About env var evaluation (documentation)

[yangm97]

It may be obvious to some but, due the way evaluation works, you need to escape characters such as & in double quotes, otherwise evaluation fails silently and the variable doesn't get set.

For instance, this works:

devshells.default.env = [
  {
    name = "MY_VAR";
    eval = "\"foo & bar\"";  # Wrap in quotes to ensure it's passed correctly
  }
];

But this doesn't:

devshells.default.env = [
  {
    name = "MY_VAR";
    eval = "foo & bar";  # Shell builds and loads but MY_VAR won't be shown in the export list, in addition to not being set   
  }
];