Daily Commands: Linux mix commands

Add user in Kali Linux or other Linux:

First of all let’s confirm which version of Linux and Kernel I’m running.In command prompt type in
```
uname –a
lsb_release –a
```

Now let’s add user. Open terminal and type following to create new user (replace user1 with your desired user name)
```
useradd -m user1
```
(Note: -m means create home directory which is usually /home/username)

Now set password for this user
```
passwd user1
```
Enter desired password twice

Add user to sudo group (to allow user to install software, allow printing, use privileged mode etc.)
```
usermod -a -G sudo user1
```
(Note: -a means append or add and –G mean to specified group/groups)

Change default shell of previously created user to bash
```
chsh -s /bin/bash user1
```
(Note: chsh mean change login shell, -s is the name of the specified shell you want for the user, in this case /bin/bash)
Nice, all worked out as expected.
Let’s logout and login back as our new Standard Non-root user (user1)

Login as new user

Once logged in, let’s confirm from command line who I really am! In terminal type in the following
```
whoami
```
Take note of user1@kali prompt. That also confirms who you are.
And let’s check my group affinity, type in the following in terminal:
```
groups
```
Looks good to me so far.
I am part of user1 group (my primary) and sudo group. That means I can run privileged commands or just become root myself if required.
Become root!
```
sudo su –
```
and type in user1’s password to become root.

See the prompt becomes root@kali instead of user1@kali. That means you’re now root and get to run anything Kali got to offer.
Lets confirm that using whoami command
```
whoami
```
So far so good. Now how do you delete a user?

Delete user in Kali Linux:

Log in as root user again. Open terminal and type:
```
userdel –r user1
```
(Note: -r means delete all files and home directory for user1)
You can replace user1 with your desired user name.

I have an error “user1 is currently used by process 5866”.
So process ID 5866 is being used by user1. (I know that it’s the gnome-keyring process running in background when I used sudo su – command earlier. (Gnome-Keyring error is quite common in Debian when you install multiple Windows or Desktop Managers. There’s a separate guide see How to fix Gnome-Keyring error. This demonstrates how to fix gnome-keyring error for root user). In our case we are not worried as we just want to delete that user.
Let do that.
Type in the following in terminal to kill the process used by user1.
```
kill -9 5866
```
This kills the process immediately.

(Note: don’t kill root or system processes unless you know what you’re doing)
Now let’s try to delete the user again.
```
userdel –r user1
```
We have a message. “userdel: user1 mail spool (/var/mail/user1) not found”.
(Note: -r means delete all files and home directory for user1)
Are we going to worry about it? Not really, we never created a mailbox for user1.
Just to confirm everything for user1 was deleted list files in home directory
```
ls /home
```
Nothing.. that’s good news, all files and folders were deleted for user1.
Want to double-check?
```
su user1
```
Perfect user1 was deleted successfully.