Create a new user account in CentOS Linux 7/8

The procedure is as follows for creating a new user account on CentOS Linux:

1. Use useradd command to add a new user account on a CentOS 7 or 8.
2. Run passwd command to set up or change user password.
3. Delete user account by typing the userdel command in CentOS.
4. To modify user account use usermod command.
5. To view user account information use id command.

Important files

Above commands modify the following files to create or delete user accounts:

Do not modify the following files using a text editor such as vim or nano to avoid misconfiguration.

• /etc/passwd – The password file contains one line for each user account.
• /etc/shadow – Password in encrpted format for the system’s accounts and optional aging (password expiration date) information.
• /etc/group – User group information.

Let us see all commands and examples in details.

Display a list of all Linux user account

The /etc/passwd file contains one line for each user account, with seven fields delimited by colons. Type cat command to list users:
cat /etc/passwd

uid=1000(vivek) gid=1000(vivek) groups=1000(vivek),4(adm),24(cdrom),27(sudo)

Finally, use the ls command to see the owner and group of a file named /etc/hosts:
ls -l /path/to/file
ls -l /home/vivek/Documents/resume.pdf
ls -l /etc/hosts
Run the ps command/top command to see owner of process:
ps
top
htop
top -u vivek
ps -au

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
gdm       1732  0.0  0.0 163872  6516 tty1     Ssl+ 12:34   0:00 /usr/lib/gdm3/gdm-x-session gnome-session --autostart /usr/share/gdm/greeter/autostart
root      1734  0.0  0.2 253836 86628 tty1     Sl+  12:34   0:03 /usr/lib/xorg/Xorg vt1 -displayfd 3 -auth /run/user/126/gdm/Xauthority -background none -noreset -keeptty -verbose 3
gdm       1825  0.0  0.0 263512 14224 tty1     Sl+  12:34   0:00 /usr/lib/gnome-session/gnome-session-binary --systemd --autostart /usr/share/gdm/greeter/autostart
vivek     2128  0.0  0.0 163872  6468 tty2     Ssl+ 12:35   0:00 /usr/lib/gdm3/gdm-x-session --run-script env GNOME_SHELL_SESSION_MODE=ubuntu /usr/bin/gnome-session --systemd --session=ubuntu
root      2130  1.5  0.4 307212 138348 tty2    Sl+  12:35   8:38 /usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -keeptty -verbose 3
vivek     5052  0.0  0.0  19752 12936 pts/1    Ss+  12:39   0:06 /usr/bin/ssh -oForwardX11 no -oForwardAgent no -oPermitLocalCommand no -oClearAllForwardings yes -oProtocol 2 -oNoHostAuthenticationForLocalhost y
vivek    24020  0.0  0.0  11144  5732 pts/4    Ss   21:13   0:00 bash
vivek    24961  0.0  0.0  14648  6784 pts/4    S+   21:17   0:00 ssh aws-ls.laws-v-zone-a-www-001
vivek    24995  0.0  0.0  14672  6896 pts/5    S+   21:18   0:00 ssh vivek@do-de.public
vivek    25204  0.0  0.0  11012  5156 pts/2    Ss   21:20   0:00 bash
vivek    25210  0.0  0.1 414796 40568 pts/2    Sl+  21:20   0:00 gpass

See how to “Show All Running Processes in Linux using ps/htop commands” for more information.

Creating a new CentOS user account from the command line

The syntax is:
sudo useradd userName
sudo useradd [options] userName

Examples

Create the vivek user account, run:
sudo adduser vivek
Verify it:
id vivek
Or use the grep command as follows:
grep -w '^vivek' /etc/passwd
grep -w '^vivek' /etc/group
Finally, set or change the password for vivek user by typing the following passwd command:
sudo passwd vivek

A new user account was created. Next, verify it by log in using the ssh command:
ssh vivek@your-centos-8-server-ip

Deleting user account in CentOS Linux 7/8

The syntax is:
sudo userdel {userName}
sudo userdel -r {UserName}
The -r option remove home directory and mail spool of given user account. So make a backup if you need user data. Let us delete the vivek user along with all personal data:
sudo userdel -r vivek
Verify that the user vivek is successfully deleted from CentOS server:
id vivek
grep -w '^vivek' /etc/passwd
grep -w '^vivek' /etc/group

Advance examples

Let us create a new accout named www-files as follows:
$ sudo useradd -d /home/www-files -m \
-c "Nginx file and sftp user" \
-s /bin/bash www-files
$ sudo passwd www-files
$ id www-files
Where,

• -d /home/www-files : Home directory is /home/www-files of the new account
• -m : Create the user’s home directory
• -c "Nginx file and sftp user" : Set up GECOS field of the new account (comment)
• -s /bin/bash : Set login shell of the new account
• www-files : Login/Username

How to modify user accounts

You need to usermod as follows:
usermod [options] {username}
Please note that the user account must exists in order to use usermod. Let us see some common examples.

Set new value of the GECOS field (comment

sudo usermod -c "Vivek Gite" vivek
## verification ##
grep -w 'vivek' /etc/passwd

Update home directory location for the user account

Change /home/vivek to /home/ftpvivek, run:
sudo usermod -d /home/ftpvivek -m vivek

Lock the user account

sudo usermod -L vivek

Unlock the user account

sudo usermod -U vivek

Create a Sudo User on CentOS

All members of the wheel group have sudo access. So all you have to do is append user account to the wheel group as follows:
sudo usermod -aG wheel {username}
##
## add vivek user to wheel group for sudo access ##
##
sudo usermod -aG wheel vivek
id vivek
Next, login as vivek user and test sudo access:
{vivek@my-centos8-box:~ }$ sudo ls /root/
{vivek@my-centos8-box:~ }$ sudo -s
{root@my-centos8-box:~ }#
See “Linux Add User To Group” for more info.

Linux Change or Rename User Name and UID (user-id)

sudo usermod -l login-name old-name
# rename 'vivekg' user to 'vivek' #
sudo usermod -l vivek vivekg
See “How to Change a USER and GROUP ID on Linux For All Owned Files” for more info.

Getting help

Use man command or pass the --help as follows:

usermod command

Run:
man 8 usermod
usermod --help

passwd command

Execute:
man 8 passwd
passwd --help

useradd command

Type:
man 8 useradd
useradd --help

Conclusion

You learned how to create a new user account and modify or delete user them on CentOS Enterprise Linux 7 or 8. See CentOS/RHEL 8 docs here for more info.