#print
The editor and the 'shell' (the normal command
interpreter) accept different commands.  The
shell (which types '$' at you) understands
"ls", "mv", "cp", "date" and so forth; the
editor understands such commands as 'w' or 'q'.

Who knows about "diff"?
Type "answer shell" or "answer editor".
#copyin
#user
#uncopyin
#match shell
#log
#next
4.2b 5
4.1b 10