C Program to Demonstrate fork() and pipe()
fork() is used to create a child process. This child process is a copy of the original(parent) process. It is the primary method of process creation on Unix-like operating systems.( See this article for reference).
fork(); // It does not take any parameter, it returns // integer values. It may return negative, // positive or zero integer values.
pipe(): It is used for inter-process communication in Linux. It is a system function. (See this article for reference)
int pipe(int pipefd);
C program to demonstrate fork() and pipe():
Write Linux C program to create two processes P1 and P2. P1 takes a string and passes it to P2. P2 concatenates the received string with another string without using string function and sends it back to P1 for printing.
Other string is: forgeeks.org Input : www.geeks Output : www.geeksforgeeks.org Input : www.practice.geeks Output : practice.geeksforgeeks.org
- To create child process we use fork(). fork() returns :
- <0 fail to create child (new) process
- =0 for child process
- >0 i.e process ID of the child process to the parent process. When >0 parent process will execute.
- pipe() is used for passing information from one process to another. pipe() is unidirectional therefore, for two-way communication between processes, two pipes can be set up, one for each direction.
int fd; pipe(fd); fd; //-> for using read end fd; //-> for using write end
Inside Parent Process : We firstly close the reading end of first pipe (fd1) then write the string though writing end of the pipe (fd1). Now parent will wait until child process is finished. After the child process, parent will close the writing end of second pipe(fd2) and read the string through reading end of pipe (fd2).
Inside Child Process : Child reads the first string sent by parent process by closing the writing end of pipe (fd1) and after reading concatenate both string and passes the string to parent process via fd2 pipe and will exit.
Concatenated string www.geeksforgeeks.org
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