Topics Summary

 

Here, we talk about some of the miscellaneous commands that can be used to check different account login information.

 

Whoami Command

This command is used to know, the logged in credential details.

Sample command output:

[root@sys2 ~]# whoami
root

 

Drawback: We can’t know other users details with this.

 

id Command

id command will display userid, primary and secondary id details of the given user.

 

Syntax:

id user-name

 

Example-1:

[root@sys2 ~]# id john

uid=501(john) gid=502(dba) groups=502(dba),501(sales)

 

Note:

In the above example, we have seen a non-root user account information from other non-root user.

 

Example-2:

If we give no user name details after the id command, then it will display the logged on user name information.

[root@sys2 ~]# id
uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

 

In the above example, as we have logged in as root, it showed the root id details.

 

last command

Linux last command will explain about server reboots along with different user’s login details history.

Example-1:

[admin@linbox1 log]$ last
admin           pts/0                 :0                           Sun     Jul  24    10:29    still logged in
admin           :0                      :0                           Sun     Jul  24    10:29    still logged in
(unknown     :0                      :0                           Sun     Jul  24    10:18 - 10:29 (00:11)
reboot          system boot      3.10.0-327.el7.x    Sun     Jul  24    10:18 -  17:47 (07:29)
admin           pts/0                 :0                           Thu     Jun 16   05:47 -  05:48 (00:01)
admin           :0                      :0                           Thu     Jun 16   05:47 -  05:48 (00:01)
(unknown    :0                       :0                           Thu     Jun 16   05:46 -  05:47 (00:00)
reboot          system boot      3.10.0-327.el7.x     Thu    Jun 16   05:46 -  17:47 (38+12:00)
root              pts/0                  192.168.1.30          Thu     Jun 2    12:17 -  down (06:29)
(unknown    :0                       :0                             Thu    Jun 2     12:16 -  18:47 (06:30)
reboot          system boot      3.10.0-327.el7.x      Thu    Jun 2     12:16 -  18:47 (06:30)

 

Example-2:

Using last command, we can see a particular user login & logout details history over the period.

#last<username> The user’s login and logout users.

[admin@linbox1 log]$ last admin
admin      pts/0     :0   Sun   Jul  24  10:29   still logged in
admin      :0          :0   Sun   Jul  24  10:29   still logged in
admin      pts/0     :0   Thu   Jun 16  05:47 - 05:48 (00:01)
admin      :0          :0   Thu   Jun 16  05:47 - 05:48 (00:01)

wtmp begins Thu Jun 2 10:33:13 2016

 

Finger Command

Finger command is used for display user login credentials.
#finger <username> To display the user login details.

 

[root@sys2 ~]# finger john
Login: john                          Name: systemadmin
Directory: /home/john         Shell: /bin/bash
On since Tue Jan 26 18:25 (IST) on pts/3 from 192.168.1.4 11 seconds idle

 

Uptime Command

This command will show below details.

Number of users presently logged in.

For how many hours/days system is up.

cpu load average

 

Example:

[admin@linbox1 log]$ uptime
17:58:22 up 5:34, 2 users, load average: 0.00, 0.03, 0.05

 

Who Command

Who command will list out,

User names which are currently logged in

From which terminal they have logged in.

Date & timestamp of their login.

IP address details, if login was from remote machine.

 

Syntax example:

[root@linbox1 log]# who
admin       :0           2016-07-24            10:29 (:0)
admin        pts/0     2016-07-24            10:29 (:0)
admin        pts/1     2016-07-24            18:01 (:0)

 

w command

w command will show combinations of uptime output and who command information.

Check out the below example output,

[root@linbox1 log]# w
18:04:21 up 5:40, 3 users, load average: 0.02, 0.06, 0.05

 

USER   TTY   FROM   LOGIN  @ IDLE  JCPU  PCPU  WHAT
admin     :0         :0        10:29       ?xdm?     6:28    0.42s    gdm-session-worker

                                                                                             [pam/gdm-password]
admin    pts/0     :0        10:29        5.00s      0.29s  10.50s   /usr/libexec/gnome-

                                                                                              terminal-server
admin    pts/1     :0        18:01        2:53        0.07s   0.07s     bash

 

[root@sys2 Packages]# users

root root root root
#lastlog List all last logged in users
#cat /var/log/secure The users login and logout details

 

If FILE is not specified, use /var/run/utmp. /var/log/wtmp as FILE is common.