man -K does the job but it's painfully slow to the point that googling is much faster, if Internet connection is available.
Is there a way to have the manpages indexed so that I can do full-text searches against them fast?
The old school way is to use glimpse, but there are many other document indexing / site search systems available these days, any one of them would work. You can also write your own based on FTS5 in SQLite if you're so inclined. Just format man pages as plain text and index them.
A Google search uses an index to find the relevant information whereas man pages are not indexed on a Unix system.
Furthermore, all systems will only keep compressed man pages by default which implies that man page search has to decompress every single man page on your system.
aproposis fast enough to not to go for internet. Can you post some output oftime apropos keywordand your expected fast time ?apropossearches only the heads of manpages, though. It should be the equivalent ofman -k.man -Ksearches whole manpages, but there's no index with the default setup. I was wondering if there's was an easy to use ready-made solution to speed it up.mandb. mandb - create or update the manual page index caches