Creating Users and Groups in Linux

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Creating a User

1. Via GUI Tools
   • Some distros have a GUI tool you can use
   • Find from the Menu
2. Via Shell
   • every distro supports useradd utility
   • e.g., sudo useradd -m -c "Hoburn Washburne" -u 1006 hwash
     • -m sets a home directory
     • -c adds a comment field containing full name
     • -u sets UID of 1006
     • sets username to hwash
   • when an account is created, it is in a locked state
     • user cannot login
     • to unlock, need to use passwd command

Modifying an Account

Check If a User is Logged In

• some account changes could be disruptive if a user is logged in
  • check if the user is logged out:
    • who
    • w
    • last shows a list of recent logins and who is still logged in
      • displays data stored in /var/log/wtmp

1. Using GUI tools
   • usually can modify:
     • Account type
       • standard or privileged user
     • Name
     • Password
     • Groups
2. Using Shell
   • passwd changes a user’s password
     • e.g., sudo passwd hwash
       • enter new password
       • retype
       • done
     • can also adjust password aging and other options
   • usermod modifies an existing user
     • options are identical to useradd
     • e.g., sudo usermod -u 1072 -m -d /home2/hwash hwash
       • -u changes UID to 1072
       • -m changes home directory to /home2/hwash
       • -d moves contents of original home to the new home

Deleting Accounts

1. Delete via GUI
2. Delete via Shell
   • userdel command deletes accounts from CLI
     • e.g., sudo userdel hwash
     • -r option deletes user’s home directory
       • does not delete user’s home directory by default
     • -f option force deletes a user if they are currently logged in
       • will still complain about user being used by a process, but will still delete the account

Managing Groups

1. Using GUI Tools
   • can typically find in Menu
   • typically part of User management
2. Via Shell
   • groupadd command creates a group
     • e.g., groupadd -g 1001 consultants
   • to add users to group:
     • usermod -aG consultants rich
   • groups rich checks all groups for an account
   • groupmod command modifies a group
   • groupdel deletes a group

Wheel Group

The wheel group is an important group used for system administration.

• members are granted admin privileges
  • allows access to sudo command
• not all distros use this group