CentOS7 User Account Management

1. Configuration Files

1.1 User Configuration File

The format contains: username: password: user ID: group ID: comment: home directory: login shell The 'x' indicates the password is stored separately in /etc/shadow

1.2 Group Configuration File

1.3 Password Storage File

2. Creating Users

When creating a user without specifying a group, a group with the same name as the user is automatically created and assigned to the user Syntax: createuser [options] username Options: -c #comment, specify a descriptive comment -d #directory, specify the user's home directory, if it doesn't exist, use -m to create it -g #group, specify the primary group -G #group, specify additional groups -s #shell, specify the login shell -u #uid, specify the user ID, with -o option, can reuse other user IDs

3. Deleting Users

Syntax: removeuser [options] username Options: -r #remove the user's home directory

4. Modifying Users

Syntax: modifyuser [options] username Options: Common options are similar to 'createuser' Examples: 1. This command changes user john_doe's login shell to bash, home directory to /home/john, and primary group to dev_ops. 2. Replaces sarah's current supplementary groups with team1 and team2 Adds team4 as a supplementary group while keeping existing ones Changes the username

5. User Password Management

Setting user passwords is an important aspect of user management When a user account is first created, it has no password and is locked until a password is set, even if it's empty The root user can set passwords for themselves and others, while regular users can only modify their own password Syntax: setpass [options] username Options: -l #lock the password, disabling the account -u #unlock the password -d #remove password, disabling the account -f #force user to change password on next login If no username is specified, modifies the current user's password Examples: Reset password Set maximum password lifetime to 180 days Set account expiration date (note the format)