Re: Tramp hangs: unable to find stty binary

[Michael Albinus]

M J <address@hidden> writes:

Hi,

> I'm trying to connect to host that doesn't have a `stty` binary
> through tramp. Unfortunately, once it finds a shell, tramp tries to
> run stty and fails, repeating this indefinitely.
>
> I have put an stty binary which works on the remote host when I login
> with ssh, and have added it to PATH (root is on squashfs and
> read-only, stty binary is in /storage/bin). But trying to get tramp to
> also respect the PATH for stty is impossible. I have tried the
> following and all fail.
>
> =======
> (setq tramp-verbose 10)
> (add-to-list 'tramp-remote-process-environment
> "PATH=/storage/bin:/usr/bin:/usr/sbin")
> (add-to-list 'tramp-remote-process-environment
> "ENV='PATH=/storage/bin:/usr/bin:/usr/sbin'")
> (add-to-list 'tramp-remote-path 'tramp-own-remote-path)
> (add-to-list 'tramp-remote-path "/storage/bin")

When the remote shell is called, ENV is passed as argument. However,

> 22:16:23.530987 tramp-send-command (6) # exec env TERM='dumb'
> INSIDE_EMACS='26.3,tramp:2.3.5.26.3'
> ENV='PATH=/storage/bin:/usr/bin:/usr/sbin;HOME=/storage'
> HISTFILE=~/.tramp_history PROMPT_COMMAND='' PS1=\#\$\ PS2='' PS3=''
> /bin/sh

shows a different value of ENV, namely
'PATH=/storage/bin:/usr/bin:/usr/sbin;HOME=/storage'. Could you remove
this ';HOME=/storage' part?

> I would expect tramp to fail fast and fail hard when stty or any other
> required binary is not available with an appropriate message.

There is always a trade-off between testing everything, and
performance. Tramp expects a valid ssty w/o further checks. I could
improve this, of course, but with the penalty of decreasing performance.

> Also being able to specify alternate PATH is important in this case to
> find such binaries.

Tramp gives you this feature, via tramp-remote-path. But maybe is must
be set very early at the handshaking. OTOH, setting terminal options via
stty is a must in order to speek properly with the shell. Hmm.

> I'm not sure how to fix this issue and would appreciate any help.

> fengshaun

Best regards, Michael.