From: George Ogata <george.ogata@...>
Date: 2007-01-30T19:22:48+09:00
Subject: Re: How to get the unix login name of the calling user?

On 1/30/07, Moritz Reiter <mo@agrav.org> wrote:
> Hi,
>
> I am writing a script which uses a configuration file. I already managed
> that it is possible for the caller to specify the location of the config
> file as a command line parameter (which was pretty easy with optparse).
> Now I want to set the default location of for the config file to
> /home/username/.my_config_file. Therefore I have to get the username of
> the user who is calling the script.
>
> My idea would be to parse /etc/passwd for the return value of
> Process.uid but as I am pretty unexperienced in ruby I wanted to ask
> here if someone could tell me a more elegant method to do it?

* If you just need the user's home directory, use
File.expand_path('~/.my_config_file').

* If you actually need the user's login name, the USER envvar is
usually (always?) set to this -- so ENV['USER'].

* If you really need to traipse through passwd ruby also comes with an
'etc' file parsing library.

  require 'etc'

Then:

  user = Etc.getpwuid(Process.uid).name

Or:

  effective_user = Etc.getpwuid(Process.euid).name

More info:

  http://ruby-doc.org/stdlib/
  (Although I've just noticed that clicking on 'etc' gives a 500...)