Detailed explanation of the linux system call system() function

Linux system call system() function detailed explanation
System call is a very important part of the Linux operating system. It provides a way to interact with the system kernel. Among them, the system() function is one of the commonly used system call functions. This article will introduce the use of the system() function in detail and provide corresponding code examples.

Basic concepts of system calls
System calls are a way for user programs to interact with the operating system kernel. User programs request the operating system kernel to complete certain tasks by calling system call functions. System call functions provide a set of interfaces for user programs to call. These interfaces allow user programs to obtain higher-level permissions and perform certain operations that only the operating system kernel can perform.

Introduction to the system() function
The system() function is a standard library function in the C language and is used to call the system shell command in the Linux system. Its prototype is:

int system(const char *command);

Among them, the command parameter is a shell command string separated by spaces. When the function is executed successfully, it returns 0, and when it fails, it returns a specific error code.

Execution steps of system() function
When the system() function is called, it will create a child process, and then call the /bin/sh command in the child process to execute the specified shell command. The parent process will wait for the exit of the child process and return the exit status of the child process.

How to use the system() function
When using the system() function, you need to pay attention to the following points:

1. Before calling the system() function, The corresponding header file needs to be included:

   #include <stdlib.h>

2. Pass the shell command to be executed as a string to the system() function, for example:

   system("ls -l");

   The above code will execute "ls -l" command and output the file list in the terminal.

3. The result of the command execution can be judged by the return value of the system() function. For example:

   int status = system("ls -l");
   if (status == 0) {
    printf("Command executed successfully.
   ");
   } else {
    printf("Command failed.
   ");
   }

   The above code will output the corresponding response based on the return value of the system() function. result.

Code example of system() function
The following is a simple code example that demonstrates how to use the system() function to execute a shell command:

#include 
#include <stdlib.h>

int main() {
    int status = system("echo 'Hello, world!'");
    if (status == 0) {
        printf("Command executed successfully.
");
    } else {
        printf("Command failed.
");
    }
    return 0;
}

The above code will execute the "echo 'Hello, world!'" command and output the corresponding results.

Summary
The system() function is one of the commonly used system call functions in Linux systems. It can be used to execute shell commands and determine the result of command execution through the return value. Understanding the use of the system() function is very important for developing Linux applications and can help us better utilize the functions provided by the operating system. I hope this article can help readers better understand the role and usage of the system() function.

The above is the detailed content of Detailed explanation of the linux system call system() function. For more information, please follow other related articles on the PHP Chinese website!