Minimum bash and zsh version requirements

[HaleTom]

I'm writing code which may use newer features in both shells.

What is the project's standard for the version of each shell with which we need to be compatible?

[HaleTom]

In particular, this:

# Quote "$@" before `eval` to prevent arbitrary code execution.
# Eg, the following will run `date`:
# evil() { eval "$@"; }; evil "echo" "foo;date"
function _safe_eval() {
  if [[ $shell = bash ]]; then
    # ${parameter@operator} where parameter is ${@} and operator is 'Q'
    # https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
    eval "${@@Q}"
  else  # zsh
    # http://zsh.sourceforge.net/Doc/Release/Expansion.html#Parameter-Expansion-Flags
    eval "${(q-)@}"
  fi
}

[ghthor]

I vote we just set the minimum version to "very-modern", mark any case we know about where were using a feature with it's minimum version requirement and then let anyone that needs support in an older shell work through any of those issues.

TL:DR; Use modern features, especially if they improve security and safety.

[ghthor]

My shell on my work laptop is. I'm pretty sure I can override that with a newer version through homebrew if I need too.

GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin17)

[HaleTom]

Given no answer, I'm going to declare that:

scm_breeze should work on the versions of shells in Ubuntu 14.04.5 LTS "Trusty Tahr" (end of support April 2019)

Those versions are:

bash: 4.3.11(1) zsh: 5.0.2

I guess I'll go and re-write the above quoted code :(

I'll close this issue in a week so that it has a little more visibility until then. If I forget, then please do the honours for me ;)

[ghthor]

Wouldn't mind leaving a nasty warning messaging in there when your shell is old enough to lack this support. You version selection decision seems solid to me.

[ghthor]

Also, I'm sorry this has taken longer then maybe you were expecting. I am seriously excited and very thankful to have your contributions.

[HaleTom]

I'm now getting 3/4 green on Travis CI.

The limiting factor is actually zsh on Ubuntu 14.04, which is supported until April 2019.

I'll edit my "declaration" above.

[HaleTom]

@ghthor While the versions of shells on Ubuntu 14.04 are sufficient, the aren't necessarily minimal, so I'd prefer to avoid an incorrect error message.

[ghthor]

Between this an the nightmare of shell I take care of at work I really like the idea of building a polyfill library for shell, ala the javascript(or older project) style. Come to think of it JS runtimes and Shell runtimes kind of share a similar type of problem. Both can have wildly different support and settings from system to system.

[HaleTom]

I don't know if there would be a way to ensure that you don't do:

local array=(x y z)

via a library.

It's just a thing that zsh 5.0.2 requires:

local array
array=(x y z)

Even shellcheck won't point this out as it's zsh specific. Having said that, shellcheck is highly recommended for everything else :)

(This took 24 travis builds to work out!)

[ghthor]

Shfmt enforcement and shellcheck linting are on my end of 2018 timeline for .scm_breeze, going to make this happen.