다중 사용자

# id

[root@localhost ~]# id
uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

누가 컴퓨터를 사용중인가?
#who 
[root@localhost ~]# who
root     :0           2017-02-10 21:18 (:0)
root     pts/0        2017-02-10 21:19 (:0)
root     pts/1        2017-02-11 00:01 (:0)
root     pts/2        2017-02-11 00:59 (:0)
centos   pts/3        2017-02-11 01:00 (::ffff:192.168.126.1)
[root@localhost ~]#