Allow shell variables in .yarnrc

[HaleTom]

Feature (supported by npm)

Current behavior

npm allows in the .npmrc:

prefix=${XDG_DATA_HOME}/npm

However, when I type in my shell:

yarn config set prefix '${XDG_DATA_HOME}/npm'

I see this in my ~/.yarnrc:

prefix "/home/ravi/.local/share/npm"

What is the expected behavior?
.yarnrc contains:

prefix "${XDG_DATA_HOME}/npm"

Please mention your node.js, yarn and operating system version.

$ node --version
v8.5.0
$ yarn --version
1.1.0
$ uname -a
Linux svelte 4.9.52-1-MANJARO #1 SMP PREEMPT Wed Sep 27 16:40:38 UTC 2017 x86_64 GNU/Linux

[HaleTom]

Will likely be required in conjunction with #2334.

[paul-soporan]

Closing as v2 allows environment variables to be used in .yarnrc.yml files.

https://yarnpkg.com/getting-started/migration