Exit Codes

An exit code is a small integer that a program returns to the operating system when it finishes, indicating whether it succeeded or failed, and if it failed, sometimes why. By convention, an exit code of 0 means success and any nonzero value indicates an error, with EXIT_SUCCESS and EXIT_FAILURE from <stdlib.h> providing portable constants for these. Exit codes are commonly checked by shell scripts and other programs that call a C program and need to know whether it completed successfully.