Buptime is not avaliable for csh.
Buptime counts bashish uptime. It was written by ratdog in the early days of bashish. Call these code snippets to use it in a theme:
$(buptime h) bashish's hours
$(buptime m) bashish's minutes
$(buptime s) bashish's seconds
$(buptime sd) system's days
$(buptime sh) system's hours
$(buptime sm) system's minutes
$(buptime users) system's users
$(buptime load1) system's load
$(buptime load2) ""
$(buptime load3) ""