[ale] Scriptable motd for initial SSH login?

Michael H. Warfield mhw at WittsEnd.com
Wed Sep 14 16:38:49 EDT 2011


On Wed, 2011-09-14 at 16:37 -0400, Michael H. Warfield wrote: 
> On Wed, 2011-09-14 at 16:22 -0400, David Tomaschik wrote: 
> > On Wed, Sep 14, 2011 at 3:37 PM, James Sumners <james.sumners at gmail.com> wrote:
> > > Well, I had thought of that, but then I read [1] and it says:
> > >
> > > "SSHRC
> > >
> > >     If the file ~/.ssh/rc exists, sh(1) runs it after reading the environment
> > >     files but before starting the user's shell or command.  It must not pro-
> > >     duce any output on stdout; stderr must be used instead."
> > >
> > > This is explicitly counter to what I want to do so I didn't even
> > > bother trying it. But, since you guys have suggested it, I just tried
> > > adding the following to ~/.ssh/rc and logging in:
> > >
> > > #!/bin/bash
> > > echo -n "Does this work?\n"

> > Make sure you're outputting to stderr, not stdout.  The man page
> > wasn't kidding about that.  If you output to stdout, then programs
> > that use SSH as a transport will be broken because they'll see the
> > output of your script in their data stream.  (This includes rsync,
> > scp, etc.)

> Right.

> But that's the case even if you had another motd.

Actually, thinking about it, you might even check to see of /dev/tty
exists for you (that would be your "console" to a ptty) and if so write
straight to it.  If it doesn't, you might not want to do anything,
stdout or stderr, since you don't have a ptty allocated.

> > > Guess what? It worked. So, thank you for making me re-examine this option.
> > >
> > > [1] -- http://www.manpagez.com/man/8/sshd/
> > >
> > 
> > 
> > 
> > -- 
> > David Tomaschik, RHCE, LPIC-1
> > System Administrator/Open Source Advocate
> > OpenPGP: 0x5DEA789B
> > http://systemoverlord.com
> > david at systemoverlord.com
> 
> Regards,
> Mike

Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
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