Re: [dev] [PATCH] Check for presence of SHELL environment variable

From: Eric Pruitt <eric.pruitt_AT_gmail.com>
Date: Wed, 29 Oct 2014 18:58:48 -0700

On Wed, Oct 29, 2014 at 09:52:14PM +0100, k0ga_AT_shike2.com wrote:
> I read this sentence as 'SHELL variable must hold always the value of
> the user preferred command in the /etc/passwd file, and any program
> that create a session must be aware of setting it from /etc/passwd'.
> The sentence doesn't say that the user's preferred command language
> interpreter is the value of SHELL instead of the value of /etc/passwd.
>
> > such, st should check for its presence when deciding what shell to
> > use; just as HOME can be defined to override one's passwd-defined home
> > directory, a user should also be able to override their passwd-defined
> > shell using the SHELL environment variable.
>
> HOME must hold the value of the user's home directory, if this
> value is not the value of /etc/passwd then you have an error
> in your configuration. The same can be said about SHELL. You
> can change your shell selection using chsh.

I don't agree with your interpretation of the POSIX verbiage, but
regardless, in my experience, the vast majority of applications check
for $HOME before checking a user's passwd entry and the same applies
with shells. Going with the principal of least surprise, this patch
makes perfect sense. Even if you ignore that. I think SHELL could be a
considered a special case -- a user may not have control of their system
shell, and their only option for overriding it is updating SHELL after
logging in.

Eric
Received on Thu Oct 30 2014 - 02:58:48 CET