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How to spawn a process in C?

In the world of programming, spawning a process refers to creating a new instance of a program or application. This can be a useful techniqu...

In the world of programming, spawning a process refers to creating a new instance of a program or application. This can be a useful technique when developing complex software that requires multiple processes to run simultaneously. In this article, we will explore the steps to spawn a process in the C programming language.

Before we dive into the technical details, it is important to understand the concept of processes. In simple terms, a process is an executing instance of a program. Every program, no matter how small, is considered a process when it is running. Each process has its own memory space, execution state, and system resources. These processes can communicate with each other and share data, making them essential for multitasking and multi-user systems.

Now, let's see how we can spawn a process in C. The first step is to include the "stdlib.h" header file in our code. This file contains the "system()" function, which we will use to spawn a new process. This function takes a string as an argument, which will be the command we want to execute in the new process.

Next, we need to create a new process using the "fork()" system call. This call creates a copy of the current process, known as the child process. The new process will have the same code, data, and heap space as the parent process. However, it will have a separate execution stack and unique process ID. The "fork()" call returns a value of 0 to the child process and the process ID of the child to the parent process.

In the child process, we need to use the "execl()" function to replace the child process's memory space with the new program we want to execute. This function takes the program's name, command-line arguments, and environment variables as arguments. If the execution is successful, the child process will be replaced by the new program, and the parent process will continue to run its code.

Let's look at an example to better understand the process spawning in C. Suppose we want to execute the "ls" command in a new process. Our code will look something like this:

#include <stdlib.h>

#include <stdio.h>

#include <unistd.h>

int main() {

int pid = fork(); //Creates a new process

if (pid == 0) { //Child process

execl("/bin/ls", "ls", "-l", NULL); //Execute ls command


else { //Parent process

printf("Parent process is running\n");


return 0;


In the above code, the "fork()" call creates a child process, and the "execl()" function replaces it with the "ls" command. The "printf()" statement will only be executed by the parent process.

It is worth mentioning that spawning a process is not limited to executing external commands. We can also spawn a new process and run a different program within the same code. This technique is commonly used in client-server applications, where the server spawns a new process to handle each client's request.

In conclusion, spawning a process in C involves using system calls and functions to create a new instance of a program. This technique is essential for developing complex software that requires multitasking and multi-user capabilities. By following the steps mentioned in this article, you can easily spawn a process in your C programs. Happy coding!

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