Exit code
A small integer a process returns on exit to indicate success (usually 0) or failure (non-zero) to whatever started or supervises it.
Definition
An exit code is a small integer a process reports when it terminates. By convention:
0means success- non-zero means failure (or a specific failure category)
Exit codes are how a process communicates “how it ended” to the thing supervising it (shell, service manager, container runtime, orchestrator).
Why exit codes matter
Exit codes influence automation:
- whether a process is restarted
- whether a deploy is considered successful
- whether monitoring marks an instance as unhealthy
They’re a simple interface, but they’re often the first clue in an incident.