How to call the system() function in Linux

How to call the system() function in Linux system

In the Linux system, the system() function is one of the very important system call functions, which can be used to execute command line commands. This article will introduce how to call the system() function in Linux systems and provide specific code examples. Let’s find out.

The prototype of the system() function is as follows:

int system(const char *command);

The parameter of this function is a pointer to a string constant, which is the command line command to be executed.

Before calling the system() function, we need to include the header file <stdlib.h></stdlib.h>.

The following is a sample code that shows how to call the system() function to execute a simple command:

#include <stdio.h>
#include <stdlib.h>

int main() {
    int return_value;

    return_value = system("ls -l");

    if (return_value == -1) {
        printf("调用system()函数失败。
");
        exit(EXIT_FAILURE);
    }

    printf("system()函数返回值：%d
", return_value);

    return 0;
}

In this sample code, we call the system() function to executels -lCommand, this command is used to list detailed information of files and folders in the current directory.

After calling the system() function, we can determine whether an error has occurred by checking its return value. If the return value is -1, the call failed; otherwise, the return value represents the exit status code of the called command.

It should be noted that the return value of the system() function is not always used to check errors. Sometimes it can also be used to further process the command execution results.

In addition, you can also make the system() function print the output of the command after executing the command by adding "echo " before the command string, as shown below:

#include <stdio.h>
#include <stdlib.h>

int main() {
    int return_value;

    return_value = system("echo 'Hello, World!'");

    if (return_value == -1) {
        printf("调用system()函数失败。
");
        exit(EXIT_FAILURE);
    }

    printf("system()函数返回值：%d
", return_value);

    return 0;
}

In this example, we call the system() function to execute the echo 'Hello, World!' command, which is used to print the string "Hello, World!".

To summarize, in Linux systems, command line commands can be easily executed by calling the system() function. Developers can use different command strings according to specific needs, and use the return value to determine whether the call is successful and further process the command execution results.

We hope that the code examples provided in this article can help developers better understand how to call the system() function in Linux systems. In practical applications, attention needs to be paid to ensuring the security of command strings to avoid potential security risks.

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