Managing users in Linux

Here is the very useful list of commands used to manage users.

1. su (1) – run a shell with substitute user and group IDs
2. useradd (8) – Create a new user or update default new user information
3. userdel (8) – Delete a user account and their files from the system. The command “userdel -r newuser” will remove the user and deletes their home directory.
4. usermod (8) – Modify a user account.
5. adduser(8) – Command used to add user accounts.
6. chage (1) – Used to change the time the user’s password will expire.
7. chfn(1) – Change a user’s finger information
8. chsh(1) – Change a user’s shell.
9. chgrp (1) – Changes the group ownership of files.
10. chown (1) – Change the owner of file(s ) to another user.
11. gpasswd (1) – Used to administer the /etc/group file.
12. groupadd (8) – Create a new group.
13. grpconv (8) – Creates /etc/gshadow from the file /etc/group which converts to shadow passwords.
14. grpunconv (8)- Uses the files /etc/passwd and /etc/shadow to create /etc/passwd, then deletes /etc/shadow which converts from shadow passwords.
15. groupdel (8) – Delete a group
16. groupmod (8) – Modify a group
17. groups (1) – print the groups a user is in
18. grpck (8) – Verify the integrity of group files.
19. id(1) – Print group or user ID numbers for the specified user.
20. newgrp(1) – Allows a user to log in to a new group.
21. newusers (8) – Update and create new users in batch form.
22. nologin (5) – Prevent non-root users from logging onto the system.
23. passwd (1) – Used to update a user’s password. The command “passwd username” will set the password for the given user.
24. pwconv (8) – Used to create the file /etc/shadow from the file /etc/passwd to convert to shadow passwords.
25. pwunconv (8) – Uses the files /etc/passwd and /etc/shadow to create /etc/passwd, then deletes /etc/shadow to convert from shadow passwords.