Semantic Exit Codes

Usage

Go

os.Exit(exit.Forbidden) // The user isn't permitted to perform this action
os.Exit(exit.Unavailable) // An API this program consumes isn't available

Rust

use semantic_exit::{exit, Code};

exit(Code::Forbidden);
exit(Code::Unavailable);

Python

import exit

exit.Code.Forbidden.exit()
exit.Code.Unavailable.exit()

See the complete list of exit codes.

About

Conventionally, exiting a program with zero indicates success while nonzero indicates failure.

os.Exit(0) // success
os.Exit(1) // failure

But the system call exit accepts values between 0 and 255, leaving 254 different ways of expressing failure.

This library's goals are to define exit codes that are:

1. Broadly applicable to heterogenous Command Line tools
2. Easy to partition into user errors and system errors

It defines codes in two unreserved ranges: 80-99 for user errors and 100-119 for software or system errors.

The Codes

Exit Code	Name	Meaning
0	OK	The program exited successfully.
1	NotOK	The program exited unsuccessfully but gives no extra context as to what the failure was.
80	UsageError	The program exited unsuccessfully because it was was used incorrectly. (e.g. a required argument was omitted or an invalid value was supplied for a flag.)
81	UnknownSubcommand	The program exited unsuccessfully because an unrecognized subcommand was invoked. (Used by CLI multi-tools.)
82	RequirementNotMet	The program exited unsuccessfully because a prerequisite of it wasn't met.
83	Forbidden	The program exited unsuccessfully because the user isn't authorized to perform the requested action.
84	MovedPermanently	The program exited unsuccessfully because it has been migrated to a new location.
100	InternalError	The program exited unsuccessfully because of a problem in its own code. (Used instead of 1 when the problem is known to be with the program's code or dependencies.)
101	Unavailable	The program exited unsuccessfully because a service it depends on was not available. (e.g. A local daemon or remote service did not respond, a connection was closed unexpectedly, an HTTP service responded with 503.)

Reserved Codes and Prior Art

• Values above 128 are reserved for signals. (When a program is terminated with a signal, its exit code is 128 + the signal's numeric value. When you terminate a program with Ctrl C, for example, you send it the signal SIGINT — whose value is 2 — and the program exits with 130.)
• Bash reserves 2, 126, and 127.
• sysexits.h defines 64-78. The sysexits.h codes were originally defined for sendmail but have been used many places since. (Compare Semantic Exit Codes to sysexits.h codes)