How can I check who is logged on my Linux system?

Linux is an extraordinary operating system, which lets the user record every single process running on it. Today, we are going to show some thrilling commands, using which you can track “who is logged on my Linux system”. This tutorial will be very useful for administrators and novice users to Linux.

w command example

who is logged on my Linux system.

1. command “w”

w displays information about the users currently on the machine, and
their processes.

ubuntu@ip-172-31-12-106:~$ w
 17:50:41 up 16 days,  1:09,  4 users,  load average: 0.00, 0.01, 0.05
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
ubuntu   pts/0    124.253.84.169   17:39    1.00s  0.04s  0.00s w
ubuntu   pts/1    124.253.84.169   17:48   58.00s  0.03s  0.01s sshd: ubuntu [priv]
vikas    pts/2    124.253.84.169   17:50   39.00s  0.04s  0.04s -bash
linuxtog pts/3    124.253.84.169   17:50    5.00s  0.04s  0.04s -bash

The header shows, in this order, the current time, how long the system has been running, how many users are currently logged on, and the system load averages for the past 1, 5, and 15 minutes.

• User – Displays the name of the user currently logged in the system.
• TTY – The Terminal number of a user.
• FROM – The IP Address of user.
• LOGIN@ – Login Time of a user.
• IDLE – The Free time after the execution of the last command performed by a user.
• JCPU – The JCPU time is the time used by all processes attached to the tty.
• PCPU – The PCPU time is the time used by the current process, named in the “what” field.
• WHAT – Current process executed by a user.

Examples of “w” command with various options.

• -h, –no-header (Don’t print the header.)

ubuntu@ip-172-31-12-106:~$ w -h
ubuntu   pts/0    124.253.84.169   17:39    8:33   0.04s  0.00s man w
ubuntu   pts/1    124.253.84.169   17:59    1.00s  0.03s  0.00s w -h
vikas    pts/2    124.253.84.169   17:59   12:57   0.03s  0.03s -bash
linuxtog pts/3    124.253.84.169   17:59   12:36   0.04s  0.04s -bash

• -s, –short (Use the short format. Don’t print the login time, JCPU or PCPU times.)

ubuntu@ip-172-31-12-106:~$ w -s
 18:14:12 up 16 days,  1:32,  4 users,  load average: 0.10, 0.09, 0.06
USER     TTY      FROM              IDLE WHAT
ubuntu   pts/0    124.253.84.169   10:12  man w
ubuntu   pts/1    124.253.84.169    3.00s w -s
vikas    pts/2    124.253.84.169   14:36  -bash
linuxtog pts/3    124.253.84.169   14:15  -bash

2. command “last”

The command “last” displays a list of all users logged in and logged out of the system with their username, IP Address used for login, Date and Time, and also specifies the duration of session by a particcular user. All these details are stored in the file /var/log/wtmp and “last” searches back through the file /var/log/wtmp.

ubuntu@ip-172-31-12-106:~$ last
linuxtog pts/3        124.253.84.169   Thu Sep 21 17:59   still logged in
vikas    pts/2        124.253.84.169   Thu Sep 21 17:59   still logged in
ubuntu   pts/1        124.253.84.169   Thu Sep 21 17:59   still logged in
linuxtog pts/3        124.253.84.169   Thu Sep 21 17:50 - 17:54  (00:03)
vikas    pts/2        124.253.84.169   Thu Sep 21 17:50 - 17:54  (00:04)
reboot   system boot  3.13.0-113-gener Tue Sep  5 16:41 - 18:47 (16+02:06)
ubuntu   pts/0        27.255.166.137   Mon Sep  4 04:04 - 05:06  (01:02)

wtmp begins Mon Sep  4 04:04:11 2017

3. command “last reboot”

The command “last reboot” will show a log of all reboots. It also fetches the data from the file /var/log/wtmp.

ubuntu@ip-172-31-12-106:~$ last reboot
reboot   system boot  2.6.32-642.15.1. Wed Sep  6 17:56 - 18:53 (15+00:57)
reboot   system boot  2.6.32-642.15.1. Tue Aug 22 17:52 - 16:49 (13+22:56)
reboot   system boot  2.6.32-642.15.1. Fri Mar 31 13:27 - 17:07 (144+03:40)
reboot   system boot  2.6.32-642.15.1. Fri Mar 31 13:17 - 13:26  (00:09)
reboot   system boot  2.6.32-642.15.1. Fri Mar 31 13:13 - 13:16  (00:03)
reboot   system boot  2.6.32-573.18.1. Fri Mar 31 12:59 - 13:12  (00:13)

wtmp begins Fri Mar 31 12:59:28 2017

We are coming to an end. Using above command we can track “who is logged on my Linux system”. We hope this tutorial will be helpful for all the viewers. Stay tuned for upcoming posts. Gooday!