STREAMS Programming Guide


The same as the M_SIG message, except for the priority. M_PCSIG is often preferable to M_SIG especially in TTY applications, because M_SIG may be queued while M_PCSIG is more likely to get through quickly. For example, if an M_SIG message is generated when the DEL (delete) key is pressed on the terminal and the user has already typed ahead, the M_SIG message becomes queued and the user doesn't get the call until it's too late; it becomes impossible to kill or interrupt a process by pressing a delete key.