FIFO for inter-process communication between Linux

The previous blog has introduced a way of inter-process communication, but it is only the needle for the process of blood relationship , that is, the communication between the father and son process, that for no blood relationship process, how to communicate it?
This will create a well-known pipeline to resolve the unrelated process communication, FIFO:

[Email protected]:~$ mkfifo xwp[email protected]:~$ ls-l myfifo prw10 Feb   6   Myfifo

Mkfifo has both commands and functions.

#include <sys/types.h><sys/stat.h>int mkfifo (constchar *pathname, mode_t mode);

1 /*fifo_write.c*/2#include <stdio.h>3#include <unistd.h>4#include <stdlib.h>5#include <sys/types.h>6#include <string.h>7#include <fcntl.h>8#include <sys/stat.h>9 Ten voidSys_err (Char*STR,intExitno) One { A perror (str); - exit (EXITNO); - } the  - intMainintargcChar*argv[]) - { -     intFD, Len; +     Charbuf[1024x768] ="Hello world\n"; -     if(ARGC <2) +     { Aprintf"./app myfifo\n"); atExit1); -     } -  -FD = open (argv[1],o_wronly); -     if(FD <0) -Sys_err ("Open",1); in  - Write (FD, buf, strlen (BUF)); to Close (FD); +  -     return 0; the } *  $ Panax Notoginseng  -  the /*Fifo_read*/ +#include <stdio.h> A#include <unistd.h> the#include <stdlib.h> +#include <sys/types.h> -#include <fcntl.h> $#include <sys/stat.h> $#include <string.h> -  - voidSys_err (Char*STR,intExitno) the { - perror (str);Wuyi exit (EXITNO); the } -  Wu intMainintargcChar*argv[]) - { About     intFD, Len; $     Charbuf[1024x768] = {0}; -     if(ARGC <2) -     { -printf"./app myfifo\n"); AExit1); +     } the  -FD = open (argv[1],o_rdonly); $     if(FD <0) theSys_err ("Open",1); the  theRead (FD, BUF,sizeof(BUF)); the Write (Stdout_fileno, buf, strlen (BUF)); - Close (FD); in  the     return 0; the } About  the  the Operation Method: the compiled into executable program separately: Fifo_write and Fifo_read +Enter under a terminal.Fifo_write Myfifo -Enter it under the other terminal.Fifo_read Myfifo theYou can observe the results

Note:

• When a FIFO pipeline is opened with write-only, the FIFO is not opened, and open write is blocked .
• The FIFO kernel is implemented to support two-way communication . (Pipe unidirectional communication because the parent-child process shares the same file structure body)
• FIFO can be one read end, multiple write end, also can one write end, multiple read end.

In fact, the FIFO point is still in the kernel buffer, but he points to all the kernel buffer, so he is not blocking, unlike pipe just pointing at both ends, causing blocking phenomenon

FIFO for inter-process communication between Linux