Re: binary search in a file

[Sorav Bansal]

> > Is there a utility to search for a value in a sorted file using binary 
> > search. The file was sorted using the 'sort' command.
[/snip]

> Is there any reason why you want to use a binary search, except for speed?

Well, linear search on a 60GB file is likely to be many orders of 
magnitude slower than binary search.

> Unless the lines are fixed-length, after each chop, the search program
> will have to find the start-of-line character.
> This is likely to negate any advantage gained from binary searches.

Just a little bit. Finding the start-of-line is easy and quite fast 
since it is an in-memory operation. The speed in such operations is 
usually limited by disk-I/Os


> I'd sugest just sticking to grep. You can use the '-l' (ell) option -
> this will exit when the first matching line is found, (but not display 
>  it).

I ended up writing my own binary search utility. We are discussing if it 
should be made a part of gnu.coreutils.

Sorav