Shell Programming and Scripting

 # CREATE N NO. OF USERS WITH PASSWORD IN SYSTEM



# ./users to run the script

# CREATE A FUNCTION CALLED ADD()

ADD ()

{

   while [ $i  -le $no ]

      do
          echo -e " Please enter the user name :\t\c"
          read USER

#  Search in /etc/passwd file for user existence

          output=`cat /etc/passwd | grep $USER | cut -d: -f1`


            if [ "$output" = "$USER" ]

            then

    echo " Opps ! $USER is already exist Please Enter again"


## Call ADD Function in case of User already exist

                  ADD
            fi

           useradd $USER

          echo -e " Please enter the Password of the user :\t\c"

          read PASSWD

          echo $PASSWD | passwd --stdin $USER

echo "$USER creates successfully"

          i=`expr $i + 1`


done

}


clear

echo -e " Please Enter How many users want to create :\t\c"

read no

i=1


# Call ADD Function

ADD

 Please Enter How many users want to create :    2
 Please enter the user name :    viv

 Opps ! viv is already exist Please Enter again

 Please enter the user name :    vishnu
 Opps ! vishnu is already exist Please Enter again

 Please enter the user name :    ram
useradd: user 'ram' already exists
 Please enter the Password of the user :    kev

Changing password for user ram.
passwd: all authentication tokens updated successfully.
ram creates successfully

 Please enter the user name :    john
 Please enter the Password of the user :    john
Changing password for user john.
passwd: all authentication tokens updated successfully.
john creates successfully

useradd: user 'john' already exists
 Please enter the Password of the user :    john
Changing password for user john.
passwd: all authentication tokens updated successfully.
john creates successfully

useradd: user 'john' already exists
 Please enter the Password of the user :    jhon
Changing password for user john.
passwd: all authentication tokens updated successfully.
john creates successfully
[root@Riyansh Scripts]#

...
    if [ "$output" = "$USER" ]
    then
      echo " Opps ! $USER is already exist Please Enter again"
      ## Call ADD Function in case of User already exist
      continue
    fi
...

output=`grep ^$USER /etc/passwd | cut -d: -f1`

output=`grep \^"${USER}:" /etc/passwd | cut -d: -f1`