Shell Programming and Scripting

#!/bin/ksh                            
TTY=$(tty)                            
if [ "a$TTY" = "anot a tty" ]         
then  
        CRON="YES"                                
        echo cron job                 
else                        
        CRON="NO"          
        echo terminal session at $TTY 
fi

if [ -t 0 ] ; then
   inputTERM=1
fi;

#!/bin/ksh                                                 
ps -ef |grep /etc/cron                                     
ps -ef |grep etc/cron|read user cronpid discard            
echo  /etc/cron is $cronpid                                
ps -ef |grep $cronpid |grep $0|read user startpid discard  
echo startpid is $startpid                                 
if [ "a$startpid" = "a" ]                                  
then                                                       
        echo is not a cron job                             
        exit 1                                             
fi                                                         
echo $0                                                    
pid=$$                                                     
echo  my process is $0 pid $pid                            
ps -ef |grep $0 |grep $startpid                            
ps -ef |grep $0 |grep $startpid|read user pid1 discard     
echo $pid $pid1 should be same                             
if [ $pid -eq $pid1 ]                                      
then                                                       
        echo is cron job                                   
else                                                       
        echo is not cron job                               
fi