Hi, This question is provided by one of my friends. He only provided me little information. I didn't know much detail in this part. I have searched the relative information on the network. But with no good result. So I asked for help in mailing list. 2016-02-18 0:22 GMT+08:00 Greg KH <greg@xxxxxxxxx>: > On Wed, Feb 17, 2016 at 03:52:45PM +0800, 慕冬亮 wrote: >> Hi everyone, >> Unix systems support a large number of special characters that >> receive special processing by the OS. One such character is the >> “suspend” character (ctrl-Z by default), that causes a SIGTSTP signal >> to be sent to the application process. The default action for the >> signal is to suspend execution of the process. The system responds to >> the suspend character (by sending the signal) as soon as possible >> after it is typed in. In older Unix systems there was another special >> character known as the “delayed suspend” character (ctrl-Y by default) >> that had the same effect as the suspend character, except that the >> signal is sent when the application process consumes the character, >> rather than right away. (That this feature is no longer supported is >> perhaps some indication of how useful it was ...) The suspend and the >> delayed-suspend characters have the effect, when they are processed, >> of deleting all characters currently waiting to be read by the user >> application that arrived before them. Explain, how both special >> characters are implemented? > > That sounds like a homework question, why exactly do you need/want to > know this, and what have you done already to try to figure it out > yourself? > > greg k-h -- My best regards to you. No System Is Safe! mudongliang _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies