There are three types of Linux user accounts: administrative, service, and regular accounts. User accounts are identified by a UID and stored in configuration files like /etc/passwd and /etc/shadow. Commands like useradd, passwd, and usermod allow administrators to add, modify, and delete user accounts and configure account properties.

1. User Adminstration

2. Overview
● Purpose of user administration
● Types of user accounts
● Adding , Modifying and deleting user accounts.
● User related configuration files
● Giving command permission to users through sudo.
● Recovery of User related configuration files.

3. ● There are three basic types of Linux user accounts:
- Administrative account (root)
- Service account - games, ftp, etc...
- Regular account
● Each user account is identified by UID (0 - 60,000)
- administrative (root) - 0
- service accounts – 1 - 499
- Regular accounts – 500 - 60,000
Types of user accounts

4. Configuration files
1. /etc/passwd
username:x:UID:GID:Full Name:Home_Directory:Shell
2. /etc/shadow
3. /etc/group
4. /etc/gshadow

5. 1. # id -To get uid and gid of a user
2. # useradd [newusername]
3. # passwd [username]
4. # useradd -u [uid] [newusername]
5. # usermod -u [uid] [username]
6. # usermod -g [gid] [username]
7. # su

6. 8. # usermod -s [shell location] [username]
9. # usermod -l [newname] [oldname]
10. # usermod -L [username]
11. # usermod -U [username]
12. # passwd -l [username]
13. # passwd -u [username]
14. # usermod -e [yy-mm-dd] [username]
15. # chage -l [username]