This article will explain and share how to add and remove user account with useradd(add) and userdel (remove) from the command-line on linux RHEL 6/7, CentOS 6/7, Oracle Linux 6/7 server.
1. Adding a New User to an Linux System.
a) Get the useradd manual :
# man useradd
useradd - create a new user or update default new user information
b) To creates the new account and the /home/john home directory :
# useradd --home /home/ehowstuff ehowstuff
c) useraddd command does not set any valid password by default, and user cannot log in until a password is set.To set the password user the following command :
# passwd ehowstuff Changing password for user ehowstuff. New password: Retype new password: passwd: all authentication tokens updated successfully.
d) Verify the values in /etc/password :
# cat /etc/passwd | grep ehowstuff ehowstuff:x:501:501::/home/ehowstuff:/bin/bash
e) Verify the values in /etc/group :
# cat /etc/group | grep ehowstuff ehowstuff:x:501:
f) Verify email user created for id ehowstuff :
# ls /var/spool/mail | grep ehowstuff ehowstuff
More useradd options :
-c, –comment COMMENT
Add a value, such as a full name, to the GECOS field.
-g, –gid GROUP
Specify the primary group for the user account.
-G, –groups GROUPS
Specify a list if supplementary groups for the user account.
Used with the -G option to append the user to the supplemental groups mentioned without removing the user from other groups.
-d, –home HOME_DIR
Specify a new home directory to a new location. Must be used with the -d option.
Move a user home directory to a new location. Must be used with the -d option.
-s, –shell SHELL
Specify a new login shell for the user account.
Lock a user account.
Unlock a user account.
2. Deleting a User from an Linux System.
a) Get userdel manual :
# man userdel
userdel - delete a user account and related files
b) userdel username removes the user from /etc/passwd, but leaves the home directory intact by default. Proper command to remove the user’s account, user’s home directory and mail spool as part of the deletion process :
# userdel --remove ehowstuff
# userdel -r ehowstuff
When a user is removed with userdel without the -r option specified, the system will have files that are owned by an unassigned user ID number. This can also happen when files created by a deleted user exist outside their home directory. This situation can lead to information leakage and other security issues.