w command is a basic Unix command that helps you to quickly confirm general system status and to see which users are logged (and what they're doing right now).
Basic w command Example
Just type w in command line prompt to see the basic output (I'm running this on my MacOS laptop):
[email protected]:~ $ w 10:37 up 1 day, 11:41, 4 users, load averages: 2.38 2.54 2.61 USER TTY FROM LOGIN@ IDLE WHAT greys console - Mon22 35:38 - greys s000 - Mon22 25 /usr/bin/less -is greys s001 - Mon22 - w greys s002 - 10:22 3 -bash
You will immediately recognise that some of this functionality is provided by the uptime command and who command, but in addition your w command shows you current command each user is running (last column).