linux login / logout log

last command:

-F, --fulltimes
    Print full login and logout times and dates.
-n, --limit number
    Tell last how many lines to show.
-f, --file file
    Tell last to use a specific file instead of /var/log/wtmp.  
    The --file option can be given multiple times, and all of the specified files will be processed.

last practice:

last | head -n 50
or
last -f -F wtmp

References:
Last turtorial for Beginner:
https://www.howtoforge.com/linux-last-command/
Last Result descriptiion:
https://unix.stackexchange.com/questions/36287/meanings-of-the-columns- in-last-command