Linux Command - group commands

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Commands to create, delete, and modify groups.

A group is a logical collection of users on a system.

/etc/group

execute cat /etc/group to see all groups

sample output

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root:x:0:root
bin:x:1:root,bin,daemon
daemon:x:2:root,bin,daemon
sys:x:3:root,bin,adm
adm:x:4:root,adm,daemon
tty:x:5:
disk:x:6:root,adm
lp:x:7:lp
mem:x:8:
kmem:x:9:
wheel:x:10:root
floppy:x:11:root
mail:x:12:mail
news:x:13:news
uucp:x:14:uucp
man:x:15:man
cron:x:16:cron
console:x:17:
audio:x:18:
cdrom:x:19:
dialout:x:20:root
ftp:x:21:
sshd:x:22:
input:x:23:
at:x:25:at
tape:x:26:root
video:x:27:root
netdev:x:28:
readproc:x:30:
squid:x:31:squid
xfs:x:33:xfs
kvm:x:34:kvm
games:x:35:
shadow:x:42:
postgres:x:70:
cdrw:x:80:
usb:x:85:
vpopmail:x:89:
users:x:100:games
ntp:x:123:
nofiles:x:200:
smmsp:x:209:smmsp
locate:x:245:
abuild:x:300:
utmp:x:406:
ping:x:999:
nogroup:x:65533:
nobody:x:65534:

/etc/group file format

  1. Group name
  2. group password here, usually x. The group password is encrypted and stored in file /etc/gshadow.
  3. GID(Group ID) number
  4. usernames of the group members

groupadd

option description
-g, –gid GID set GID

add new group ‘dev’

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groupadd dev

To add user jimmy to a group

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usermod -aG dev jimmy

groupdel

Removing the group

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groupdel dev

groupmod

chagne group’s GID to be 3333

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groupmod -g 3333 dev

Reference