Warn if bash is not installed

[robertmassaioli]

Issue description

When bash was not installed, I got this error:

╭─ ~/.zsh-custom/plugins/nix-shell on master✔ 22-01-12 - 10:31:31 [0]
╰─⠠⠵ nix-shell -p myHaskellEnv
/nix/store/1fyqjwakpb5d8h52bwad3inn1r2zndhj-stdenv-darwin/setup: line 20: shopt: inherit_errexit: invalid shell option name
/private/tmp/nix-shell-23306-0/rc: line 1: rm: No such file or directory

I then ran brew install bash and it fixed things:

╭─ ~/.zsh-custom/plugins/nix-shell on master✔ 22-01-12 - 10:31:39 [1]
╰─⠠⠵ brew install bash
Running `brew update --preinstall`...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> Updated Formulae
Updated 1 formula.

==> Downloading https://ghcr.io/v2/homebrew/core/bash/manifests/5.1.16
######################################################################## 100.0%
==> Downloading https://ghcr.io/v2/homebrew/core/bash/blobs/sha256:85ac02733b659f4a7884395ed2cfd7dbdf59999a0d8a434a0c1a75085009ce2a
==> Downloading from https://pkg-containers.githubusercontent.com/ghcr1/blobs/sha256:85ac02733b659f4a7884395ed2cfd7dbdf59999a0d8a434a0c1a75085009ce2a?se=2022-01-11T23%3A40%3A00Z&sig=cGTa65Ck9peapQv9%2FDEs8QMrSWFKGWzkoEXgA2lpW
######################################################################## 100.0%
==> Pouring bash--5.1.16.catalina.bottle.tar.gz
🍺  /usr/local/Cellar/bash/5.1.16: 157 files, 10.9MB
==> Running `brew cleanup bash`...
Disable this behaviour by setting HOMEBREW_NO_INSTALL_CLEANUP.
Hide these hints with HOMEBREW_NO_ENV_HINTS (see `man brew`).
╭─ ~/.zsh-custom/plugins/nix-shell on master✔ 22-01-12 - 10:32:35 [0]

I highly recommend that a note be added to the readme for this use case. I have not investigated further why this is happening.

[chisui]

please add additional information to the ticket as specified in the template. In addition MacOS support is limited since I don't have the ability to test code on MacOS.

---

Does nix-shell work if you don't use this plugin?

[matejcik]

i'm seeing the same issue.
yes, nix-shell works without the plugin. it also starts working as soon as bash is installed

[chisui]

Ah, I forgot that I called bash explicitly in the code. I added a Warning message. Does v0.5.0 print Warning if bash is not installed?

[matejcik]

on commit af6f8a2, no warning message is shown.

[matejcik]

no, wait, the problem is that there is bash available, but it's version 3.2 so maybe too old? it doesn't know shopt inherit_errexit

Honestly not sure what to do here. You could detect bash version I suppose, but that sounds like a weird solution?
Alternately detect that you're on a Mac and that bash is /bin/bash, like:

if [ $(uname -s) == "Darwin" && $(which /bin/bash) == "/bin/bash"]; then
  echo "pls install newer bash via homebrew"
fi

The shopt call comes from nix itself so no way for us to modify that.

[matejcik]

maybe easiest to mention the problem in README and point to a solution there, so that it's easy to google.

[chisui]

Could you post the output of bash --version for the preinstalled bash?

---

I'm thinking of another solution like this right now:

if [ -z ${ZSH_NIX_SHELL_BASH_OVERRIDE+x}  &&  $(uname -s) == "Darwin" && $(bash --version | grep -q "3.2") ]; then
  echo "A well written warning"
  export ZSH_NIX_SHELL_BASH_OVERRIDE="command nix-shell -p bash --command"
fi

and then using that override in the shim.

[matejcik]

$ /bin/bash --version
GNU bash, version 3.2.57(1)-release (arm64-apple-darwin21)
Copyright (C) 2007 Free Software Foundation, Inc.

I can't say it's a good idea to rely on the exact string though -- an OS update could easily changed, this is on MacOS Monterey but I don't know about older versions, etc.

[chisui]

As far as I understand the bash license changed at some point and this is the latest Version Apple is allowed to ship with MacOS. So I don't think that either the 3.2 part nor the (c) 2007 part will change.