Create delete and modify local user accounts

Managing local user accounts on Linux is essential for security, privacy, and streamlined administration. Each user should have a dedicated account so they:

Keep personal files and directories protected by proper permissions
Configure their own environment and tool settings
Operate with the least privilege, reducing accidental damage and attack surface

The image shows a dark interface with the text "Manage Local User Accounts" on the left and a user icon in the center. The word "KodeKloud" is in the top right corner.

1. Creating a New User

Use useradd to provision a fresh account.

sudo useradd john

By default, this performs:

Action	Description
Create user and group	A new user named `john` and a primary group `john` with matching GID
Home directory	`/home/john` is created and populated from `/etc/skel`
Default shell	`/bin/bash`
Account expiration	No expiration date (unlimited)
Password	Unset (must be initialized with `passwd`)

Inspect `/etc/skel`

Skeleton files define initial user config.

ls -a /etc/skel
# .  ..  .bash_logout  .bash_profile  .bashrc

You can also review default parameters:

useradd --defaults
# GROUP=100
# HOME=/home
# INACTIVE=-1
# EXPIRE=
# SHELL=/bin/bash
# SKEL=/etc/skel
# CREATE_MAIL_SPOOLS=yes

2. Setting a Password

After account creation, assign a strong password:

sudo passwd john
# Changing password for user john.
# New password:

3. Deleting a User

Remove user accounts carefully:

Task	Command
Delete account (keep home directory)	`sudo userdel john`
Delete account + home + mail spool	`sudo userdel --remove john`<br>`sudo userdel -r john`

Data Loss Warning

Using --remove (or -r) will delete the user’s home directory and mail spool permanently.
Always back up important data before proceeding.

4. Customizing Account Creation

Pass flags to override defaults:

Option	Description	Example
`-d, --home <dir>`	Custom home directory	`sudo useradd -d /home/special_john john`
`-s, --shell <shell>`	Specify login shell	`sudo useradd -s /bin/zsh john`
`-u, --uid <UID>`	Assign specific user ID	`sudo useradd -u 1100 smith`
`-g, --gid <GID-or-name>`	Assign primary group (must exist or be created)	`sudo useradd -g 1100 smith`

5. Inspecting User Records

Account metadata resides in /etc/passwd:

cat /etc/passwd | grep john
# john:x:1001:1001::/home/john:/bin/bash

Field breakdown: username:password:UID:GID:comment:home:shell

View file ownership under /home:

ls -l /home/
# drwxr-xr-x 2 john john 4096 Feb  5 10:00 john

Display numeric IDs:

ls -ln /home/

6. Identifying the Current User

Command	Output
`id`	UID, GID, groups, and SELinux context (if applicable)
`whoami`	Current username

id
whoami
# aaron

7. System Accounts

System accounts serve daemons and services. They typically have UIDs below 1000 and no home directory:

sudo useradd --system sysacc

8. Modifying an Existing User

Use usermod to update user settings:

Change	Command
Move home directory	`sudo usermod -d /home/newdir -m john`
Rename user	`sudo usermod -l jane john`
Change login shell	`sudo usermod -s /bin/zsh jane`
Lock account	`sudo usermod --lock jane` `<br>` `sudo usermod -L jane`
Unlock account	`sudo usermod --unlock jane` `<br>` `sudo usermod -U jane`
Set expiration date (YYYY-MM-DD)	`sudo usermod -e 2022-01-01 jane`
Remove expiration date	`sudo usermod -e "" jane`

9. Password Aging with `chage`

Control password policies using chage:

Policy	Command
Force change on next login	`sudo chage -d 0 jane`
Reset last password change	`sudo chage -d -1 jane`
Set max days between changes	`sudo chage -M 30 jane`
Disable expiration	`sudo chage -M -1 jane`
View aging info	`sudo chage -l jane`

10. References

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