#!/bin/ksh
#
# SCRIPT: proc_watch.ksh
# AUTHOR: Randy Michael
# DATE: 09-12-2007
# REV: 1.0.P
# PLATFORM: Not Platform Dependent
#
# PURPOSE: This script is used to monitor and log
# the status of a process as it starts and stops.
#
# REV LIST:
#
# set -x # Uncomment to debug this script
# set -n # Uncomment to check syntax without ANY execution
#
####################################################
########## DEFINE FILES AND VARIABLES HERE #########
####################################################

LOGFILE="/tmp/proc_status.log"
[[ ! -s $LOGFILE ]] && touch $LOGFILE

PROCESS="$1" # Process to Monitor
SCRIPT_NAME=$(basename $0) # Script Name w/o the PATH
TTY=$(tty) # Current tty or pty

####################################################
############# DEFINE FUNCTIONS HERE ################
####################################################

usage ()
{
    echo "\nUSAGE: $SCRIPT_NAME process_to_monitor\n"
}

####################################################

trap_exit ()
{
    # Log an ending time for process monitoring
    TIMESTAMP=$(date +%D@%T) # Get a new timestamp...
    echo "MON_STOP: Monitoring for $PROCESS ended ==> $TIMESTAMP" \
         | tee -a $LOGFILE

    # Kill all functions
    kill -9 $(jobs -p) 2>/dev/null
}

####################################################

mon_proc_end ()
{
    END_RC="0"
    until (( END_RC != 0 ))
    do
       ps aux | grep -v "grep $PROCESS" | grep -v $SCRIPT_NAME \
              | grep $PROCESS >/dev/null 2>&1

       END_RC=$? # Check the Return Code!!
       sleep 1 # Needed to reduce CPU load!
    done

    echo 'N' # Turn the RUN flag off

    # Grab a Timestamp
    TIMESTAMP=$(date +%D@%T)

    echo "END PROCESS: $PROCESS ended ==> $TIMESTAMP" >> $LOGFILE &
    echo "END PROCESS: $PROCESS ended ==> $TIMESTAMP" > $TTY
}
####################################################

mon_proc_start ()
{
    START_RC="-1" # Initialize to -1
    until (( START_RC == 0 ))
    do
        ps aux | grep -v "grep $PROCESS" | grep -v $SCRIPT_NAME \
               | grep $PROCESS >/dev/null 2>&1

        START_RC=$? # Check the Return Code!!!
        sleep 1 # Needed to reduce CPU load!
    done

    echo 'Y' # Turn the RUN flag on

    # Grab the timestamp
    TIMESTAMP=$(date +%D@%T)

    echo "START PROCESS: $PROCESS began ==> $TIMESTAMP" >> $LOGFILE &
    echo "START PROCESS: $PROCESS began ==> $TIMESTAMP" > $TTY
}

####################################################
############## START OF MAIN #######################
####################################################

### SET A TRAP ####

trap 'trap_exit; exit 0' 1 2 3 15

# Check for the Correct Command Line Argument - Only 1

if (( $# != 1 ))
then
     usage
     exit 1
fi

# Get an Initial Process State and Set the RUN Flag

ps aux | grep -v "grep $PROCESS" | grep -v $SCRIPT_NAME \
       | grep $PROCESS >/dev/null

PROC_RC=$? # Check the Return Code!!

# Give some initial feedback before starting the loop

if (( PROC_RC == 0 ))
then
     echo "The $PROCESS process is currently running...Monitoring..."
     RUN="Y" # Set the RUN Flag to YES
else
     echo "The $PROCESS process is not currently running...Monitoring..."
     RUN="N" # Set the RUN Flag to NO
fi

TIMESTAMP=$(date +%D@%T) # Grab a timestamp for the log

# Use a "tee -a $#LOGFILE" to send output to both standard output
# and to the file referenced by $LOGFILE

echo "MON_START: Monitoring for $PROCESS began ==> $TIMESTAMP" \
      | tee -a $LOGFILE

# Loop Forever!!

while :
do
     case $RUN in
     'Y') # Loop Until the Process Ends
          RUN=$(mon_proc_end)
          ;;
     'N') # Loop Until the Process Starts
          RUN=$(mon_proc_start)
          ;;
     esac
done

# End of Script