I'm writing something where I need to get the user id (or username - either way I can eventually use the getpw* functions) of the user who actually logged in. The problem is that the script in question is run as root - but not setuid (for various reasons). So users login as themselves, then "su" to root.

The solution I was using was to just check $ENV{LOGNAME}. However it seems this isn't set to the logged in user when the user types "su -" instead of plain old "su".

I know this can be done, because /usr/bin/ftp does it (when you ftp to some site, it still gives you the option of using the username you logged in as for the remote username). Does ftp just traverse up the process tree until it finds a process not owned by root, or ultimately finds init?

Any help to solve this greatly appreciated.

In reply to How to get the logged in user id by Matts

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