POSIX kill
documenta a conotação "pesquisa":
[ESRCH]
No process or process group can be found corresponding to that specified by pid.
A edição anterior (2004) apresentou mais informações sobre a lógica:
Some implementations provide semantic extensions to the kill() function when the absolute value of pid is greater than some maximum, or otherwise special, value. Negative values are a flag to kill(). Since most implementations return [ESRCH] in this case, this behavior is not included in this volume of IEEE Std 1003.1-2001, although a conforming implementation could provide such an extension.