The inherent reason is that -1 is the most common error return code in C based APIs. The problem is not naively handling an error case, it's not handling an err

The inherent reason is that -1 is the most common error return code in C based APIs. The problem is not naively handling an error case, it's not handling an error case. Using a different value might avoid calling killall -1, but the program would still be incorrect. This is the same sort of argument as strlcat vs strncat, and people can't agree on that one.