User account and process management in Linux

The process is a program in execution. The process is created when a command is to be executed so, it can be called a running instance of a program in execution. Tuning or controlling a process is called Process Management. There are two types of Linux processes, normal and real-time. Real-time processes have a higher priority than all of the other processes. If there is a real-time process ready to run, it will always run first. Real-time processes may have two types of policy, round-robin and first in first out

A user account is a technique for connecting a user and information service or computer network.  A user account is comprised of a username, password and any information related to the user.

Locking a users’ password:
– You can check the status of a user’s account with passwd –S username. To lock the password, use the command passwd –l username

You can also use grep username /etc/shadow to check the status of a user accounts password.

The presence of the exclamation mark (!) as shown above means the password is locked. To unlock the password, use usermod –U username

Expire an account.
– The above methods for locking a password or a user account will still allow a user to access his account by SSH authentication or other PAM modules even if the account is locked. To completely disable a user’s account, use the chage command.

chage –E0 username
– This will prevent every access to the account

Setting an account expiration date
– You can use the chage command to set an account to expire at a particular date. The format will be chage –E “year-mm-dd” username. The date within the quotation mark represents the expiry date.

you can now check the new account settings by using chage –l username

Kill a users session:
– You use can use the kill command to ‘kill’ a particular process after identifying the process i.d. As always, when running such a command, you have to be absolutely certain that is the process you want. To effectively kill a user’s session, you will need the tty and pid component. To do this, you can use the who command or just w

After getting the tty, use it to get the matching pid component with the command ps –ft tty as shown below

Now, you can kill the session using the pid. The command to use;

kill PID

For example;

kill 2757

or you can forcefully kill the process by using kill -9 2757 

I hope you found this blog post helpful. If you have any questions, please let me know in the comment session.