How to jump to a particular flag in a Unix manpage?

What I do is put a few blank spaces in front of the flag like so:

/     -o

That's not 100% reliable but you jump through a much less hoops. If you want even better success rate, try "/^ +-o". That would find lines starting with blanks and followed by -o. I wouldn't like to type that weird string often though.

I have defined this function in my .bashrc

function manswitch () { man $1 | less -p "^ +$2"; }

which you can use as follows

manswitch grep -r

I got it from this commandlinefu.

Note: the argument to the -p switch of less is a regexp telling less to look for a line starting with (^) one or more spaces (+) followed by the switch (second arg. so $2), so it has the advantage of working with different formatting.

Also you can open the man page on specific position from command line with

man -P 'less -p "     -o"' mount

@piccobello's answer is great, but it was eating the colors in my man pages. Instead of piping to less (since man already uses less by default usually), I simply pass the modified less command to man:

function manswitch() { man -P "less -p \"^ +$2\"" $1 }

This retains the functionality @piccobello had in his function, but retains colors.