bug#28139: 25.2; TRAMP vs bash 4.4 / readline 7.0 "bracketed paste" mode

[Daniel Pittman]

On Sat, Aug 19, 2017 at 1:59 PM, Michael Albinus <michael.albinus@gmx.de> wrote:

> After upgrading a remote system to a version of GNU/Linux that
> includes bash
> 4.4 (from Debian/testing), with the readline option `set
> enable-bracketed-paste on` in /etc/inputrc, and no personal inputrc,
> tramp breaks.

Many different shells are busy to break Tramp.

Believe me, I know the pain.  This isn't my first time poking into the internals of how TRAMP hits remote shells.

 

> Passing the `--noediting` option to the remote shell command resolves
> the problem, by disabling readline entirely, but it should also be
> possible to augment the
> `tramp-open-connection-setup-interactive-shell` to issue,
> unconditionally, the command:
>
>     bind 'set enable-bracketed-paste off'

Does it help to add the following line into your remote ~/.bashrc:

[ $TERM = "dumb" ] && bind 'set enable-bracketed-paste off'

Alas, no, and the bash(1) man page "INVOCATION" section makes it clear why:

    Since a shell invoked as sh does not attempt to read and 

    execute commands from any other startup files, 

    the --rcfile option has no effect.

Interactive testing confirms this: if I invoke the shell the as TRAMP does, with:

env ENV='' HISTFILE='' HISTFILESIZE=0 HISTSIZE=0 PROMPT_COMMAND='' PS1=\#\$\  PS2='' PS3='' /bin/sh 

...then strace confirms that no init files are read, other than /etc/inputrc

So, it's not possible to work around this issue without injecting additional code into the shell setup process, using `/bin/sh --noediting`, or using an interactive shell and adding that to the .profile or equivalent.

note: --noediting has been present since bash 2.0 according to their changelog, so it may be reasonable to add by default to the non-interactive shell invocations.

Ultimately, though, perhaps adding the ability to run additional commands during the interactive shell setup process and/or consuming any CSI sequences prior to matching, would be a more future-proof solution to this.