fds dispatch

); } //Open redirect File if(FD = open (argv[1], o_wronly| O_creat| O_trunc, s_irusr| S_IWUSR)) = =-1) {fprintf (stderr,"Open%s error:%s\n\a", argv[1], strerror (errno)); Exit (Exit_failure); } if(Dup2 (FD, Fileno (stdout)) = =-1) {fprintf (stderr,"Redirect Standard out error:%s\n\a", Strerror (errno)); \a is a bell character, a drop of exit (Exit_failure) will appear; } fprintf (stderr,"Now , please input string"); fprintf (stderr,"(to quit use ctrl+d\n)"); while(1) {fgets (buff

IntroductionLet's look at the following two semaphores: Sigpipe when the pipe reads off and then writes to the pipe, the sigpipe signal is emitted.SIGCHLD Child process exit will send a SIGCHLD signal to the parent process, the system default processing is to ignore the signalCode/************************************************************************* > File name:my_fork.c > Author: Krischou > Mail:[email protected] > Created Time:mon-10:42:26 AM CST *************************** ***************

The visitor pattern is the behavior pattern of the object. The purpose of the visitor pattern is to encapsulate some operations that are applied to a data structure element. Once these operations need to be modified, the data structure that accepts the operation can remain intact.Concept of the assignment　　The type of the variable being declared is called the static type of the variable, and some people call the static type the explicit type (apparent type), whereas the real type of the object r

)The function returns the total number of Operation file descriptors corresponding to the response operation, and the three groups of data are modified at the appropriate position. Only some of the response operations are not modified. Then we should use the fd_isset macro to find the returned file descriptor group. Here is a simple example of testing the readability of a single file descriptor: Int isready (int fd){Int RC;Fd_set FDS;Struct timeval TV

clear the specified fd_set, then call the macro fd_set to add the FD to be tested to fd_set, and then call the select function to test all FD in fd_set, finally, use the macro fd_isset to check whether the corresponding bit is still 1 after a FD is called by the Select function. The following is an example of testing the readability of descriptive words in a single file:Int isready (int fd){Int RC;Fd_set FDS;Struct Tim TV;Fd_zero (

a single file: Int isready (int fd) { Int RC; Fd_set FDS; Struct Tim TV; Fd_zero ( FDs ); Fd_set (FD, FDs ); TV. TV _sec = TV. TV _usec = 0; Rc = select (FD + 1, FDS, null, null, TV ); If (RC Return-1; Return fd_isset (FD, FDs )? 1: 0; } The following is a complex appl

Problem: Using Python to match strings between two strings in a regular wayWorkaround: Using the FindAll of the RE module, note that Re.match is only matched from the beginningMethod:Import''= Re.findall (R'', html_str)print(local[0]) #' var, FDS, FDS, FDs FDS, FDS

About main Dispatch queue and global Dispatch queue.The previous article said the way to create a Dispatch queue, in fact, without the dispatch_queue_create function can also get Dispatch queue, which is the main Dispatch queue and Global

Welcome into the coding world of summer.Today's shared knowledge of GCD, GCD's note: What developers need to do is define the tasks they want to perform and go home to the appropriate dispatch queue.There are two types of dispatch the Queue see the following table Types of Dispatch queue Description Serial

Record the usage of several important APIs for GCD.Dispatch_queue_create*stringis** * * * * * The newly created Dispatch queue.dispatch_queue_tdispatch_queue_create (constchar *label, Dispatch_queue_ attr_t attr);Used to create the dispatch Queue, the return value type is dispatch_queue_t, this method needs to pass two parameters, label is a string tag attached to the queue, this parameter is optional, and

as the data is ready in the horizontal trigger.[Plain]View Plaincopy [Email protected]:~/station$./t_select Ni hao ma, wo hen hao A, ni ne??? Ni hao Ma , Wo Hen Hao A, ni Ne??? ^c [CPP]View Plaincopy /************************************************************************* > File name:demo_sigio.c > Author:liuxingen > Mail: [email protected] > Created time:2014 August 14 Thursday 21:32 03 seconds *****************************************

Prior to doing a few years of Windows C + + development, Linux under the experience is not rich, causing me to look at the QEMU code, some places also need to go back to learn the Linux operating system implementation mechanism to more accurate understanding. Learning the Linux operating system in general to read a lot of books, it seems to understand, but to understand deeply, with this mediocre IQ I think it is more to see Code multi-code code. Gossip less, look at a function in the os-posix.c

look at the functions one by one.? 0102030405060708091011 int kbhit(){struct timeval tv;fd_set fds;tv.tv_sec = 0;tv.tv_usec = 0;FD_ZERO(fds);FD_SET(STDIN_FILENO, fds); //STDIN_FILENO is 0select(STDIN_FILENO+1, fds, NULL, NULL, tv);return FD_ISSET(STDIN_FILENO, fds