feat: allow overriding default $SHELL /bin/bash

[Congee]

Some systems do not have /bin/bash. e.g., Alpine and NixOS. This change allows the user to provide one's own path of bash to fzf. It solves the error fork/exec /bin/bash.

Note that fzf --preview 'xxxx' essentially executes $SHELL -c 'xxxx', so I tested on bash, zsh, and fish forgit::blame and it worked.

Check list

• [x] I have performed a self-review of my code
• [ ] I have commented my code in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

Description

Type of change

• [ ] Bug fix
• [x] New feature
• [ ] Refactor
• [ ] Breaking change
• [ ] Documentation change

Test environment

• Shell
  • [x] bash
  • [x] zsh
  • [x] fish
• OS
  • [x] Linux
  • [ ] Mac OS X
  • [ ] Windows
  • [ ] Others:

[carlfriedrich]

@Congee Thanks for your submission. I wasn't aware that bash could be available in different places. We cannot use your proposed solution, though, because we have to enforce usage of bash as a shell for the preview commands. Otherwise users that have set their SHELL to something different (e.g. fish) will have non-working preview in fzf.

How about this:

SHELL=$(which bash)

Would that work for you?

[Congee]

@carlfriedrich yo, I have updated this PR and the commit message as you suggested :grin: