Re: specifying identity file for scp within tramp

[Barry Margolin]

In article 
<a909c8b8-f6ee-4e4a-ab51-523b2408b192@35g2000pry.googlegroups.com>,
 À¯×°×² <girzel@gmail.com> wrote:

> On Dec 22, 12:00 am, Barry Margolin <bar...@alum.mit.edu> wrote:
> > In article
> > <50944d4c-7190-41f4-90ec-17755ab0b...@k36g2000pri.googlegroups.com>,
> >
> >
> >
> >  À¯×°×² <gir...@gmail.com> wrote:
> > > On Dec 20, 9:45 am, Barry Margolin <bar...@alum.mit.edu> wrote:
> > > > In article
> > > > <b4647b13-f390-48aa-9373-46192b1bb...@b41g2000pra.googlegroups.com>,
> >
> > > >  À¯×°×² <gir...@gmail.com> wrote:
> > > > > On Dec 19, 1:38 pm, Barry Margolin <bar...@alum.mit.edu> wrote:
> > > > > > In article
> > > > > > <97c43290-2786-4b18-aaa8-429005829...@s9g2000prm.googlegroups.com>,
> >
> > > > > >  À¯×°×² <gir...@gmail.com> wrote:
> > > > > > > Can anyone tell me if it's possible to direct tramp to use a
> > > > > > > particular set of ssh keys when connecting to a particular 
> > > > > > > server? I'm
> > > > > > > trying to use scp with the equivalent of the -i option, what I 
> > > > > > > tried
> > > > > > > below just seems to confuse tramp, is there some other way I 
> > > > > > > should be
> > > > > > > doing this?
> >
> > > > > > > (add-to-list 'tramp-default-method-alist
> > > > > > >               '("remote_server" "" "scp -i /Users/my_user/.ssh/
> > > > > > > my_key"))
> >
> > > > > > Why not use the IdentityFile directives in ~/.ssh/config?
> >
> > > > > I'm already using a set of keys for regular ssh login, and there's a
> > > > > passphrase on that set. I was trying to create a second set
> > > > > specifically for tramp to use, with no passphrase and restricted
> > > > > permissions on the server side. So far as I know, I can only provide 
> > > > > a
> > > > > single IdentityFile per host in ssh/config -- do you know of any 
> > > > > other
> > > > > ways to automatically distinguish the proper keys for tramp to use
> > > > > with my server?
> >
> > > > I think you have to define a new method.
> >
> > > > (defvar my-scp-extra-args '("-i" "/Users/my_user/.ssh/my_key"))
> > > > (let* ((scp-method (assoc "scp" tramp-methods))
> > > >        (new-method (copy-tree (cdr scp-method)))
> > > >        (login-args (assoc 'tramp-login-args new-method))
> > > >        (copy-args (assoc 'tramp-copy-args new-method)))
> > > >   (setf (cadr login-args)
> > > >         `(,@my-scp-extra-args ,@(cadr login-args))
> > > >         (cadr copy-args)
> > > >         `(,@my-scp-extra-args ,@(cadr copy-args)))
> > > >   (push `("myscp" . ,new-method) tramp-methods))
> >
> > > > Then set the default method for remote_server to "myscp".
> >
> > > Thanks for this! I'm going to ask a fairly stupid follow-up question.
> > > I put this in my emacs, but it raised this error "void variable tramp-
> > > methods". I thought maybe you had to quote tramp-methods, but after I
> > > did it started raising "Wrong type argument: listp, tramp-methods".
> > > I'm not quite sure where to go from here. If I'm running 22.3.1, I
> > > shouldn't have to have (require 'tramp) at the top of my .emacs,
> > > should I? I added that, for the heck of it, and it started complaining
> > > about other tramp-related variables being undefined elsewhere in
> > > my .emacs file.
> >
> > > Sorry to chump out, hoping for a little more help...
> >
> > You probably need to put:
> >
> > (load "tramp")
> >
> > before this, so that the variable will be defined.  It's not normally
> > defined until tramp is auto-loaded.
> 
> Turns out my main problem was reading the docs for tramp 2.1.14 while
> actually using tramp 2.0.9. Updated tramp and all is working, though I
> had to change these two lines
> 
> `(,@my-scp-extra-args ,@(cadr login-args))
> `(,@my-scp-extra-args ,@(cadr copy-args)))
> 
> to this
> 
> `(,my-scp-extra-args ,@(cadr login-args))
> `(,my-scp-extra-args ,@(cadr copy-args)))
> 
> Since login-args is supposed to be a list of lists. Not sure if that
> was the proper way to do it, but it works.

I have temp 2.0.58-pre, and login-args is just a list.  Here's what the 
two entries in tramp-methods look like:

("myscp"
  (tramp-connection-function tramp-open-connection-rsh)
  (tramp-login-program "ssh")
  (tramp-copy-program "scp")
  (tramp-remote-sh "/bin/sh")
  (tramp-login-args
   ("-i" "/Users/my_user/.ssh/my_key" "-e" "none"))
  (tramp-copy-args
   ("-i" "/Users/my_user/.ssh/my_key"))
  (tramp-copy-keep-date-arg "-p")
  (tramp-password-end-of-line nil))
 ("scp"
  (tramp-connection-function tramp-open-connection-rsh)
  (tramp-login-program "ssh")
  (tramp-copy-program "scp")
  (tramp-remote-sh "/bin/sh")
  (tramp-login-args
   ("-e" "none"))
  (tramp-copy-args nil)
  (tramp-copy-keep-date-arg "-p")
  (tramp-password-end-of-line nil))

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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