Inter-process Pipeline communication

Communication between parent and child processes through pipelines.

Pipelines can only be used between two processes with a common ancestor, typically one pipeline is created by another, and after the process calls fork, the pipeline can be used between the parent and child processes.

The general process, fd[0] means reading, fd[1] means writing.

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If it is useful to the pipe, it is written into the pipe and read from the pipe.

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Between the parent and child processes.

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Therefore, through the simple read, write function, the target file is set to Fd[0] fd[1] that can complete the communication between the parent-child process.

write usage, read similar.
int write (int handle, void *buf, int nbyte);
Handle isFile descriptor;
BUF is the specified buffer, which is thePointer, pointing to a section of the internal deposit cells;
Nbyte is to writeFileThe specified number of bytes; return value: Number of bytes written to the document (success); 1 (Error)
The Write function writes BUF nbyte to the document referred to in the file descriptor handle, returns the number of bytes written when successful, and returns -1 on error.

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#define BUFSZ 256

int main (void)

{

int fd[2];

Char Buf[bufsz];

pid_t pid;

int Len;

if (pipe (FD) <0)

{

Perror ("Failed to pipe");

Exit (1);

}

if ((PID = fork ()) <0)

{

Perror ("Failed to fork");

Exit (1);

}

else if (PID > 0)

{

printf ("father wrote password to pipe\n");

Write (fd[1], "1234\n", 25); The parent process writes the password into sleep, waiting for the child process to read.

Sleep (1);

Read (Fd[0], buf, BUFSZ);

printf ("Father read result is%s\n", buf);

Exit (0);

}

Else

{

printf ("Child would read from pipe\n");

Read (Fd[0], buf, BUFSZ); The child process reads the password from the pipeline that the parent process writes into

printf ("Child read result is%s\n", buf);

printf ("Child wrote password to pipe\n");

Write (fd[1], "4321\n", 25); The child process writes its own password, waiting for the parent process to read

}

return 0;

}

The results of the operation are as follows:

[Email protected] xcui]#./pipe

Father wrote password to pipe

Child would read from pipe

Child read result is 1234

Child wrote password to pipe

Father Read result is 4321

Inter-process Pipeline communication