Users and groups (Српски)

User groups are used on GNU/Linux for access control – members of a group are granted access to devices and files belonging to that group. Template:Filename is the file that defines the groups on the system (Template:Codeline for details).

This article provides a list of common groups and their purpose along with an overview of group manipulation commands.

Useful groups

Users often add their non-root user to the following groups to allow access to peripherals and other hardware.

• audio - for access to sound hardware
• floppy - za pristup flopiju ukoliko postoji
• lp - za pristup stampacu
• optical - for access to optical devices such as CD and DVD drives (e.g. playing audio CDs)
• power - used with power options (e.g. shutdown with power button)
• storage - for managing storage devices
• video - za video poslove i 3d akceleraciju
• wheel - za upotrebu sudo privilegija

Group list

A list of groups and their function (sorted alphabetically)

Group	Affected files	Purpose
adm	/var/log/*	Read access to log files in /var/log
audio	/dev/sound/*, /dev/snd/*, /dev/misc/rtc0	Access to sound hardware.
avahi
bin	/usr/bin/*	Right to modify binaries only by root, but right to read or executed by anyone. (Please modify this for better understanding...)
camera		Access to Digital Cameras.
clamav	/var/lib/clamav/*, /var/log/clamav/*
daemon
dbus	/var/run/dbus
disk	/dev/sda[1-9], /dev/sdb[1-9], /dev/hda[1-9], etc	Access to block devices not affected by other groups such as optical,floppy,storage.
floppy	/dev/fd[0-9]	Access to floppy drives.
ftp	/srv/ftp
games	/var/games	Access to some game software.
gdm
hal	/var/run/hald, /var/cache/hald
http
kmem	/dev/port, /dev/mem, /dev/kmem
locate	/usr/bin/locate, /var/lib/locate, /var/lib/slocate, /var/lib/mlocate	Right to use updatedb command.
log	/var/log/*	Access to log files in /var/log,
lp	/etc/cups, /var/log/cups, /var/cache/cups, /var/spool/cups	Access to printer hardware
mem
mail	/usr/bin/mail
network		Right to change network settings such as when using a Networkmanager.
nobody		Unprivileged group.
ntp
optical	/dev/sr[0-9], /dev/sg[0-9]	Access to optical devices such as CD,CD-R,DVD,DVD-R.
policykit
power		Right to use suspend utils.
rfkill
root	/* -- ALL FILES!	Complete system administration and control (root, admin)
scanner	/var/lock/sane	Access to scanner hardware.
smmsp		sendmail group
storage		Access to removable drives such as USB harddrives,flash/jump drives,mp3 players.
stb-admin
sys		Right to admin printers in CUPS.
thinkpad	/dev/misc/nvram	Right for thinkpad users using tools such as tpb.
tty	/dev/tty, /dev/vcc, /dev/vc, /dev/ptmx
users		Standard users group.
uucp	/dev/ttyS[0-9] /dev/tts/[0-9]	Serial & USB devices such as modems,handhelds,RS232/serial ports.
vboxusers	/dev/vboxdrv	Right to use Virtualbox software.
video	/dev/fb/0, /dev/misc/agpgart	Access to video capture devices, DRI/3D hardware acceleration.
vmware		Right to use VMware software.
wheel		Right to use sudo (setup with visudo), Also affected by PAM

Group manipulation

List groups

Display group membership with the Template:Codeline command:

$ groups [user]

If Template:Codeline is omitted, the current user's group names are displayed.

The Template:Codeline command provides additional detail, such as the user's UID and associated GIDs:

$ id [user]

To list all groups on the system:

$ cat /etc/group

Find group ownership

List files owned by a group with the Template:Codeline command:

# find / -group [group]

Manage group membership

Add users to a group with the Template:Codeline command:

# gpasswd -a [user] [group]

To remove users from a group:

# gpasswd -d [user] [group]

If the user is currently logged in, he/she must log out and in again for the change to have effect.

Manage groups

Create new groups with the Template:Codeline command:

# groupadd [group]

To delete existing groups:

# groupdel [group]