If you're a zsh user there is a fun^wquirky way to achieve similar functionality using the MULTI_FUNC_DEF¹ option. zsh allows you to define multiple functions at the same time, so you can parametrize functions with something like:

    build_ssh qa_ssh test_ssh() {
        echo ${(U)0%_*}_SYSTEMIP
    }
    build_ssh  # Produces BUILD_SYSTEMIP
    qa_ssh  # Produces QA_SYSTEMIP

(You'd need the 'P' flag to perform secondary expansion to get the value of *_SYSTEMIP if you were using this for the same reason as in the post).

You can even use brace expansion in your function definition, iff you define it using the function keyword like "function {build,qa,test}_ssh()".

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There might be a nice solution to this with fish too, as you could create per-machine symlinks in your ~/.config/fish/functions to add a new machine.

¹ https://zsh.sourceforge.io/Doc/Release/Options.html