Fix shebangs to #!/usr/bin/env bash in all .sh files

[cheriimoya]

This allows all scripts to be run without hardcoding /bin/bash as an interpreter.
Maybe this is an improvement, maybe not.
Someone should take a look at https://unix.stackexchange.com/a/29620 and document a decision for/against /bin/(ba)sh vs /usr/bin/env bash

Checklist:

• I added a summary of any user-facing changes (compared to the last release) in the changelog-entries/<PRnumber>.md. -> will probably not affect many users (at least not any users using debian/ubuntu)
• I will remember to squash-and-merge, providing a useful summary of the changes of this PR.

[davidscn]

Maybe this is an improvement, maybe not.

I would be in favor of using env for this purpose. We had already similar issues in ASTE. Problem: on compute clusters, the hardcoded path might not lead to the version you actually want to use. Here, env takes care of this.

The only change I am not sure about is that you changed the requirement from a POSIX shell to bash. Why not using #!/urs/bin/env sh instead?

[MakisH]

I thought of this while first creating all these scripts (or at least when making them consistent, in their current version), but I don't remember why I decided to keep the hard-coded path.

If this has already triggered issues, then let's indeed change it. The version argument is a valid one, apparently not only for clusters, but also for macOS.

However, I agree with @davidscn: I chose sh instead of bash as the most portable option, and we have invested some effort to keep scripts compatible with sh. Remember that some people use zsh, some csh, some ksh. Not all shells are compatible with bash. Let's keep it as sh.

[cheriimoya]

Okay, so this time it's using #!/usr/bin/env sh everywhere

[cheriimoya]

But interesting: Look at the failing pipeline!

[davidscn]

To be more concise with my previous comment: the way we call the shell should not alter the shell environment. Not all scripts are POSIX compatible.

[MakisH]

I agree with David: it is intentional that most scripts are sh but a few are bash. In any case, the kind of shell is not something we should change here.

[cheriimoya]

Okay, I've split the commit in two parts. Now I got what you meant @davidscn :D
Also grep'ed for /urs;)

Commands I used for reference: sed 's~#!/bin/sh~#!/usr/bin/env sh~' $(rg '#!/bin/sh' -l) -i (rg is ripgrep which is roughly equivalent to grep -r)

[davidscn]

Thanks!