These two scripts are very important for the system admin who regularly
works with mail servers and somehow forgets to backup his system
username and password! Let’s say somehow we lost the usernames and passwords of the mail server. In this case the admin has
to manually create all the users and then change the passwords for
all the users. Tedious job. Let’s make our life easier.

First create a file which contains all the user name. Something like
this:

nurealam

nayeem

mrahman

farid

rubi

sankar

Save the file as userlist.txt. Now
create the following bash file:

#!/bin/sh

for i in `more userlist.txt `

do

echo $i

adduser $i

done

Save the file and exit.

chmod 755 userlist.txt

Now run the file:

./userlist.txt

This will add all the users to the system. Now we have to change the
passwords. Let's say we want username123 as password. So for user nayeem
the password will be nayeem123, rubi123 for user rubi and so on.

Create another bash file as follows:

#!/bin/sh

for i in `more userlist.txt `

do

echo $i

echo $i"123" | passwd –-stdin "$i"

echo; echo "User $username’s password changed!"

done

Run the file. All the passwords are changed.