About the 'who' command & it's Output on '14.04 TrustyTahr'

Solution 1:

Try upgrading the package that contains the who command; even if you did use a strange version of the ISO to install from, an update should replace it:

Find out what package owns who:

which who    # find out where 'who' binary is
dpkg -S /path/to/who

Then:

apt-get update
apt-get install <package name from dpkg -S command>

If it still doesn't work, try a different shell with no environment (to get rid of any wonky environment variables, setups, bash-specific junk, etc.):

env -i /bin/dash
$ who

If it works in a bare shell, then the problem is likely a weird alias definition in a bashrc, or something similar.

Also, does who --all work?