Implement a robust shell CLI

Implement a POSIX-compliant shell script invoked as ./script.sh <username> <path_of_file> that outputs a single line formatted as "<timestamp> <license> <user@hostname>". Requirements: parse and validate both positional arguments; compute an ISO 8601 UTC timestamp; derive the license string from the file (state and document your assumption, e.g., read a 'License:' header or first token); construct user@hostname using the provided username and the local hostname; handle missing file, permission errors, and non-ASCII paths; return meaningful exit codes; and outline basic tests (happy path, bad args, missing file).