Question about ssh-askpass

Daiki Ueno ueno at
Sat May 6 23:41:55 EST 2000

>>>>> In <Pine.LNX.4.21.0004291824010.816-100000 at> 
>>>>>   Damien Miller <djm at> wrote:

> > I'd like to use ssh as a subprocess, and I'm looking for a generic way
> > of passing passphrase. So far as I know, in SSH Communications'
> > implementation of SSH, ssh invokes ssh-askpass as well as
> > ssh-add does. Lacking of this is just because of security reason?
> >
> > Are there any plans to use some kind of readymade option parsing
> > routine--such as getopt?

> No. If passwords were passed in on the command line, then they would
> show up to everyone else on the system in a "ps".

I'm sorry for my illegible sentences above.
There are no tie-in between these two questions. 

On the first question, create a new file contains following:

| #include <sys/ioctl.h>
| #include <unistd.h>
| int main (argc, argv)
|         int argc;
|         char *argv[];
| {
|         ioctl (0, TIOCNOTTY, 0);
|         close (0);
|         execvp (argv[1], &argv[1]);
|         return 0;
| }

and compile it:

% gcc -o test test.c

% ./test ssh ueno at suzuran ls

SSH Version 1.2.27 pops up ssh-askpass, but OpenSSH just exits with
"You have no controlling tty.  Cannot read passphrase."

As far as I know, `call-process' (the Emacs synchronous subprocess
function) can also detach the child's controlling terminal.

So, with using vc.el with CVS_RSH=ssh, I could input passphrase via

> You could either use ssh-agent or create key files without 
> passphrases.

Of course, I know that.

Daiki Ueno

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