1. How can you create a user without useradd command
Follow the below link
How to create a user without useradd command?
2. What is the default permission on user's home directory?
3. What is the difference between .bash_profile and .bashrc?
Every time you login to a Linux (Red Hat) machine .bash_profile file is executed but In case you are already logged in and you open a new terminal then .bashrc file is executed
4. What is the command to create a user with a pre defined uid, shell and home directory?
useradd -m -d /path/to/home -s /bin/bash -u 550 <USER>
5. Explain each field of /etc/passwd
- 1st field: username
- 2nd field: x tells that an encrypted password is stored in /etc/shadow
- 3rd field: uid
- 4th field: gid
- 5th field: Description
- 6th field: home directory
- 7th field: default login shell
6. How to change primary group for any user?
usermod -g <groupname> <username>
7. If I delete a user, does it's home directory gets deleted? If not then what is the command to delete the home directory of user along with the user
# userdel -r <username>
8. Name any 3 files which are automatically created inside any user's home directory when a user is added
.bashrc .bash_profile .bash_history
9. What is the command to view all the currently logged in users?
10. What is the command to change and view the expiry date for any user?
11. What are the details you get with finger command?
Login Details Mail Home directory Last login
12. How can you give a normal user all the root level privileges?
Add the user to wheel group and uncomment the wheel group line in sudoers file
Give the user all command permission in sudoers
How to give normal user root privileges using sudo in Linux/Unix
13. Name any 3 groups of which root is a member by default
root bin daemon sys adm disk wheel
14. How can you give sudo access to any user without asking him to provide passord every time he runs a command?
Add an extra parameter NOPASSWD in sudoers file while giving the user permission to run root level commands
15. Why do we use visudo rather than editing the file with vi or any other editor?
Follow this link
A guide on visudo and its usage