SUNWdoc
whatis looks up a given command and displays the header line from the manual section. You can then run the man(1) command to get more information. If the line starts ‘name(section) ...’ you can do ‘man -s section name’ to get the documentation for it. Try ‘whatis ed’ and then you should do ‘man -s 1 ed’ to get the manual page for ed(1) .
whatis is actually just the -f option to the man(1) command.
whatis uses the /usr/share/man/windex database. This database is created by catman(1M) . If this database does not exist, whatis will fail.