Why an unattended script fails silently on macOS: TCC permissions for files, Accessibility and Automation

What it is

macOS mediates access to sensitive resources — a user's files outside an app's own container, keyboard/screen control (Accessibility), and sending Apple Events to control one app from another (Automation) — through the Transparency, Consent and Control (TCC) subsystem, independent of Unix file permissions. A process can be root and still be denied: TCC decisions are keyed to the signed identity of the requesting binary — Terminal, a script interpreter, sshd — not to the Unix user ID alone.

Why it matters

An agent running a script from Terminal, a scheduled launchd job, or an SSH session inherits whatever TCC grants belong to the specific binary actually making the request — often Terminal.app or sshd, not the script itself. A script that reads mail data, controls another app through osascript's tell application, or moves the mouse programmatically fails, usually silently or with an error that does not name which of the three categories (Full Disk Access, Automation, Accessibility) is missing, the first time it runs under a new binary. An unsigned or ad-hoc-signed tool is identified by its code hash, so every rebuild looks like a new program and loses its grants; a tool signed with a stable Developer ID keeps them across versions.

How to apply

• Grant Full Disk Access, Automation and Accessibility explicitly, once, under System Settings > Privacy & Security (Full Disk Access, Automation, Accessibility), to the actual binary performing the action — Terminal, the specific interpreter, or the agent's own binary — not to a wrapper that isn't the one making the call.
• On a fleet of managed Macs, grant the same categories with no local interaction by pushing a Privacy Preferences Policy Control configuration profile through MDM, naming the tool by its code-signing identifier.
• To let re-consent happen from scratch after a mistaken denial, reset one service for one app — tccutil reset Accessibility com.example.tool — or a whole category for every app by omitting the bundle identifier.
• Never attempt to edit the TCC database file directly; current macOS versions block direct writes to it even from an admin account, and doing so bypasses the consent record the OS relies on.

Pitfalls

• Testing a script's permissions from one Terminal window or IDE and assuming the grant carries over to cron, a LaunchDaemon, or a different terminal emulator — each requesting binary needs its own grant.
• Assuming sudo bypasses TCC; it does not, because the check is about the calling application's identity and consent record, not the Unix privilege level.
• Forgetting that tccutil reset revokes immediately; the next attempt shows the consent prompt again, or fails outright for a background process with no one to answer it.