Linux View User Login record

Information about user logins is recorded in files such as utmp (/VAR/RUN/UTMP), wtmp (/var/log/wtmp), btmp (/var/log/btmp), and Lastlog (/var/log/lastlog).

The WHO, W, and users commands use the utmp (/var/run/utmp) file to query the current logged-on user's information.
The last and AC commands use the wtmp (/var/log/wtmp) file to query the information of the user who is currently logged in to the system.
The LASTB command queries the btmp (/var/log/btmp) file for information about all users who have failed to log on to the system.
The Lastlog command queries the user for the last logon information through the Lastlog (/var/log/lastlog) file.

Who command: Displays information about the user who is currently logged on

who Huey     pts/1        2015-05-11 18:29 (192.168.1.105) sugar    pts/2        2015-05-11 18:29 (192.168.1.105 )

W command: Displays the logged on user and the currently executing task

W 18:30:51 up 3 min,  2 users,  load average:0.10, 0.14, 0.06USER     TTY      from              [email protected]   IDLE   Jcpu   PCPU whathuey     pts/1    192.168.1.105    18:29    3.00s  0.52s  0.00s wsugar    pts/ 2    192.168.1.105    18:29    1:07   0.47s  0.47s-bash

The users command: Displays the user name of the user who is currently logged on

UsersHuey Sugar

Last command: Displays information about the user who is currently logged on to the system

last root     pts/3        192.168.1.105    Mon may 18:33-18:33  (00:00)    sugar    pts/2        192.168.1.105    Mon May one 18:32   still logged in   sugar    pts/2        192.168.1.105    Mon May 11 18:29- 18:32  (00:02)    Huey     pts/1        192.168.1.105    Mon may one 18:29 still   logged in   reboot   system boot  3.5.0-43-generic Mon may 18:27-18:33  (00:05)    Huey     PTS/1        192.168.1.105    Sat may  9 10:57-17:31  (06:33)

LASTB command: Displays information for all users who have failed to log on to the system

sudo lastbbtmp begins Sat may  9 09:48:59 2015

Lastlog command: Displays information about the last time a user logged in

lastlog User name           port     from             last login time root             pts/3    192.168.1.105  May 11 18:36:43 +0800 2015daemon * * Never logged in **bin * * never logged in **sys * * never logged in **......hplip * * never logged in                                      **saned                                      * * never logged in **huey             pts/1    192.168.1.105  May 18:29:40 +0800 2015guest-miznkv                               * * never logged in **guest-bcf1si                               * * Never logged in **sugar            pts/2    192.168.1.105  May 18:32:28 +0800 2015mysql                                      * * never logged in **sshd                                       * * Never logged in * *

AC command: Displays statistics of user connection time
A) Displays the total connection time for each day

ac-d May  9total        6.55Todaytotal        0.54

b) Show the total connection time for each user

ac-pHuey                                 6.78sugar                                0.23root                                 0.12total        7.13

Linux View User Login record