fix: keep the script compatible with Busybox applets

[folliehiyuki]

• Use short flags for sort command
• Remove -n flag for nl command. The numbers in the selection list won't be aligned anymore, but no information is lost.

The current arguments are only presented in GNU's coreutils.

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

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

Test environment

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