[NTLUG:Discuss] $PATH=what??!

[Kevin Brannen]

Cameron,

Comments & explanations embedded...

Cameron wrote:
> 
> i've got a problem that's bugging the pooh out of me.  i'm trying to run
> a remote command with ssh that it NOT is the systems default $PATH.
> here's what i've found so far ("/snip" means i cut some stuff out):
> 
>   $ ssh bravo2 set
>   (/snip)
>   PATH=/usr/bin:/bin:/usr/local/bin
>   SHELL=/bin/bash

This executes on the remote machine, so that is what you really have
there.

> 
>   $ ssh bravo2 echo $PATH
>   /bin:/usr/bin:/usr/local/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/local/lam-6.3/bin

Please consider _WHO_ expands $PATH here.  If you said ``your shell on
the *local* machine'', take the gold star. :-)

> 
>   $ ssh bravo2 "set ; echo $PATH ; set"
>   (/snip)
>   PATH=/usr/bin:/bin:/usr/local/bin
>   (/snip)
>   /bin:/usr/bin:/usr/local/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/local/lam-6.3/bin
>   (/snip)
>   PATH=/usr/bin:/bin:/usr/local/bin

Same thing.  The $PATH is only in double quotes, so your local shell
expands it, then passes that to ssh, who obediently gives it back to
you.

> 
> you'll notice that `set` and `echo $PATH` yield different values no
> matter how you turn it.  the context in which i need to do this (using
> LAM/MPI) doesn't make the "export..." stuff very appealing.  and that
> last command really confuses the heck out of me.  anyway, to the heart
> of my problem:  where can i set the default, system-wide,
> shell-independent(?) $PATH?  i'm running Mandrake 6.1.  i've looked
> through /etc/rc.d/ but no luck.  btw, in /etc/profile the path gets set
> to "$PATH:/usr/X11R6/bin", so i know it's not effecting anything.
> 
> well, bash gurus...it's time to step forward.  i'm at my wits end.  any
> help would be greatly appreciated.  TIA

No guru'ness needed, just experience. :-)  Do "man bash" and read the
part on quoting very carefully; especially the part that starts:

Enclosing characters in double quotes preserves  the  lit­
eral  value  of all characters within the quotes, with the
exception of ...

And I'll leave you hanging so you'll read that paragraph and at least
the 4 above it. :-)  Or, just look over the entire section labeled
"QUOTING".

HTH,
Kevin