expose installation context into process

[cdaringe]

What is the current behavior?

Greetings!

npm exposes the following process.env.npm_config_global. this enables me to determine what context i am operating in during installation. i do not see such a thing present for yarn.

i understand that this could invoke some fear or questioning.

"why would you ever want or need that? you're probably doing something wrong!" --say concerned citizens

there's actually a plenty valid use case. my use case is that I have a package who's objective is to modify the consumer's package oninstall. because this pkg ships as a dep in other packages, some of which get installed globally, i care to detect this condition and respond accordingly.

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

• node 7.4.0
• yarn 0.18.1

[rally25rs]

Could be a good first contrib for someone; determine what env variables NPM makes available during script execution, and mimic them in Yarn.

oh ok, I'll do the first step... 👟

Add this script to package.json

  "scripts": {
    "test": "env | grep npm_"
  },

and then run npm test and get these env vars being set:

npm_config_save_dev=
npm_config_legacy_bundling=
npm_config_dry_run=
npm_config_viewer=man
npm_config_only=
npm_config_browser=
npm_config_also=
npm_config_rollback=true
npm_config_usage=
npm_config_globalignorefile=/Users/me/.nvm/versions/node/v8.0.0/etc/npmignore
npm_config_shell=/bin/bash
npm_config_maxsockets=50
npm_config_init_author_url=
npm_config_shrinkwrap=true
npm_config_parseable=
npm_config_metrics_registry=https://registry.npmjs.org/
npm_config_timing=
npm_config_init_license=ISC
npm_config_if_present=
npm_config_sign_git_tag=
npm_config_init_author_email=
npm_config_cache_max=Infinity
npm_config_long=
npm_config_local_address=
npm_config_git_tag_version=true
npm_config_cert=
npm_config_registry=https://registry.npmjs.org/
npm_config_fetch_retries=2
npm_config_versions=
npm_config_message=%s
npm_config_key=
npm_package_devDependencies_react=^15.6.1
npm_package_description=
npm_package_license=ISC
npm_config_globalconfig=/Users/me/.nvm/versions/node/v8.0.0/etc/npmrc
npm_config_prefer_online=
npm_config_logs_max=10
npm_config_always_auth=
npm_execpath=/Users/me/.nvm/versions/node/v8.0.0/lib/node_modules/npm/bin/npm-cli.js
npm_config_global_style=
npm_config_cache_lock_retries=10
npm_config_cafile=
npm_config_heading=npm
npm_config_searchlimit=20
npm_config_proprietary_attribs=true
npm_config_offline=
npm_config_fetch_retry_mintimeout=10000
npm_config_json=
npm_config_access=
npm_config_argv={"remain":[],"cooked":["test"],"original":["test"]}
npm_config_allow_same_version=
npm_config_https_proxy=
npm_config_engine_strict=
npm_config_description=true
npm_config_userconfig=/Users/me/.npmrc
npm_config_init_module=/Users/me/.npm-init.js
npm_package_author=
npm_config_user=1939786327
npm_config_node_version=8.0.0
npm_lifecycle_event=test
npm_config_save=true
npm_config_ignore_prepublish=
npm_config_editor=vi
npm_config_auth_type=legacy
npm_package_name=yarn-test
npm_config_tag=latest
npm_config_global=
npm_config_progress=
npm_config_searchstaleness=900
npm_config_optional=true
npm_config_ham_it_up=
npm_config_save_prod=
npm_config_force=
npm_config_bin_links=true
npm_config_searchopts=
npm_config_depth=Infinity
npm_package_main=index.js
npm_config_sso_poll_frequency=500
npm_config_rebuild_bundle=true
npm_package_version=1.0.0
npm_config_unicode=true
npm_config_fetch_retry_maxtimeout=60000
npm_package_scripts_test=env | grep npm_
npm_config_tag_version_prefix=v
npm_config_strict_ssl=true
npm_config_sso_type=oauth
npm_config_scripts_prepend_node_path=warn-only
npm_config_save_prefix=^
npm_config_loglevel=notice
npm_config_ca=
npm_config_save_exact=
npm_config_group=891112136
npm_config_fetch_retry_factor=10
npm_config_dev=
npm_config_version=
npm_config_prefer_offline=
npm_config_cache_lock_stale=60000
npm_config_cache_min=10
npm_config_searchexclude=
npm_config_cache=/Users/jvalore/.npm
npm_lifecycle_script=env | grep npm_
npm_config_color=true
npm_config_proxy=
npm_config_package_lock=true
npm_config_save_optional=
npm_config_ignore_scripts=
npm_config_user_agent=npm/5.0.3 node/v8.0.0 darwin x64
npm_config_cache_lock_wait=10000
npm_config_production=
npm_config_send_metrics=
npm_config_save_bundle=
npm_config_umask=0022
npm_config_init_version=1.0.0
npm_config_init_author_name=
npm_config_git=git
npm_config_scope=
npm_config_unsafe_perm=true
npm_config_tmp=/var/folders/yf/gcmnw1y96k31lh9ttjhfm8v9ssxkkq/T
npm_config_onload_script=
npm_node_execpath=/Users/me/.nvm/versions/node/v8.0.0/bin/node
npm_config_prefix=/Users/me/.nvm/versions/node/v8.0.0
npm_config_link=

Wow, that's a lot of stuff...