Emacs: Tramp doesn't work

Asked 5/8, 2011 at 9:52 Answered 9/7, 2020 at 23:9

I tried to open a remote file via Emacs via Tramp.

(require 'tramp)
(setq tramp-default-method "ssh")

I get a message from Emacs

Tramp: Waiting for prompts from remote shell

Emacs hung and did not respond to any action after that

Emacs was installed on Windows; the remote file was on a Linux machine.

Cirque answered 5/8, 2011 at 9:52 Comment(3)

Which ssh client are you using on your Windows machine? – Grotto 5/8, 2011 at 12:11

If you do make this work, make sure to post your solution. As a long-time Emacs on Windows user, I've been unable to make tramp work reliably, even following the various wiki instructions out there. – Ligule 5/8, 2011 at 12:25

C-g does help to stop the hanging Emacs. – Accrescent 8/5, 2017 at 9:47

If the account you're connecting to uses some weird fancy shell prompt, then there is a good chance that this is what makes tramp trip.

PS1="> "

(that's a normal, standard shell (ZSH, BASH, younameit) prompt, one that tramp will understand) then switch to the user account, and launch emacs -q (to make sure that your .emacs is not causing this mess) and try to C-x C-f /sudo:root@localhost:/etc/hosts and see what's what.

You can (not recommended) also customize the regexp that defines what tramp expects :

M-x customize-variable RET tramp-terminal-prompt-regexp

My approach :

Make sure the variable tramp-terminal-type is set to "dumb"

M-x customize-variable RET tramp-terminal-type

Test that in your .*shrc and serve the correct prompt :

case "$TERM" in
"dumb")
    PS1="> "
    ;;
xterm*|rxvt*|eterm*|screen*)
    PS1="my fancy multi-line \n prompt > "
    ;;
*)
    PS1="> "
    ;;
esac

Fibrous answered 2/12, 2011 at 22:32 Comment(10)

Thank you! This must be the source of many people's problems and they just don't realize it. Fixed my Tramp bug which I thought was a lost cause. – Myotome 5/3, 2012 at 17:22

It is worth noting that you can customize the prompt that tramp expects (M-x customize-variable "tramp-login-prompt-regexp" but my advice would rather be to make your prompt tramp-compatible (github.com/xaccrocheur/kituu/blob/master/.bashrc) and not the other way around – Fibrous 1/6, 2012 at 19:29

Can I somehow check what prompt TRAMP sees and tries to match against? I'm a bit unsure what shell that is run and what configuration files that are read. – Aslam 23/10, 2012 at 12:15

@Nordlow: Yes, M-x customize-variable "tramp-terminal-prompt-regexp" – Fibrous 17/12, 2012 at 14:24

I want all this to be automated. Prompt pattern should be detected automatically for the remote host. How do we achieve this? – Aslam 17/12, 2012 at 22:12

We don't. At the remote end, the prompt can be anything, really. The user could have setup a strange 3 lines non-UTF8 oddity. I hear what you say, Tramp should be able to parse anything and arbitrarily state "this is the remote prompt" but AFAIK he can't. – Fibrous 18/12, 2012 at 8:33

This works for me, but the tests using C-x C-f /sudo:root@localhost:/etc/hosts did not work and returned a different error about sudo can only use the local host (I would have to configure multi-hop or something). If you altered the PS1 variable, I recommend trying out the "My approach" section directly, and save the sudo configuration for another day. – Swahili 11/6, 2014 at 1:46

If you're still having issues after fixing the .*shrc file, try restarting Emacs. For some reason this was necessary for me - my guess is that tramp reused the connection it had initially opened, which still used the non-dumb prompt. – Scanlan 22/10, 2014 at 16:16

Nobody mentioned the blocker I had: in case the shell is not interactive, the ~/.bashrc file returns immediately (by default in Gentoo). The "return" command should be removed. – Frothy 19/11, 2014 at 10:50

I wrote about it some time ago here because I had a lot of trouble to figure out what was the problem – Fairground 6/9, 2021 at 7:37

Your Windows ssh client is the key here, and the 'ssh' Tramp method is almost certainly wrong.

If you're using Cygwin, then you need to use the 'sshx' method, and you probably need to use ssh-agent to handle authentication. Details are here: Using tramp with EmacsW32 and cygwin, possible?

I imagine the same applies to any stand-alone ssh client which does not require a full Cygwin installation, but does use the Cygwin DLLs. (I mention this, because I'm pretty sure I remember seeing such a thing.)

If you're using PuTTY then you want the 'plink' method, as Alex Ott pointed out. If the Wiki doesn't suffice, a search here will probably turn up solutions for configuring that approach.

Other alternatives I can suggest are:

Use the Cygwin-native Emacs. That will be slower than NTEmacs, but Tramp seems to work well with the 'ssh' method, and password-prompting works as well.
Host a Linux VM on your Windows box, and run Emacs on that. That's a fairly large hoop to jump through, but it's my preferred way of using Tramp when working in Windows.

Grotto answered 5/8, 2011 at 12:19 Comment(0)

Well, this is a defect of tramp.

The real solution is to prevent loading .bashrc when tramp is used. (because now it is PS1, but it can be PATH, or any other thing that your .bashrc will do that will displease tramp...).

This can be done by asking ssh to set an environment variable, and testing it in .bashrc:

Add this to ~/.emacs:

(require 'tramp-sh nil t) (setf tramp-ssh-controlmaster-options (concat "-o SendEnv TRAMP=yes " tramp-ssh-controlmaster-options))

and that at the beginning of ~/.bashrc:

if [ ! -z ${TRAMP-x} ] ; then return fi

Another default of tramp is that it doesn't have a variable to pass random arguments to the ssh command, we have to piggy-back on tramp-ssh-controlmaster-options.

Coyote answered 2/8, 2018 at 15:23 Comment(1)

I like the explanation here, but isn't this approach similar to that in the most upvoted answer, except you're sending a custom environmental variable and not loading bash (seems reasonable) whereas that answer has the shell check the TERM environmental variable and load a simple prompt in the case of Tramp (also reasonable)? Just checking my understanding before trying an approach. – Sacrarium 26/11, 2019 at 17:33

Had you checked Emacs wiki for solution? ssh is in PATH? It's also recommended to use plink on MS Windows - see section "Inline methods" in Tramp documentation

Griffis answered 5/8, 2011 at 10:16 Comment(1)

Alex: Thanks, but unfortunately the documentation lacks an example there. Here it is: C-x C-f /plink:user@host:/path/to/file – Frothy 19/11, 2014 at 10:35

If the problem is your fancy custom prompt in the remote shell, an easy workaround is to add to your .bashrc or equivalent:

if [[ $TERM == "dumb" ]]; then
    export PS1="$ "
fi

After you define your PS1.

Note: the credit goes to ChasingLogic as this is their suggestion in this thread.

Quipster answered 9/7, 2020 at 23:9 Comment(1)

Prior art (just for the sake of completeness): blog.karssen.org/2016/03/02/… Original Emacs Wiki entry: emacswiki.org/emacs/TrampMode#h5o-9 – Jeroboam 14/12, 2021 at 18:48

By the way -- if You need tramp to sudo -- You can actually sudo without tramp using sudoedit.

Currently I'm using this bash function:

erf () { SUDO_EDITOR="emacsclient -a emacs" sudoedit $@; }

Varela answered 1/10, 2012 at 14:7 Comment(3)

The primary use of Tramp is not to sudo. – Idolum 23/4, 2013 at 16:43

Yep -- I should have made it a comment, not an answer -- but I was young and foolish. – Varela 24/4, 2013 at 4:59

@Varela and your name is a software company name. just saying – Ever 26/6, 2017 at 14:18

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