List Linux Groups and Users

List Linux Groups and Users

II. Linux Groups

A Linux group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the file server. When you add a user to a group, that user inherits all of the privileges of the group.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the user john belongs to, you would use the following command:

$ groups john

This command would output a list of all of the groups that the user john belongs to.

You can also use the usermod command to add or remove users from groups. To add a user to a group, you would use the following command:

$ usermod -aG  

To remove a user from a group, you would use the following command:

$ usermod -d  

For more information on managing groups, please see the Linux.com tutorial on managing groups.

II. Linux Groups

A Linux group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the /etc/shadow file. When you create a new user account, you can specify which groups that user belongs to.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the current user belongs to, you would use the following command:

$ groups

The output of this command will list all of the groups that the current user belongs to, along with the group ID (GID) for each group.

You can also use the getent group command to list all of the groups on the system. For example, to list all of the groups on the system, you would use the following command:

$ getent group

The output of this command will list all of the groups on the system, along with the group name, GID, and members of each group.

User Groups

A user group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the file server. When you add a user to a group, that user inherits all of the privileges of the group.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the user john belongs to, you would use the following command:

$ groups john

This command would output a list of all of the groups that the user john belongs to, such as:

john  adm cdrom sudo dip plugdev video

The first column of the output shows the name of the group, and the second column shows the privileges that the group has.

You can also use the getent group command to list all of the groups on the system. For example, to list all of the groups on the system, you would use the following command:

$ getent group

This command would output a list of all of the groups on the system, such as:

adm:x:4:root,daemon
cdrom:x:24:cdrom
dip:x:3:root
sudo:x:27:root
video:x:44:video

The first column of the output shows the name of the group, the second column shows the group ID, and the third column shows the list of users who belong to the group.

Listing Groups

To list all of the groups on your system, you can use the groups command. This command will display a list of all of the groups that the current user belongs to. For example, if you run the following command, you will see a list of all of the groups that the user username belongs to:

$ groups username

The output of this command will look something like this:

username  adm cdrom sudo dip plugdev video

This output shows that the user username belongs to the following groups:

  • adm: This group is for system administrators.
  • cdrom: This group is for users who can access CDs.
  • sudo: This group is for users who can run sudo commands.
  • dip: This group is for users who can use the dhcpcd command.
  • plugdev: This group is for users who can access USB devices.
  • video: This group is for users who can access video devices.

5. User Groups

A user group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the company's payroll system. When you add a user to a group, that user inherits all of the privileges that are associated with the group.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the user john belongs to, you would use the following command:

groups john

The output of this command will look something like this:

john adm cdrom sudo dip floppy audio video plugdev netdev

This means that the user john belongs to the following groups:

  • adm: This group has the ability to administer the system.
  • cdrom: This group has the ability to access CD-ROM drives.
  • sudo: This group has the ability to run commands as root.
  • dip: This group has the ability to install and remove packages.
  • floppy: This group has the ability to access floppy drives.
  • audio: This group has the ability to access audio devices.
  • video: This group has the ability to access video devices.
  • plugdev: This group has the ability to access USB devices.
  • netdev: This group has the ability to access network devices.

You can also use the getent group command to list all of the groups on the system. For example, to list all of the groups on the system, you would use the following command:

getent group

The output of this command will look something like this:

```
# /etc/group
root:x:0:0
daemon:x:1:1
bin:x:2:2
sys:x:3:3
adm:x:4:4
tty:x:5:5
disk:x:6:6
lp:x:7:7
mail:x:8:8
news:x:9:9
uucp:x:10:10
man:x:11:11
proxy:x:12:12
kmem:x:15:15
dialout:x:20:20
fax:x:21:21
voice:x:22:22
cdrom:x:24:24
floppy:x:25:25
tape:x:26:26
sudo:x:27:27
audio:x:29:29
video:x:30:30
plugdev:x:46:46
netdev:x:47:47
```

VI. Viewing Groups

To view the groups that a user belongs to, you can use the groups command. For example, to view the groups that the user john belongs to, you would use the following command:

groups john

This command will output a list of all of the groups that the user john belongs to.

You can also use the groups command to view the groups that you belong to. To do this, simply omit the username from the command. For example, the following command would output a list of all of the groups that you belong to:

groups

VII. Managing Groups

You can manage groups using the following commands:

  • adduser to add a user to a group
  • deluser to remove a user from a group
  • usermod to change a user's group membership
  • groupadd to create a new group
  • groupdel to delete a group
  • groupmod to change a group's name or other attributes

For more information on managing groups, see the Linux groups documentation.

Deleting Groups

To delete a group, use the groupdel command. The syntax is as follows: groupdel group-name For example, to delete the users group, you would use the following command: groupdel users

You will be prompted to confirm the deletion. If you type y, the group will be deleted.

Note that deleting a group does not delete the users who belong to that group. To remove a user from a group, use the usermod command.

Adding Users to Groups

To add a user to a group, use the following command:

usermod -aG groupname username

For example, to add the user "john" to the group "wheel", you would use the following command:

usermod -aG wheel john

You can also use the following command to add a user to multiple groups at once:

usermod -aG group1, group2, group3 username

Once you have added a user to a group, they will automatically have the permissions of that group.

For more information on adding users to groups, please see the Linux user groups tutorial.

Removing Users from Groups

To remove a user from a group, you can use the following command:

``` usermod -G ```

Where:

  • usermod is the usermod command
  • -G is the option to specify the group
  • group is the name of the group
  • username is the name of the user

For example, to remove the user john from the group sudo, you would use the following command:

``` usermod -G sudo john ```

Once you have run this command, the user john will no longer be a member of the group sudo.

II. Linux Groups

A Linux group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the file server. When you add a user to a group, that user inherits all of the privileges of the group.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the user john belongs to, you would use the following command:

$ groups john

This command would output a list of all of the groups that the user john belongs to.

You can also use the usermod command to add or remove users from groups. To add a user to a group, you would use the following command:

$ usermod -aG  

To remove a user from a group, you would use the following command:

$ usermod -d  

For more information on managing groups, please see the Linux.com tutorial on managing groups.

II. Linux Groups

A Linux group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the /etc/shadow file. When you create a new user account, you can specify which groups that user belongs to.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the current user belongs to, you would use the following command:

$ groups

The output of this command will list all of the groups that the current user belongs to, along with the group ID (GID) for each group.

You can also use the getent group command to list all of the groups on the system. For example, to list all of the groups on the system, you would use the following command:

$ getent group

The output of this command will list all of the groups on the system, along with the group name, GID, and members of each group.

User Groups

A user group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the file server. When you add a user to a group, that user inherits all of the privileges of the group.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the user john belongs to, you would use the following command:

$ groups john

This command would output a list of all of the groups that the user john belongs to, such as:

john  adm cdrom sudo dip plugdev video

The first column of the output shows the name of the group, and the second column shows the privileges that the group has.

You can also use the getent group command to list all of the groups on the system. For example, to list all of the groups on the system, you would use the following command:

$ getent group

This command would output a list of all of the groups on the system, such as:

adm:x:4:root,daemon
cdrom:x:24:cdrom
dip:x:3:root
sudo:x:27:root
video:x:44:video

The first column of the output shows the name of the group, the second column shows the group ID, and the third column shows the list of users who belong to the group.

Listing Groups

To list all of the groups on your system, you can use the groups command. This command will display a list of all of the groups that the current user belongs to. For example, if you run the following command, you will see a list of all of the groups that the user username belongs to:

$ groups username

The output of this command will look something like this:

username  adm cdrom sudo dip plugdev video

This output shows that the user username belongs to the following groups:

  • adm: This group is for system administrators.
  • cdrom: This group is for users who can access CDs.
  • sudo: This group is for users who can run sudo commands.
  • dip: This group is for users who can use the dhcpcd command.
  • plugdev: This group is for users who can access USB devices.
  • video: This group is for users who can access video devices.

5. User Groups

A user group is a collection of users who share common privileges. For example, you might create a group for all of the users who are allowed to access the company’s payroll system. When you add a user to a group, that user inherits all of the privileges that are associated with the group.

You can use the groups command to list all of the groups that a user belongs to. For example, to list all of the groups that the user john belongs to, you would use the following command:

groups john

The output of this command will look something like this:

john adm cdrom sudo dip floppy audio video plugdev netdev

This means that the user john belongs to the following groups:

  • adm: This group has the ability to administer the system.
  • cdrom: This group has the ability to access CD-ROM drives.
  • sudo: This group has the ability to run commands as root.
  • dip: This group has the ability to install and remove packages.
  • floppy: This group has the ability to access floppy drives.
  • audio: This group has the ability to access audio devices.
  • video: This group has the ability to access video devices.
  • plugdev: This group has the ability to access USB devices.
  • netdev: This group has the ability to access network devices.

You can also use the getent group command to list all of the groups on the system. For example, to list all of the groups on the system, you would use the following command:

getent group

The output of this command will look something like this:

```
# /etc/group
root:x:0:0
daemon:x:1:1
bin:x:2:2
sys:x:3:3
adm:x:4:4
tty:x:5:5
disk:x:6:6
lp:x:7:7
mail:x:8:8
news:x:9:9
uucp:x:10:10
man:x:11:11
proxy:x:12:12
kmem:x:15:15
dialout:x:20:20
fax:x:21:21
voice:x:22:22
cdrom:x:24:24
floppy:x:25:25
tape:x:26:26
sudo:x:27:27
audio:x:29:29
video:x:30:30
plugdev:x:46:46
netdev:x:47:47
```

VI. Viewing Groups

To view the groups that a user belongs to, you can use the groups command. For example, to view the groups that the user john belongs to, you would use the following command:

groups john

This command will output a list of all of the groups that the user john belongs to.

You can also use the groups command to view the groups that you belong to. To do this, simply omit the username from the command. For example, the following command would output a list of all of the groups that you belong to:

groups

VII. Managing Groups

You can manage groups using the following commands:

  • adduser to add a user to a group
  • deluser to remove a user from a group
  • usermod to change a user’s group membership
  • groupadd to create a new group
  • groupdel to delete a group
  • groupmod to change a group’s name or other attributes

For more information on managing groups, see the Linux groups documentation.

Deleting Groups

To delete a group, use the groupdel command. The syntax is as follows:

groupdel group-name

For example, to delete the users group, you would use the following command:

groupdel users

You will be prompted to confirm the deletion. If you type y, the group will be deleted.

Note that deleting a group does not delete the users who belong to that group. To remove a user from a group, use the usermod command.

Adding Users to Groups

To add a user to a group, use the following command:

usermod -aG groupname username

For example, to add the user “john” to the group “wheel”, you would use the following command:

usermod -aG wheel john

You can also use the following command to add a user to multiple groups at once:

usermod -aG group1, group2, group3 username

Once you have added a user to a group, they will automatically have the permissions of that group.

For more information on adding users to groups, please see the Linux user groups tutorial.

Removing Users from Groups

To remove a user from a group, you can use the following command:

“`
usermod -G
“`

Where:

  • usermod is the usermod command
  • -G is the option to specify the group
  • group is the name of the group
  • username is the name of the user

For example, to remove the user john from the group sudo, you would use the following command:

“`
usermod -G sudo john
“`

Once you have run this command, the user john will no longer be a member of the group sudo.

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