How to add a user to a group in linux
show group
# groups [user]
group create
# groupadd [group]
add user to group
# gpasswd -a [user] [group]
show users
$ cat /etc/passwd|sed -e 's/:.*//g'
reset groups
$ newgrp wireshark
# groups [user]
# groupadd [group]
# gpasswd -a [user] [group]
$ cat /etc/passwd|sed -e 's/:.*//g'
$ newgrp wireshark