Mailing List Archive: Fixing $PATH programmatically for non-interactive SSH

Fixing $PATH programmatically for non-interactive SSH

Mar 26, 2010, 8:01 AM

Post #1 of 3 (3580 views)

Hi there,

I'm looking for a way to fix programmatically the $PATH after an
incoming SSH connection, not only for remote interactive shells, but
for remote command execution also.

I'm using Debian Lenny with , and currently I have :

user@host:~$ ssh -V
OpenSSH_5.1p1 Debian-5, OpenSSL 0.9.8g 19 Oct 2007
user@host:~$ ssh localhost
[...]
user@host:~$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/games:/myowndir
user@host:~$ exit
user@host:~$ ssh localhost 'echo $PATH'
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

I would like to add /myowndir to the $PATH for remote command
execution, as well as for remote login shells.

As far I've investigated, $PATH is fixed by /etc/profile for interactive
connection. But unfortunately, for remote command execution, this script
is not executed.

I would like to add this dir to $PATH for all users except the famous
one with uid 0. So, I guess I can't use those basics key/value files
such as /etc/environment or ~/.ssh/environment.

Is there any simple way to deal with such constraints in OpenSSH?
Intuitively, I was thinking of well-thought combination of 'UsePAM yes'
and modules in /etc/pam.d/sshd?

Thanks in advance for any kind of help,
--
RÃ©mi PALANCHER IJD/SMI
Systems and networks administrator on Grid'5000
INRIA Saclay Building H
tel: +33 1 74 85 42 45 Office 015

Re: Fixing $PATH programmatically for non-interactive SSH [ In reply to ]

wooledg at eeg

Mar 26, 2010, 9:18 AM

Post #2 of 3 (3480 views)

Permalink

On Fri, Mar 26, 2010 at 04:01:53PM +0100, Rémi PALANCHER wrote:
> I'm using Debian Lenny with , and currently I have :

> I would like to add /myowndir to the $PATH for remote command
> execution, as well as for remote login shells.

One way is to put the PATH=... command in ~/.ssh/environment and then
make sure PermitUserEnvironment is set to yes in the sshd_config.

> As far I've investigated, $PATH is fixed by /etc/profile for interactive
> connection. But unfortunately, for remote command execution, this script
> is not executed.

That's correct.

> I would like to add this dir to $PATH for all users except the famous
> one with uid 0. So, I guess I can't use those basics key/value files
> such as /etc/environment

That's a Debianism, or at least a Linuxism. It's a configuration file
that's read by PAM (when readenv=1 appears in the matching PAM config file
entry). You -could- use that, in theory, but it's not a shell script.
So you can't do things like PATH=$PATH:/myowndir but rather, you have
to type out the entire PATH=/foo:/bar:/myowndir value. It's pretty bad.

(I once wanted to use it to set MAIL=$HOME/Maildir/ globally, but you
simply can't do that with it. I gave up. It's nigh useless.)

> or ~/.ssh/environment.

This is the appropriate place, as far as I can tell.

> Is there any simple way to deal with such constraints in OpenSSH?
> Intuitively, I was thinking of well-thought combination of 'UsePAM yes'
> and modules in /etc/pam.d/sshd?

Debian's sshd_config has "UsePAM yes" by default. So, if you do decide
to go with the /etc/environment thing, it ought to work, as far as I know.

Re: Fixing $PATH programmatically for non-interactive SSH [ In reply to ]

brad at bradcan

Mar 26, 2010, 9:22 AM

Post #3 of 3 (3477 views)

Permalink

Hi

you wrote:
>
>I'm looking for a way to fix programmatically the $PATH after an
>....

This might be what you're looking for:

SSH The Secure Shell, The Definitive Guide.
8.2.6 Setting Environment Variables - page 308