| [EINVAL] |
| | The requested process group ID is not legal. |
| [ESRCH] |
| | The requested process does not exist. |
| [ESRCH] |
| | The target process is not the calling process or a child of the calling process. |
| [EACCES] |
| | The requested process is a child of the calling process, but it has performed an exec(3) operation. |
| [EPERM] |
| | The target process is a session leader. |
| [EPERM] |
| | The requested process group ID is not in the session of the caller, and it is not equal to the process ID of the target process. |
|