Add env subcommand

qmk_cli/subcommands/__init__.py

@@ -3,4 +3,5 @@
 We list each subcommand here explicitly because all the reliable ways of searching for modules are slow and delay startup.
 """
 from . import clone  # noqa
+from . import env  # noqa
 from . import setup  # noqa

qmk_cli/subcommands/env.py

@@ -0,0 +1,21 @@
+"""Prints environment information.
+"""
+import os
+
+from milc import cli
+
+
+@cli.argument('var', default=None, nargs='?', help='Optional variable to query')
+@cli.subcommand('Prints environment information.')
+def env(cli):
+    data = {
+        'QMK_HOME' : os.environ.get('QMK_HOME', "")
+    }
+
+    if cli.args.var:
+        # dump out requested arg
+        print(data[cli.args.var])
+    else:
+        # dump out everything
+        for key,val in data.items():
+            print(f'{key}="{val}"')