Errors validating a document (which happens to be a schema) against the core meta schema

[paulprogrammer]

I'm struggling to validate a schema I'm developing against the core meta-schema using ajv-cli 5.0.0 (according to the package.json -- I guess there's no version identifier in the cli see #198 )

Imagine I've got a really basic schema named foo-schema.json:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "description": "a foo schema",
  "type": "object",
  "properties": {
    "bar": {
      "type": "string"
    },
  "additionalProperties": false
  }
}

and I wish to ensure this is a valid schema according to the $schema reference (in this case, the core meta schema).

Initially I was hoping I could just issue an ajv validate -d ... and it'd figure out what schema I was trying to use (after all, I put a $schema reference in the doc):

> ajv validate -d foo-schema.json
error: parameter -s is required

Therefore, I issue the following command where schema.json is harvested from the url http://json-schema.org/draft-07/schema

> ajv validate -s schema.json -d foo-schema.json
schema schema.json is invalid
error: schema with key or id "http://json-schema.org/draft-07/schema" already exists

So to fix that, I'm removing the $schema and $id elements from the downloaded schema.json. Now I get:

> ajv validate -s schema.json -d foo-schema.json
strict mode: use allowUnionTypes to allow union type keyword at "#" (strictTypes)
schema schema.json is invalid
error: unknown format "uri-reference" ignored in schema at path "#/properties/%24id"

Well, I'm kinda stumped now. Is there a canonical way to validate that a schema is correct according to the meta-schema?