Bash script to control execution of a game (time played, etc). It only allows the game to be played between certain hours and also tracks the total time in a day that has been played, killing the game if either condition is surpassed.

mahjongg.control.sh

#!/bin/bash

#set up constants
TIME1=12    #start hour (24 hour clock)
TIME2=20      #end hour (24 hr clock)
TIMELIMIT=60  #mintues
PGMNAME="mahjongg"  #exact name used for killall and for TIMEFILE
PGMPATH="/usr/games/$PGMNAME"
TIMEFILE="$HOME/.local/$PGMNAME.elapsed"
STARTTIME=`date +%s`  #seconds since 0000 UTC

#functions (Bash functions are really limited -- should have used PERL)
## This function calculates the time spent playing the game
## and updates the ELAPSED variable and the TIMEFILE contents.
## Converting seconds to minutes truncates instead of rounding so add 29 seconds
#XX Problem - this increases the number of minutes faster that it should be.
#XX Fixed. This should really be changed to track seconds played, not TIMELIMIT in minutes.
function updateTime () {
   ENDTIME=`date +%s`
   local minutes #local variables must be declared before initialization
   #minutes=$((($ENDTIME - $STARTTIME + 29)/60))
   #minutes=$((($ENDTIME - $STARTTIME)/60))
   #ELAPSED=$(($ELAPSED + $minutes))
   ELAPSED=$(($ELAPSED + 1))
   echo -e "minutes=$minutes\telapsed=$ELAPSED" >> $HOME/mj.log
   echo $ELAPSED > $TIMEFILE
}


if [ ! -f $TIMEFILE ]; then
   echo 0 > $TIMEFILE
fi
ELAPSED=`cat $TIMEFILE`

#check if time is within permitted hour range
HOUR=$(date +%H)
if [ "$HOUR" -lt $TIME1 -o "$HOUR" -ge $TIME2 ]; then
   rm $TIMEFILE
   zenity --error --text "$PGMNAME is disabled. You can only play between $TIME1:00 and $TIME2:00"
   exit 0
fi

# check timespent
if [ $ELAPSED -ge $TIMELIMIT ]; then
    zenity --error --text "$PGMNAME is disabled. You have reached the limit of $TIMELIMIT minutes per day"
    exit 0
fi

#run game program. Mahjongg, at least, will come into the foreground automatically (its a GUI)
zenity --info --text "You have played $ELAPSED minutes today (of $TIMELIMIT). Press OK to continue" --timeout 15
`$PGMPATH` &

#main loop to track time
playon=true
while  $playon ; do
   #sleeping for a whole number of minutes makes it less likely to induce rounding errors
   #when I try to convert & round from seconds to minutes.
   sleep 60

   #check if Mahjongg is still being played
      #RESULT=`ps -ef | grep $PGMPATH | grep -v grep`
      #if [ -z $RESULT ]; then  #this has problems because of multiple output lines
      #or possibly strings with spaces in them

   RESULT=`ps -ef | grep $PGMPATH | grep -v grep | wc -w`
   if [ $RESULT -eq 0 ]; then
      updateTime
      zenity --info --text "Thank you for playing $PGMNAME. You have played $ELAPSED minutes so far today." --timeout 10
      exit 0
   fi

   updateTime

   #check for total time played so far
   if [ $ELAPSED -ge $TIMELIMIT ]; then
       $(sleep 1 && wmctrl -a Warning -b add,above)&
       $(zenity --warning --text "You have reached the limit of $TIMELIMIT minutes per day. Your game will end in 2 minutes" --timeout 30)
       playon=false
   fi

   #check for playing past the deadline
   HOUR=$(date +%H)
   if [ "$HOUR" -ge $TIME2 ]; then
       rm $TIMEFILE
       $(sleep 1 && wmctrl -a Warning -b add,above)&
       $(zenity --warning --text "You have reached the ending time of $TIME2:00 . You played $ELAPSED minutes today. Your game will end in 2 minutes" --timeout 30)
      playon=false
   fi
done

sleep 120
killall $PGMNAME
#---- THE END ----#