lastlog is huge

[Paul Howarth]

Hacksaw wrote:
>>lastlog is a *sparse* file that only records the last login of each user
>>at a fixed offset in the file (indexed by uid). If you have a user with a
>>large uid, the file will appear huge, but ls -s will show the true size.
>>
>>Log rotation will not help at all.
> 
> 
> True enough.
> 
> I must say that I find this to be of dubious utility. I suppose it's faster, 
> but how many people look at lastlog so often that it needs to be as fast as 
> possible? Even in the good old days when Linux was a baby penguin and real men 
> wrote code on Hazeltine terminals, one called lastlog at most a few times in a 
> day, mostly to see if friends had been on.
> 
> Surely a hash file makes more sense?

The way sparse files work means that it *is* effectively a hashed 
database, with all the clever stuff done at filesystem level. This is 
how *nix systems have done this sort of thing for aeons...

Paul.