>>> BUNDLE_VAR_b=def $CLI bundle validate -o json
"abc def"

>>> errcode $CLI bundle validate
Error: no value assigned to required variable b. Assignment can be done using "--var", by setting the BUNDLE_VAR_b environment variable, or in .databricks/bundle/<target>/variable-overrides.json file

Name: ${var.a} ${var.b}
Target: default
Workspace:
  User: $USERNAME
  Path: /Workspace/Users/$USERNAME/.bundle/${var.a} ${var.b}/default

Found 1 error

Exit code: 1