Linux Display Date And Time Of Login

How do I display user last login date and time under Linux operating systems?

Linux use the following two files to keep track of user login sessions:

a] /var/run/utmp - List of current login sessions.

b] /var/log/wtmp - List of previous login sessions.

c] /var/log/btmp - List all the bad login attempt.

last command

The last command searches back through the file /var/log/wtmp file and displays a list of all users logged in (and out) since that file was created. Names of users and tty's can be given, in which case last will show only those entries matching the arguments. Names of ttys can be abbreviated, thus last 0 is the same as last tty0. Type the following command:
last last username
Sample outputs:

vivek    pts/3        :0.0             Thu Oct 29 00:46   still logged in
vivek    pts/0        :0.0             Wed Oct 28 23:14   still logged in
vivek    pts/2        :0.0             Wed Oct 28 22:12 - 23:11  (00:58)
vivek    pts/0        :0.0             Wed Oct 28 21:43 - 23:11  (01:27)
vivek    tty7         :0               Wed Oct 28 21:41   still logged in

Task: Find Out Who Was Logged In At A Particular Time

To display the state of logins as of the specified time to determine easily who was logged in at a particular time specify that time with -t option and look for "still logged in".
last -t YYYYMMDDHHMMSS last -t 20091028231100 username

Task: Show Only Tty Matching Entries

Use the following syntax:
last tty last tty2 last pts/3

lastb command

The lastb command is the same as last command, except that by default it shows a log of all the bad login attempts, enter:
lastb lastb username lastb vivek lastb pts/2