mc ignores $PS1 on macOS

[mivk]

Is there an existing issue for this?

• I have searched the existing issues

Midnight Commander version and build configuration

GNU Midnight Commander 4.8.33
Built with GLib 2.82.4
Built with S-Lang 2.3.3 with terminfo database
Built with libssh2 1.11.1
With builtin editor
With subshell support as default
With support for background operations
With mouse support on xterm
With internationalization support
With multiple codepages support
Virtual File Systems:
 cpiofs, tarfs, sfs, extfs, ftpfs, sftpfs, shell
Data types:
 char: 8; int: 32; long: 64; void *: 64; size_t: 64; off_t: 64; uintmax_t: 64;

Operating system

Darwin cat.andromeda.lan 24.5.0 Darwin Kernel Version 24.5.0: Tue Apr 22 19:54:25 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6020 arm64

(MacOS 15.5)

Is this issue reproducible using the latest version of Midnight Commander?

• I confirm the issue is still reproducible with the latest version of Midnight Commander

How to reproduce

When I start mc, it ignores the PS1 variable I had exported, and resets the prompt to bash-3.2$.

This is on MacOS 15.5, with the default shell set to Bash (v. 3.2.57 on Mac)

In .profile, I set PS1 as:

export PS1='\[\e]2; $PWD \a\e[32;1m\]\h:$PWD/$\[\e[0m\] '

But when I start mc, I have:

bash-3.2$ echo $PS1
\s-\v\$
bash-3.2$ 

I must re-execute the export PS1=... command to get back my prompt (though without the colors, but that is ok).

Expected behavior

The mc subshell should keep the value of $PS1

Actual behavior

$PS1 gets replaced.

Additional context

I don't have this problem on a different machine with MacOS 15.5 but with Midnight Commander version 4.8.28

[zyv]

I don't have this problem on a different machine with MacOS 15.5 but with Midnight Commander version 4.8.28

Could you confirm whether it works on this machine with version 4.8.28, and perhaps identify the problematic commit using bisect?

I don't recall there being any changes to that effect. Ideally, I would like to exclude situations where .profile simply doesn't get executed or PS1 is overwritten by the system, as is the case with Alpine, for example.

Otherwise, could you provide a way to reproduce the issue? I have the latest macOS with zsh as the default shell.

[zyv]

Actually, after rereading the code, I'm not quite sure what works for you on the machine where you think it does.

As I understand it, historically, mc used to simply overwrite PS1 for all subshells to provide the same behavior, irrespective of the shell and user settings. Later, support for initialization was added, which probably "broke" the overriding. However, nobody noticed, thinking it was a feature. Or maybe the PS1s were left as fallbacks in case they aren't defined during initialization.

https://github.com/MidnightCommander/mc/blob/master/src/subshell/common.c#L1169

See the code for bash, zsh, and tcsh — they all define PS1. An exception was made for fish because it's extremely different from other shells.

Recently, support for ksh was introduced, affecting all subshells using the precmd emulation fallback (ash and dash). Confusingly, this code exists with the explicit aim of respecting the user's PS1.

I created ticket #4634 to clean this up, but I never had time to dive into this terrible rabbit hole again.

[mivk]

On the machine with MC v. 4.8.28 where PS1 was preserved, I upgraded MC to 4.8.33.

Now the prompt gets reset when MC is started, like on the other Mac.

I used brew for the initial install of MC, and for the upgrades. Reverting to an older version of a Homebrew package seems to be quite complex, so I'm afraid I will not try to do that. (Unless there is a pre-compiled Mac package which I can download directly from somewhere).

Anyway, since you say it is "normal" that PS1 gets redefined by MC, then maybe this is not a bug and maybe it should actually be a feature request: "Do not touch PS1" ?

[zyv]

On the machine with MC v. 4.8.28 where PS1 was preserved, I upgraded MC to 4.8.33.

Now the prompt gets reset when MC is started, like on the other Mac.

I used brew for the initial install of MC, and for the upgrades. I'm not sure if I can revert to a previous version using brew. WIll have a look.

Okay, thanks for confirming that. It would be great if you could bisect the commit that broke it:

brew install autoconf automake gettext libtool pkg-config glib s-lang

git clone https://github.com/MidnightCommander/mc.git

cd mc

git bisect start 4.8.33
git bisect good 4.8.28

Now do ./autogen.sh && ./configure --prefix=$(pwd)/install && make && make install and test with ./install/bin/mc, then say git bisect good (if it works correctly) or git bisect bad. After a few iterations it will tell you exactly which commit broke it.

Anyway, since you say it is "normal" that PS1 gets redefined by MC, then maybe this is not a bug and maybe it should actually be a feature request: "Do not touch PS1" ?

I'm not sure (see above). It's strange that the situation changed. I wonder if it really has to do with MC or how bash on macOS initializes.

[zyv]

@mivk so were you able to find anything out yet?

[d3m3t3r]

But when I start mc, I have:

bash-3.2$ echo $PS1
\s-\v\$
bash-3.2$ 

mc is certainly not setting bash prompt to "\s-\v$" (see https://github.com/MidnightCommander/mc/blob/4.8.33/src/subshell/common.c#L1135). My guess is your shell is not recognized as bash and PS1 is overwritten during initialization of the shell (hardcoded default?).

I must re-execute the export PS1=... command to get back my prompt (though without the colors, but that is ok).

That's an odd claim. If you change your prompt in the mc subshell (...generally not recommended) it will change to the new value just like it would outside of mc.
If you mean the prompt you see "in mc" (aka on "Command prompt" line), then it's even more complicated as this prompt is some sanitized version of the prompt detected by mc when the subshell is started. All ANSI colors would be removed there.