Possible regresion of issue 771

[edubxb]

Bug Report

Current Behavior

Same as described in issue #771

Expected Behavior

Same as described in issue #771

Additional context/Screenshots

No error with version 0.32.2, with other newests versions, the issue occurs.

Environment

• Starship version: 0.33.1
• Shell type: bash
• Shell version: GNU bash, version 5.0.11(1)-release (x86_64-pc-linux-gnu)
• Shell plugin manager: bash-it
• Terminal emulator: Tilix
• Operating system: Debian Testing

Relevant Shell Configuration

https://github.com/edubxb/dotfiles/blob/master/.bashrc

Starship Configuration

https://github.com/edubxb/dotfiles/blob/master/.config/starship.toml

[chipbuster]

Sorry about being slow on the uptake here.

I'm eyeing #799 as a possible culprit here. I'd suspect that the cuplrit is a command which appends to PROMPT_COMMAND without checking to see if there's already a semicolon on the end.

Could you share the output of echo $PROMPT_COMMAND? That'll at least get us started in figuring out what's going on.

[edubxb]

Hi, no worries.

My current PROMPT_COMMAND value:

_direnv_hook;__vte_prompt_command;starship_precmd;preexec_invoke_cmd

The components are:

• _direnv_hook: added by direnv
• __vte_prompt_command: added by the vte script from libvte Debian package
• starship_precmd: I think you already know this 😉
• preexec_invoke_cmd: added by Bash-it

[chipbuster]

Huh, so I guess I'm wrong.

Can you post the exact error message you get? Does it also occur on line 8 with ``(_z --add "$(command pwd -P 2>/dev/null)" 2>/dev/null &)`, or is there a different message that gets displayed?

[edubxb]

The error:

bash: PROMPT_COMMAND: line 0: syntax error near unexpected token `;;'
bash: PROMPT_COMMAND: line 0: `_direnv_hook;__vte_prompt_command;starship_precmd;;preexec_invoke_cmd'

The PROMPT_COMMAND value:

_direnv_hook;__vte_prompt_command;starship_precmd;;preexec_invoke_cmd

[chipbuster]

Damned if we do, damned if we don't. (Thanks for telling me where the commands come from by the way--that ended up being very helpful).

This is caused by #799, which looks like it was intended to avoid this kind of problem in the first place. (See the discussion on #784 for details).

It seems that there's no solid convention for whether you throw a semicolon on the end or not.

@InNoobWeTrust Should we consider this a bug on our end or should we file something against bash-it? If it's a bug, it probably in the safe_append_prompt_command function in bash-it.

[InNoobWeTrust]

@InNoobWeTrust Should we consider this a bug on our end or should we file something against bash-it? If it's a bug, it probably in the safe_append_prompt_command function in bash-it.

My personal opinion is that one who mess with PROMPT_COMMAND should do proper check, so bash-it should be aware this kind of problem, like direnv and pyenv did (just my hypothesis without actually looking at the code, but they never break my system)...

BUT, there is still hope, we may fix this ourselves with a little trick!
I'm thinking about this for quite a day and right before going to bed (after Lunar New Year eve here 😛), an idea came out. It's weird but seems like it can help us at this:
(DISCLAIMER: not for the faint hearted)

❯ echo hello; nop(){ $@; unset -f nop; } && nop
hello

~
❯ echo hello; nop(){ $@; unset -f nop; } && nop echo bug
hello
bug

~
❯ nop
The program nop is not installed. Install it by executing:
 pkg install graphviz

~
❯

Practically, instead of just terminating ours, we can pull the trigger and release our alien nop command into theirs so whatever they throw at us (oh, I miss the lemons 😋) we can still be safe (and enjoy lemon juice, of course).

This can create debate and I haven't checked if it complies to POSIX but it works for bash, at least on Termux (on Android).

I can't guarantee that this is bug-free (our alien command isolate their command in a subshell), so may issues on their side arise if they rely heavily on current shell env (eg. they add 2 separate commands that are tightly coupled, but it's insane of them to do so).

What is your opinion, @chipbuster? Do we have enough courage to try this or we prefer being safe and file a bug report to bash-it?

[chipbuster]

@InNoobWeTrust My general feel is to prefer straightforward methods over clever hacks. We don't even have to formally file a bug report (yet), we can just ask what their preferred method for handling this is. If it turns out that they don't have a workaround and refuse to fix this, we can definitely look into

like direnv and pyenv did (just my hypothesis without actually looking at the code, but they never break my system)

We haven't seen breakages, but this isn't a 100% guarantee that they won't, since those tend to be loaded earlier in the PROMPT_COMMAND order. It seems this problem pops up if there's a rogue command being loaded before something else, so commands that show up early in PROMPT_COMMAND aren't as likely to be affected.

Also, Happy New Year! 🎆

[InNoobWeTrust]

Forgot to say, we can suggest them to try our current method in their code. Since the situation is the same with us.
safe_append_prompt_command#L526

[edubxb]

Until this issue be properly fixed, I applied this simple workaround:

Adding this at the end of my .bashrc

PROMPT_COMMAND=${PROMPT_COMMAND/;;/;}

[InNoobWeTrust]

Continue digging google for similar issues today, I found out that we can instead use \n as the separator instead of ; and everything will still work like normal.

Ref: Bug 704960 - /etc/profile.d/vte.sh overwrites PROMPT_COMMAND

For bash/zsh, $'\n' is needed for newline to be correctly interpreted

PROMPT_COMMAND=${PROMPT_COMMAND:+$PROMPT_COMMAND$'\n'}'starship_precmd'$'\n'

Midnight commander also uses this approach in their repo
src/subshell/common.c#L828

Test on Debian

❯ echo -e "$PROMPT_COMMAND"
starship_precmd;_pyenv_virtualenv_hook;

❯ PROMPT_COMMAND=${PROMPT_COMMAND:+${PROMPT_COMMAND}$'\n'}'date'$'\n'
Thu 30 Jan 2020 03:53:22 PM +07

❯ echo -e "$PROMPT_COMMAND"
starship_precmd;_pyenv_virtualenv_hook;
date

Thu 30 Jan 2020 03:53:25 PM +07

❯ PROMPT_COMMAND=${PROMPT_COMMAND:+${PROMPT_COMMAND}$'\n'}'echo hello'$'\n'
Thu 30 Jan 2020 03:53:31 PM +07
hello

❯ echo -e "$PROMPT_COMMAND"
starship_precmd;_pyenv_virtualenv_hook;
date

echo hello

Thu 30 Jan 2020 03:53:33 PM +07
hello

How do you guys think about this? If this is good enough, I'm going to make a pull request. 😉

[edubxb]

LGTM

[chipbuster]

Problem discussion continued (and eventually resolved) on #890