Kernel fails to load when using non-standard interactive shells such as fish

[Ilazki]

When using the non-POSIX compliant fish shell, attempting to load the ocaml-jupyter kernel fails repeatedly with messages of ocaml-jupyter-kernel: 1: set: Illegal option -g. The problem here is that opam is fish-aware and, if it detects it as your shell, opam config env emits commands of set -gx to set environment variables, which is valid in fish but not in sh/bash/etc. That means the line in kernel.json that starts with eval $(opam config env --switch=<switch>) is failing to execute properly on kernel start because it's running /bin/sh but opam is emitting fish shell syntax and causing sh to error out.

This is fixed by adding --shell=sh to the opam arguments (e.g. eval $(opam config env --switch=<switch> --shell=sh)), which forces it to emit sh-compliant environment variable setting instead of attempting to intelligently detect the correct shell. If I do this manually and then install the kernel everything works as expected.

Judging by the error messages, I think this may also be the source of the unsolved bug report #110 as well. It was closed after the submitter worked around the problem by using docker, which bypassed the bug but never actually solved it.

[Ilazki]

@mseri: I know it still has to get merged but wow, that was a fast response. Thanks ;)