Question

If I run this on OS X:

last -10 | awk '{print $1}'

I get:
chop
chop
chop
chrihopk
reboot
shutdown
chop
chop
chop
chrihopk

How do I use sed or awk to obtain the most frequent user ‘chop’?

ADDITIONAL EDIT TO QUESTION:
Our local admin account interferes with the results (username: support) and often we have a new starter on a client box.
How could I modify

last -1  

to omit the following and return the last valid username:

support
reboot
shutdown

Thanks

Answer 1

In answer to your edit, leave off the numeric argument to last and use egrep like this:

last | egrep -v 'support|reboot|shutdown'

then pipe that into awk as in the other answers.