AIX

###################################################################################
# Is this job already running
###################################################################################
[[ $VERBOSE -ge $TRUE ]] && print_status_message "STEP: Checking to see if this job is already running..." STEP

RUNNING=$FALSE
LOOP_COUNT=1
MAX_LOOP_COUNT=5

[[ $DEBUG -ge $TRUE ]] && print_status_message "DEBUG: PROGRAM_NAME=$PROGRAM_NAME" DEBUG
[[ $DEBUG -ge $TRUE ]] && print_status_message "DEBUG: STARTDIR=$STARTDIR" DEBUG
[[ $DEBUG -ge $TRUE ]] && print_status_message "\nDEBUG: my PID is: $$" DEBUG
[[ $DEBUG -ge $TRUE ]] && print_status_message "DEBUG: count of running processes..." DEBUG
[[ $DEBUG -ge $TRUE ]] && ps -ef | egrep -v "run_job|timeout|grep|$$" | grep "$PROGRAM_NAME" | grep -c $STARTDIR

sleep 1                                         # this seems to be necessary

while [[ $(ps -ef | egrep -v "run_job|timeout|grep|$$" | grep "$PROGRAM_NAME" | grep -c $STARTDIR) -gt 0 && $LOOP_COUNT -le $MAX_LOOP_COUNT ]]
do
   RUNNING=$TRUE

   print_status_message "INFORMATION: it looks like $PROGRAM_NAME is already running against $STARTDIR. Attempt $LOOP_COUNT of $MAX_LOOP_COUNT." INFORAMTION

   [[ $DEBUG -ge $TRUE ]] && print_status_message "\nDEBUG: output from ps is:" DEBUG
   [[ $DEBUG -ge $TRUE ]] && ps -ef | egrep -v "run_job|timeout|grep|$$" | grep "$PROGRAM_NAME" | grep $STARTDIR

   [[ $DEBUG -ge 2 ]] && print_status_message "\nDEBUG: output from ps is:" DEBUG
   [[ $DEBUG -ge 2 ]] && ps -ef | egrep -v "run_job|timeout|grep|$$" | grep "$PROGRAM_NAME"

   [[ $DEBUG -ge 2 ]] && print_status_message "\nDEBUG: output from ps (ps -ef | egrep -v run_job|timeout|grep|$$) is:"  DEBUG
   [[ $DEBUG -ge 2 ]] && ps -ef | egrep -v "run_job|timeout|grep|$$"

   [[ $DEBUG -ge 3 ]] && print_status_message "\nDEBUG: output from ps is:"  DEBUG
   [[ $DEBUG -ge 3 ]] && ps -ef | grep "$PROGRAM_NAME"

   ((LOOP_COUNT += 1))

   sleep $(($RANDOM % 21 + 1))                                          # random number between 1 and 21

done


if [[ $RUNNING -eq $TRUE && $LOOP_COUNT -ge $MAX_LOOP_COUNT ]]
then
   print_status_message "\nERROR: giving up after $MAX_LOOP_COUNT tries." ERROR
   RETCODE=102
   error_exit

fi

#! /bin/ksh

typeset -i iProcNr="$$"                           # our own process nr
typeset    fPIDFile="/some/procfile.pid"

if [ -f "$fPIDFile" ] ; then
     print -u2 "ERROR: script already running, exiting."
     exit 1
else
     print - "$iProcNr" > "$fPIDFile"
fi

.... here goes the rest of your code ....

rm -f "$fPIDFile"
exit 0