNameFull="${0##*/}"
progName="${progNameFull%%.*}"

AWK='/bin/nawk'
FUSER='/usr/sbin/fuser'

#----------------------------------------------------------------------
# see if there's another instance of THIS script running - don't allow MULTIPLE
# instances of the same script running at the same time. If there's a previously
# invoked instance of this script running, log an error message and exit THIS
# current invocation of the script - allow the previously invoked script finish
# its own workload.
     myPID="$$"
     FUSERout=$(${FUSER} ${thisFILE} 2>/dev/null)
     # echo "fuser ->[${FUSERout}]"
     typeset -i numProc=$(echo "${FUSERout}" | ${AWK} '{print NF}')
     if [[ "${numProc}" -gt 1 ]] ; then
        echo "${progName}::main Error: another instance(s) of [${thisFILE}] is currently still running [$(echo ${FUSERout} | sed -e 's/  */ /g')] - exiting THIS [${myPID}] run."
        exit 1
     fi