Leak check: interprocess communication (IPC): Piping

Pipelines are the oldest form of IPC for UNIX systems, and all UNIX systems provide such communication mechanisms. The pipeline has the following two limitations:

(1) Historically, pipelines are half-duplex (i.e. data can only flow in one direction).

(2) Pipelines can only be used between two processes with a common ancestor. Typically, a pipeline is created with a process that can be used between parent and child processes after the process calls fork.

Pipeline creation:

The pipeline is created by calling the pipe function.

Header files: #include <unistd.h>

Prototype: int pipe (int fd[2])

Return value: Succeeded, returned 0, failed, returned-1.

Return two file descriptor via parameter FD: fd[0] Open for Read, fd[1] for write. The output of fd[1] is the input of fd[0].

The illustrations are as follows:

　　

Test procedure:

1#include <stdio.h>2#include <unistd.h>3#include <stdlib.h>4 5 intMainintargcChar*argv[])6 {7     intN;8     intfd[2];9 pid_t pid;Ten     Charbuf[ -] = {0}; One  A     if(Pipe (FD) <0) -     { -printf"Pipe error\n"); the         return-1; -     } -  -     if(PID = fork ()) <0) +     { -printf"Fork error\n"); +         return-1; A     } at     Else if(PID >0) -     { -Close (fd[0]); -printf"parent Process id:%d, child process id:%d\n", Getpid (), PID); -Write (fd[1],"Hello world\n",sizeof("Hello world\n")); -     } in     Else -     { toClose (fd[1]); +n = Read (fd[0],buf,sizeof(BUF)); -printf"Child process id:%d\n", Getpid ()); theWrite (Stdout_fileno,"Child process:",sizeof("Child process:")); * write (stdout_fileno,buf,n); $     }Panax Notoginseng  -     return 0; the  +}

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Leak check: interprocess communication (IPC): Piping