sshd, plink, bash and path problems

sshd, plink, bash and path problems

[Tim Shadel]

I'm not subscribed to the list.  Kindly CC: me in any threads that 
result from this email.  Thanks.

Here's my setup:

Client:  Win2K box with Putty/Plink
Server: Win2K professional with cygwin/sshd (actually copssh, but it's 
just a minimal cygwin install)

I can login just fine.  I can use public key authentication fine.

Here's what I'd like to do:

plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 
mkdir -p /var/some/dir/that/does/not/exist

Nothing happens.  Here's something else I tried to see what's going on:

plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 
echo $PATH
/cygdrive/c/j2sdk...

Basically my entire Windows path prints out -- NOT my cygwin path.  I 
saw another post on this in a different context 
(http://www.cygwin.com/ml/cygwin/2003-07/msg01700.html), and I can see 
that it's a matter of commands getting executed when the login process 
happens.  So then I tried this:

plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 
source /etc/profile; echo $PATH
/bin:/cygdrive/c/WINNT/system32:/cygdrive/c/WINNT

And got the output I expected.  BUT, the plink command is being issued 
by a program that I can't modify (apache's maven deploy plugin), so I 
wondered two things:

1. What's different between plink <host> <command> and plink <host> 
(which displays a prompt) that causes the magical "login" process to 
occur.  Is this a plink thing? a bash thing? a cygwin-version-of-either 
thing?

2. Is there a file (.rc something-or-other perhaps?) that I can create 
that will make the "source /etc/profile" call once plink connects, so I 
can have the right path when <command> happens?

Any help with this would be most appreciated.

Thanks,

Tim Shadel

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Re: sshd, plink, bash and path problems

[Larry Hall]

At 09:56 PM 5/5/2004, you wrote:
>I'm not subscribed to the list.  Kindly CC: me in any threads that result from this email.  Thanks.
>
>Here's my setup:
>
>Client:  Win2K box with Putty/Plink
>Server: Win2K professional with cygwin/sshd (actually copssh, but it's just a minimal cygwin install)
>
>I can login just fine.  I can use public key authentication fine.
>
>Here's what I'd like to do:
>
>plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 mkdir -p /var/some/dir/that/does/not/exist
>
>Nothing happens.  Here's something else I tried to see what's going on:
>
>plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 echo $PATH
>/cygdrive/c/j2sdk...
>
>Basically my entire Windows path prints out -- NOT my cygwin path.  I saw another post on this in a different context (http://www.cygwin.com/ml/cygwin/2003-07/msg01700.html), and I can see that it's a matter of commands getting executed when the login process happens.  So then I tried this:
>
>plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 source /etc/profile; echo $PATH
>/bin:/cygdrive/c/WINNT/system32:/cygdrive/c/WINNT
>
>And got the output I expected.  BUT, the plink command is being issued by a program that I can't modify (apache's maven deploy plugin), so I wondered two things:
>
>1. What's different between plink <host> <command> and plink <host> (which displays a prompt) that causes the magical "login" process to occur.  Is this a plink thing? a bash thing? a cygwin-version-of-either thing?
>
>2. Is there a file (.rc something-or-other perhaps?) that I can create that will make the "source /etc/profile" call once plink connects, so I can have the right path when <command> happens?
>
>Any help with this would be most appreciated.


Sorry, I don't use putty or plink (and actually since they aren't part of 
the Cygwin distribution, much discussion of them is off-topic for this 
list).  But I expect your problem isn't putty/plink specific but rather
operator-error.  I can reproduce the same "problem" you're reporting with
'ssh' (which is part of the Cygwin distribution).  I believe you want:

plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 'echo $PATH'

Does that clarify what's going on for you?


--
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
838 Washington Street                   (508) 893-9889 - FAX
Holliston, MA 01746                     


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Re: sshd, plink, bash and path problems

[Tim Shadel]

I'm not subscribed to the list.  Kindly CC: me in any threads that result from this email.  Thanks.


Larry Hall wrote:

> Sorry, I don't use putty or plink (and actually since they aren't part 
> ofthe Cygwin distribution, much discussion of them is off-topic for 
> this list).

Understood.  I'll try rephrase my original question in terms of ssh.

> But I expect your problem isn't putty/plink specific but rather 
> operator-error. I can reproduce the same "problem" you're reporting 
> with 'ssh' (which is part of the Cygwin distribution). I believe you want:
>
>plink -batch -2 -i C:\path\to\my\key\mykey.PPK -l tims 159.87.127.66 'echo $PATH'
>  
>
Hmm.  I tried to replicate this with 'ssh' as well, after you mentioned 
it.  Here's what I did:

1.  Use Putty to connect to the cygwin machine via SSH.
2.  Use 'ssh-keygen' to create a key on the cygwin machine, and add it 
to the authorized_keys file.
3.  Use 'ssh-agent' and 'ssh-add' to hold my key in memory so it can be 
used without a prompt
4.  Use 'ssh localhost <command>' to simulate the 'plink' setup I 
described earlier

What I found is this:

(a) ssh localhost echo $PATH

returned the correct cygwin path, but

(b) ssh localhost 'echo $PATH'

returned the full Windows path, not the cygwin path, and

(c) ssh localhost "echo $PATH"

returned the correct cygwin path as well.  But as I think about it, I 
actually can't change the quotes used around the command (since it's 
issued by a program over which I have no control).  What I CAN 
manipulate is the cygwin environment contacted by the ssh/plink program.

>1. What's different between plink <host> <command> and plink <host> (which displays a prompt) that causes the magical "login" process to occur.  Is this a plink thing? a bash thing? a cygwin-version-of-either thing?
>  
>
Let me rephrase this a bit.  What happens differently between (a) and 
(b) above on the _server_ side?

>2. Is there a file (.rc something-or-other perhaps?) that I can create that will make the "source /etc/profile" call once plink connects, so I can have the right path when <command> happens?
>  
>
Can I change the cygwin environment (server side) to handle both (a) and 
(b) in the same way?  I'm familiar with Linux, but Cygwin (and 
especially its interaction with Windows: environment, permissions, etc) 
is brand new to me.

The quotation difference is step in the right direction (I know what to 
rule out), and I'm sure with a bit more info I'll be able solve my 
problem.  I appreciate your help.

Thanks,

Tim


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Re: sshd, plink, bash and path problems

[Igor Pechtchanski]

On Thu, 6 May 2004, Tim Shadel wrote:

> I'm not subscribed to the list.  Kindly CC: me in any threads that
> result from this email.  Thanks.
>
> [snip]
> What I found is this:
>
> (a) ssh localhost echo $PATH
>
> returned the correct cygwin path, but
>
> (b) ssh localhost 'echo $PATH'
>
> returned the full Windows path, not the cygwin path, and
>
> (c) ssh localhost "echo $PATH"
>
> returned the correct cygwin path as well.  But as I think about it, I
> actually can't change the quotes used around the command (since it's
> issued by a program over which I have no control).  What I CAN
> manipulate is the cygwin environment contacted by the ssh/plink program.
>
> >1. What's different between plink <host> <command> and plink <host>
> >(which displays a prompt) that causes the magical "login" process to
> >occur.  Is this a plink thing? a bash thing? a cygwin-version-of-either
> >thing?

It's a plink thing.  FWIW, ssh behaves similarly.

> Let me rephrase this a bit.  What happens differently between (a) and
> (b) above on the _server_ side?

Why not try it locally, like this:

echo echo $PATH
echo 'echo $PATH'
echo "echo $PATH"

and then

sh -xc 'PATH=/blah;echo $PATH'
sh -xc "PATH=/blah;echo $PATH"

> >2. Is there a file (.rc something-or-other perhaps?) that I can create
> >that will make the "source /etc/profile" call once plink connects, so I
> >can have the right path when <command> happens?

Well, you can tell ssh to invoke a login shell (e.g., "ssh a@b bash -l -c
'commands'").  I don't know about plink.

> Can I change the cygwin environment (server side) to handle both (a) and
> (b) in the same way?

No.  If you run the above experiments, you'll see why.

> I'm familiar with Linux, but Cygwin (and especially its interaction with
> Windows: environment, permissions, etc) is brand new to me.

This has nothing to do with Cygwin.  This is pure shell stuff.

> The quotation difference is step in the right direction (I know what to
> rule out), and I'm sure with a bit more info I'll be able solve my
> problem.  I appreciate your help.
>
> Thanks,
> Tim

HTH,
	Igor
-- 
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      |\      _,,,---,,_		pechtcha@cs.nyu.edu
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     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski, Ph.D.
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Re: sshd, plink, bash and path problems

[Tim Shadel]

Igor Pechtchanski wrote:

>Why not try it locally, like this:
>
>echo echo $PATH
>echo 'echo $PATH'
>echo "echo $PATH"
>
>and then
>
>sh -xc 'PATH=/blah;echo $PATH'
>sh -xc "PATH=/blah;echo $PATH"
>

Aah.  I forgot about the meanings of various quotes in bash.  That's an 
excellent example.

>>>2. Is there a file (.rc something-or-other perhaps?) that I can create
>>>that will make the "source /etc/profile" call once plink connects, so I
>>>can have the right path when <command> happens?
>>>      
>>>
>
>Well, you can tell ssh to invoke a login shell (e.g., "ssh a@b bash -l -c
>'commands'").  I don't know about plink.
>

plink also allows commands to be run.  That "bash -l -c 'commands'" 
works great.  I see if there's any way to change the code to use it, but 
that solves my problem.

>>Can I change the cygwin environment (server side) to handle both (a) and
>>(b) in the same way?
>>    
>>
>
>No.  If you run the above experiments, you'll see why.
>

Yup.  Thanks.

>This has nothing to do with Cygwin.  This is pure shell stuff.
>  
>

I guess I didn't know the original PATH was the windows one.  That makes 
more sense now.  So I'd see the same thing on a Linux box using pure 
ssh.  If the PATH were changed by /etc/profile, and I didn't use the 
"bash -l -c 'commands'" stuff to force a bash login, then I wouldn't see 
the new PATH there either.

I assume that the only way to 'source /etc/profile' requires a change to 
the content after "ssh a@b".  For example, '"ssh a@b bash -l -c 
'commands'" and "ssh a@b source /etc/profile; commands" both work for 
me.  I only wish I could "ssh a@b commands" and have it work.  I've got 
the info I need to figure out a different solution, though.  Thanks!

>HTH,
>	Igor
>  
>

It helps immensely.  Thank you very much.

Tim

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Re: sshd, plink, bash and path problems

[Igor Pechtchanski]

On Thu, 6 May 2004, Tim Shadel wrote:

> Igor Pechtchanski wrote:
>
> [snip]
> >>>2. Is there a file (.rc something-or-other perhaps?) that I can create
> >>>that will make the "source /etc/profile" call once plink connects, so I
> >>>can have the right path when <command> happens?
> >
> >Well, you can tell ssh to invoke a login shell (e.g., "ssh a@b bash -l -c
> >'commands'").  I don't know about plink.
>
> plink also allows commands to be run.  That "bash -l -c 'commands'"
> works great.  I see if there's any way to change the code to use it, but
> that solves my problem.
>
> [snip]
> >This has nothing to do with Cygwin.  This is pure shell stuff.
>
> I guess I didn't know the original PATH was the windows one.  That makes
> more sense now.  So I'd see the same thing on a Linux box using pure
> ssh.  If the PATH were changed by /etc/profile, and I didn't use the
> "bash -l -c 'commands'" stuff to force a bash login, then I wouldn't see
> the new PATH there either.
>
> I assume that the only way to 'source /etc/profile' requires a change to
> the content after "ssh a@b".  For example, '"ssh a@b bash -l -c
> 'commands'" and "ssh a@b source /etc/profile; commands" both work for
> me.  I only wish I could "ssh a@b commands" and have it work.  I've got
> the info I need to figure out a different solution, though.  Thanks!

If you set up your variables in ~/.bashrc instead of /etc/profile, that
should get executed on every bash invocation (assuming your remote shell
is "bash").
	Igor
-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_		pechtcha@cs.nyu.edu
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     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski, Ph.D.
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

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