This manual describes how to work with Linux users through the terminal (using the command line).
Creating users in linux
Syntax:
useradd <username> [options]Example:
useradd developerIn this example, the developer account is created.
For the account, you should immediately create a password:
passwd developer*after entering, the system will ask you to enter the password twice.
| Key | Description and examples |
|---|---|
| -b | The base directory for new login home directories useradd developer -b /var/home |
| -c | It is a short description(comment) of the login useradd developer -c “User for deploy soft” |
| -d | Specifies the home directory path for the new user useradd developer -d /home/newuser |
| -D | Allows you to show or change the default settings that will be applied the next time you create users useradd developer -Ds /bin/bash |
| -e | After this date, no user will be able to access this login useradd developer -e 2025-12-31 |
| -f | Number of days after which an account with an obsolete password will be locked out useradd developer -f 3 |
| -g | Specifies the main group useradd developer -g group |
| -G | Specifies additional groups useradd developer -G wheel |
| -k | Skeleton source path (new user template files) useradd developer -k /var/skel |
| -m | When creating a user, create a home directory useradd developer -m |
| -M | Do not create a home directory useradd developer -M |
| -N | Do not create a primary group with the same name as the user useradd developer -N |
| -o | Allows the creation of an account with a duplicate UID useradd developer -u 15 -o |
| -p | Sets a password useradd developer -p pass |
| -r | System account (no home directory and with IDs in the range SYS_UID_MIN – SYS_UID_MAX from the /etc/login.defs file) useradd developer –r |
| -R | Directory for chroot useradd developer -R /var/chroot/home |
| -s | Path to command line shell useradd developer -s /bin/csh |
| -u | Sets the UID useradd developer -u 666 |
| -U | The group name will be the same as the user useradd developer -U |
How to edit user
Syntax:
usermod <username> [options]Example:
usermod developer -G wheelthis command add user developer to wheel group
How to delete user
Syntax:
userdel <username> [options]Example:
userdel developer -G wheelHow to block user
You can block a user without removing him from the system:
usermod -L <username>Example:
usermod -L developerTo unblock a user, enter:
usermod -U <username>How to manage group in linux
Create group:
groupadd <group> [options]Edit group:
groupmod <group> [options]Removing a group:
groupdel <group> [options]Adding a user to a group:
Executed via the usermod command:
usermod -a -G <comma-separated groups> <user>Removing from a group:
Executed with gpasswd:
gpasswd --delete <user> <comma-separated groups>A list of users
You can view the list of users in the /etc/passwd file:
cat /etc/passwdWe will see something like:
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
...As a rule, most of the user data is system – their UID is less than 1000 and more than 60000.
A more functional command for displaying the contents of the passwd file is getent:
getent passwdYou can find a user by ID:
getent passwd 1000Get a list of non-system users:
getent passwd {1000..60000}Get only a list of logins of non-system accounts:
getent passwd {1000..60000} | awk -F: '{ print $1}'