Re: [patch] who and stale utmp entries

[Paul Eggert]

Tim Waugh <address@hidden> writes:

> Here is a patch to prevent the who(1) command showing stale utmp
> entries of user logins.

That patch has a problem when process-IDs are reused.

Can you please explain more what is going on here?  As I understand
it, "users" and "pinky" do not suffer from the stale-utmp problem.
They do not invoke kill(), so they must have a method that doesn't
involve testing whether a process-ID exists.  Can we modify "who" to
use their method?

Also, does that patch attempt to send signals even when "who" is
invoked as (say) "who -q file"?  That doesn't sound quite right.