Shell Programming and Scripting

#!/bin/sh

#Below command will print the login user name
oper=`whoami`



#Below command will print , on which user the script a.sh is running.
User=`ps -ef|grep a.sh|grep -v grep|awk '{print $1}'`

echo "Login User " $oper
echo "User Name  " $User

flag=0

listOfUsers=${echo $User | tr " " "\n"}
echo "List of Users " $listOfUsers

for userName in $listOfUsers
do
    echo $userName  
    if [ "${userName}" = "${oper}" ]
    then
    echo "Inside if aaaaaaa"
        flag=1
        exit 1
    fi
done


echo "flag value  " $flag 

if [ $flag -eq 1 ]
 then
 echo "Inside if bbbbbbbbb"
        echo "script is in progress..."
	
        exit 1
 else
        echo "Script is not running it initiated now."
	sleep 40
 fi

listOfUsers=$(echo $User | tr " " "\n")

touch $(whoami).lockfile ## to create a lock file for that particular user
rm $(whoami).lockfile ## add this in last line of a.sh

if [ -f $(whoami).lockfile ]
then
   echo "Lock file exists for $(whoami). Script is running ..." ; exit
else
   echo "Lock file not exists for $(whoami). Initiating new script .."
   sh a.sh
fi