Alternatives to --emulate-fhs on foreign distros

[Kyle Andrews]

Dear Guix,

The (many) shell scripts in my software depend on bashisms. In the code right 
now I typically use /usr/bin/env bash since I had read that was the most 
portable way of referencing a shell. However, I really don't think I have a 
good handle on what my choices are. Maybe the tedious solution of just typing 
`bash script.sh' in all of the system calls referencing this scripts might be 
the right approach in the long run?

Should I be aiming to automatically patch my source code to point to a specific 
bash? Why doesn't this happen automatically? Is there a way to upgrade from 
/bin/sh to bash within a shell script? I know I can use --emulate-fhs to ensure 
that /bin/bash and /usr/bin/env bash are available, but that seems to preclude 
including the software directly in Guix without a container.

I'm curious what other options might be. The main bashism I use is default 
environment variables ${FOO:-bar}. On a native Guix system I could just add 
/usr/bin/env back in. However, that doesn't seem to be possible with only Guix 
shell. Maybe I am wrong here?

Thanks,
Kyle