Bashix

Starting from these Shell Compatibility Reports:

• https://pages.oils.pub/spec-compat/2025-06-26/renamed-tmp/spec/compat/TOP.html

Here are some questions:

• What shell test suites exist?
  • Oils - incorporates some cases from toysh
  • We also run the Smoosh test suite, linked from our quality page
• Can tests be shared across shell implementations?
  • What's the success criteria? Bash oracle mode versus Assertions
  • What's the format of the tests, and the protocol? e.g. $SH vs. $TEST_SHELL
• Can we agree on what the shell language is?
  • It's not just POSIX anymore!
  • Maybe it's "Bashix" -- bash mksh ksh sush brush osh agree on hundreds of tests that other shells don't.
• Which constructs do shells disagree the most on? Some candidates:
  • The semantics of POSIX special Builtins
  • The semantics of unset
    • Survey from Koichi on Github (2020)
    • spec/ble-unset
    • spec/ble-features

Why care about this? I think shell users should have a well-defined language to write.

We can use the discussions and wiki to sort out these questions!

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Some more motivation:

Even BASH doesn't have 100% bash conformance. (Half my arguments with Chet cause version skew, which I see as a bug and he sees as a feature. I ask him to explain a corner case and he FIXES it, but then what do I put in the test suite ... ?

— Rob Landley (of toysh)