Forgive me if I remove the tokens themselves from the snippets.
Validate token:
#!/bin/bash
curl -H 'Authorization: Bearer ${ACCESS}'\
-X GET 'https://id.twitch.tv/oauth2/validate'
Get test user:
#!/bin/bash
curl -H 'Client-ID: ${CLIENT_ID}'\
-H 'Authorization: Bearer ${ACCESS}'\
-X GET 'https://api.twitch.tv/helix/users?id=44322889'