Each of these functions creates and executes a new process, passing an array of pointers to command-line arguments and using the PATH environment variable to find the file to execute.
These functions validate their parameters. If either cmdname or argv is a null pointer, or if argv points to null pointer, or argv[0] is an empty string, the invalid parameter handler is invoked, as described in Parameter Validation . If execution is allowed to continue, these functions set errno to EINVAL, and return -1. No new process is spawned.