mpsh$ setenv TERM=vt100

Or with a back-quote for a private variable for one command:

mpsh$ xterm `DISPLAY=gamma:0.0

Expand with a dollar sign:

mpsh$ echo $TERM

Displayed in human-friendly format with the -s (show) option:

mpsh$ setenv -s

And in computer-readable format with the -q (show quoted) option:

mpsh$ setenv -q

And deleted with the -d option:

mpsh$ setenv -d name

Clear all with the -c option:

mpsh$ setenv -c