Use /bin/bash in shebang for better cross-system compatibility

[Daja177]

Not all UNIX-based systems have Bash at /usr/bin/bash. On some Linux distributions and macOS, it may be located elsewhere (such as /bin/bash). Using /usr/bin/env bash lets the system find Bash via PATH, so the script runs more reliably across environments.

This change is also relevant to pull request #17, which aims to improve cross-platform compatibility (including environments where GNU tools or newer Bash versions may not be available by default).

[tatsumoto-ren]

Hello! Yes, I don't know why we use /usr/bin/bash here. Luke Smith uses /bin/bash and /bin/sh instead.

• LukeSmithxyz/voidrice@2b5df86
• #!usr/bin/env sh shebang LukeSmithxyz/voidrice#1269
• Use /usr/bin/env * instead of /bin/* LukeSmithxyz/voidrice#355 (comment)

  I wonder if there is a system out there that doesn't have /bin/sh but has /usr/bin/env (even NixOS has /bin/sh).

I also use /bin/sh and /bin/bash in my dotfiles https://github.com/tatsumoto-ren/dotfiles/tree/main/.local/bin

[Daja177]

Thanks, this is definitely an improvement 👍

One concern with #!/bin/bash though, it still hardcodes the path. On non-Linux UNIX systems where Bash isn't installed by default, it often ends up somewhere like /usr/local/bin (e.g. on FreeBSD), so it wouldn't be picked up there. The change in LukeSmithxyz/voidrice@2b5df86 makes sense for sh since /bin/sh is guaranteed, but that doesn't apply to Bash.

On macOS, /bin/bash is an older version incompatible with the current version of impd (this might change if #17 is accepted), so a newer Bash needs to be installed (e.g. via Homebrew in /opt/homebrew/bin), which wouldn't be used with #!/bin/bash.

Using #!/usr/bin/env bash lets the system pick the right Bash from PATH, which makes it work across more setups. Would you be open to that instead?

[tatsumoto-ren]

One concern with #!/bin/bash though, it still hardcodes the path. On non-Linux UNIX systems where Bash isn't installed by default, it often ends up somewhere like /usr/local/bin (e.g. on FreeBSD), so it wouldn't be picked up there. The change in LukeSmithxyz/voidrice@2b5df86 makes sense for sh since /bin/sh is guaranteed, but that doesn't apply to Bash.

I see. Do you think #!/usr/bin/env bash is better? The main argument against it is that it takes more time to execute because it needs to find where bash is.

On macOS, /bin/bash is an older version incompatible with the current version of impd (this might change if #17 is accepted), so a newer Bash needs to be installed (e.g. via Homebrew in /opt/homebrew/bin), which wouldn't be used with #!/bin/bash.

I think #17 can't be accepted as is because it removes some really handy bash-isms. I would rather try to find a way to run the latest version of GNU bash on macOS.

The question is, does /opt/homebrew/bin get added to the PATH? If not, #!/usr/bin/env bash would make no difference.

We could add this check to impd so it doesn't run on old Bash versions:

if [[ ${BASH_VERSION%%.*} -lt 5 ]]; then
      echo "Bash version is older than 5"
      exit 1
fi

[Daja177]

I ran a few benchmarks on my system, and the difference between #!/usr/bin/env bash and #!/bin/bash was only a few milliseconds at most per run, so it's negligible in this case.

The question is, does /opt/homebrew/bin get added to the PATH? If not, #!/usr/bin/env bash would make no difference.

On macOS, adding the Homebrew prefix to PATH is a required step for Homebrew to work. The installer explicitly tells users to update their shell config so the Homebrew prefix is added to PATH. As mentioned earlier, #!/usr/bin/env bash also helps on systems like FreeBSD where Bash is typically installed in /usr/local/bin.

The Bash version check you suggested is a good idea as long as impd continues to depend on Bash 5+ features.