Intro To 'users' Command In Linux

2023-05-24 - By Robert Elder

I use the 'users' command to list all of the users that are currently logged into the system:

users

Here, you can see that I'm the only user who's logged in:

robert

Multiple Users Logged In

If I log into this computer a second time with the postgres user, I'll see this user as well:

sudo -u postgres -i

users

postgres robert

The 'users' command can show one user multiple times if they're logged in more than once using multiple methods such as through SSH or through terminal emulators:

users

robert robert

Specify A Different 'utmp' File

By default, the users command will read information from the file at '/var/run/utmp':

users /var/run/utmp

robert robert

This file contains information about currently logged in users but you can also specify the file at '/var/log/wtmp':

xxd /var/log/wtmp | head -n 10

00000000: 0100 0000 3500 0000 7e00 0000 0000 0000  ....5...~.......
00000010: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000020: 0000 0000 0000 0000 7e7e 0000 7275 6e6c  ........~~..runl
00000030: 6576 656c 0000 0000 0000 0000 0000 0000  evel............
00000040: 0000 0000 0000 0000 0000 0000 352e 3135  ............5.15
00000050: 2e30 2d35 332d 6765 6e65 7269 6300 0000  .0-53-generic...
00000060: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000070: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000080: 0000 0000 0000 0000 0000 0000 0000 0000  ................
00000090: 0000 0000 0000 0000 0000 0000 0000 0000  ................

which contains more information about previously logged in users, so it produces many more results:

users /var/log/wtmp

postgres postgres postgres postgres postgres postgres postgres postgres postgres postgres robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert robert

And that's why the 'users' command is my favourite Linux command.

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