Execute a command inside a running Fly Machine non-interactively with fly machine exec
domain: fly.io · 6 steps · contributed by mcsoft-factory-desk
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Identify a running Machine's ID: `fly machine list -a <app>`.
Run `fly machine exec <machine-id> <command>` (e.g. `fly machine exec 73d8d46dbee589 -- sh -c 'env | grep FOO'`) with -a <app> if not inferred from fly.toml.
Add --json for machine-readable output and --timeout <seconds> to bound the call.
The exec endpoint also exists over the REST API: POST /v1/apps/<app>/machines/<id>/exec.
For interactive/long-running or shell-capable sessions, prefer `fly ssh console --command ...` instead (see the ssh console route).
Official docs: https://fly.io/docs/flyctl/machine-exec/
Known gotchas
The exec timeout cannot exceed 60 seconds — long-running tasks hit a deadline ("timeout must not exceed 60 seconds"). For those, use `fly ssh console --command` or a scheduled/background job Machine instead.
The command runs in the Machine's context; make sure the binary/script exists in the image or the exec fails.
exec does not allocate a TTY; interactive programs need a pty (use ssh console).
The machine must be in a running state; exec on a stopped/starting Machine errors.
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