std::system - C / C++ 执行命令行

╰半橙微兮° 2022-11-05 08:50 148阅读 0赞

# **std::system** #

Defined in header `<cstdlib>`

int system(const char* command);

Execute system command - 执行系统命令

Invokes the command processor to execute a `command`.  
调用命令处理器执行 `command`。

Calls the host environment’s command processor (e.g. `/bin/sh`, `cmd.exe`, `command.com`) with the parameter command. Returns an implementation-defined value (usually the value that the invoked program returns).  
以参数 command 调用运行环境的命令处理器 (例如 `/bin/sh`, `cmd.exe`, `command.com`)。返回相应实现的定义值 (通常是被调用程序所返回的值)。

If `command` is a `null pointer`, checks if the host environment has a command processor and returns a nonzero value if and only if the command processor exists.  
若 `command` 为空，则检查运行环境是否有命令处理器，并当且仅当命令行存在才返回非零。

If `command` is a null pointer, the function only checks whether a `command processor` is available through this function, without invoking any command.  
如果 `command` 是空指针，则该函数仅通过该函数检查 `command processor` 是否可用，而不调用任何命令。

The effects of invoking a command depend on the system and library implementation, and may cause a program to behave in a non-standard manner or to terminate.  
调用命令的效果取决于系统和库的实现，并且可能导致程序以非标准方式运行或终止。

## 1. Parameters ##

`command`  
character string identifying the command to be run in the command processor. If a null pointer is given, command processor is checked for existence.  
标识要运行于命令处理器的命令字符串。若给出空指针，则检查命令处理器的存在性。

`C-string` containing the system command to be executed.  
包含要执行的系统命令的 `C-string`。

Or, alternatively, a `null pointer`, to check for a command processor.  
或者，可以使用 `null pointer` 来检查命令处理器。

## 2. Return value ##

Implementation-defined value. If command is a null pointer, returns a nonzero value if and only if the command processor exists.  
实现定义值。若 command 为空指针，则当且仅当命令处理器存在才返回非零值。

Notes  
On POSIX systems, the return value can be decomposed using WEXITSTATUS and WSTOPSIG  
POSIX 系统上，可用 WEXITSTATUS 和 WSTOPSIG 分解返回值。

The related POSIX function popen makes the output generated by command available to the caller.  
相关的 POSIX 函数 popen 使调用方可获取到 command 生成的输出。

If `command` is a null pointer, the function returns a non-zero value in case a `command processor` is available and a zero value if it is not.  
如果 `command` 是空指针，则在命令处理器可用的情况下该函数将返回非零值，否则将返回零。

If `command` is not a null pointer, the value returned depends on the system and library implementations, but it is generally expected to be the status code returned by the called command, if supported.  
如果 `command` 不是空指针，则返回的值取决于系统和库的实现，但通常应将其视为调用的命令返回的状态码 (如果支持)。

## 3. Example ##

/home/yongqiang/CLionProjects/hash_table/cmake-build-debug/hash_table
    ret = 0
    Hello, World!
    
    total 124
    -rw-r--r-- 1 yongqiang yongqiang 45597 Mar  4 23:12 CMakeCache.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  4 23:16 CMakeFiles
    -rw-r--r-- 1 yongqiang yongqiang  5124 Mar  4 23:12 Makefile
    -rw-r--r-- 1 yongqiang yongqiang  1549 Dec  1 00:43 cmake_install.cmake
    -rwxr-xr-x 1 yongqiang yongqiang 33760 Mar  4 23:16 hash_table
    -rw-r--r-- 1 yongqiang yongqiang  5799 Mar  4 23:12 hash_table.cbp
    -rw-r--r-- 1 yongqiang yongqiang     0 Mar  4 23:16 test.txt
    
    Process finished with exit code 0

## 4. Example ##

/home/yongqiang/CLionProjects/hash_table/cmake-build-debug/hash_table
    Checking if processor is available...Ok
    
    Executing command DIR...
    CMakeCache.txt	Makefile	     hash_table      test.txt
    CMakeFiles	cmake_install.cmake  hash_table.cbp
    
    The value returned was: 0.
    
    Process finished with exit code 0

## 5. `mkdir` \- `rm` \- `mv` ##

//============================================================================
    // Name        : Yongqiang Cheng
    // Author      : Yongqiang Cheng
    // Version     : Version 1.0.0
    // Copyright   : Copyright (c) 2020 Yongqiang Cheng
    // Description : Hello World in C++, Ansi-style
    //============================================================================
    
    #ifndef _CRT_SECURE_NO_WARNINGS
    #define _CRT_SECURE_NO_WARNINGS
    #endif
    
    #include <cstdlib>
    #include <fstream>
    #include <iostream>
    
    const int len = 3 * 4;
    
    void system_command_mkdir(const std::string dir) {
        int ret = std::system(("mkdir -p " + dir).c_str());
    
        if (ret != 0) {
            std::cout << "The value returned was: " << ret << ".\n" << std::endl;
        }
    }
    
    void system_command_rm(const std::string dir) {
        int ret = std::system(("rm -rf " + dir).c_str());
    
        if (ret != 0) {
            std::cout << "The value returned was: " << ret << ".\n" << std::endl;
        }
    }
    
    void system_command_mv(const std::string src, const std::string dst) {
        int ret = std::system(("mv " + src + " " + dst).c_str());
    
        if (ret != 0) {
            std::cout << "The value returned was: " << ret << ".\n" << std::endl;
        }
    }
    
    int main() {
        int ret = std::system("ls -l");  // "ls -l"
        std::cout << "\nret = " << ret << std::endl << std::endl;
    
        std::string dir = "yongqiang";
        system_command_mkdir(dir);
    
        ret = std::system("ls -l");  // "ls -l"
        std::cout << "\nret = " << ret << std::endl << std::endl;
    
        system_command_rm(dir);
    
        ret = std::system("ls -l");  // "ls -l"
        std::cout << "\nret = " << ret << std::endl << std::endl;
    
        system_command_mkdir(dir);
    
        std::string dst_dir = "yongqiangcheng";
        system_command_mv(dir, dst_dir);
    
        ret = std::system("ls -l");  // "ls -l"
        std::cout << "\nret = " << ret << std::endl << std::endl;
    
        std::cout << "Hello, World!\n" << std::endl;
    
        return 0;
    }

/home/yongqiang/CLionProjects/hash_table/cmake-build-debug/hash_table
    total 164
    -rw-r--r-- 1 yongqiang yongqiang 45597 Mar  4 23:12 CMakeCache.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  5 22:45 CMakeFiles
    -rw-r--r-- 1 yongqiang yongqiang  5124 Mar  4 23:12 Makefile
    -rw-r--r-- 1 yongqiang yongqiang  1549 Dec  1 00:43 cmake_install.cmake
    -rwxr-xr-x 1 yongqiang yongqiang 74608 Mar  5 22:45 hash_table
    -rw-r--r-- 1 yongqiang yongqiang  5799 Mar  4 23:12 hash_table.cbp
    -rw-r--r-- 1 yongqiang yongqiang   464 Mar  4 23:16 test.txt
    
    ret = 0
    
    total 164
    -rw-r--r-- 1 yongqiang yongqiang 45597 Mar  4 23:12 CMakeCache.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  5 22:45 CMakeFiles
    -rw-r--r-- 1 yongqiang yongqiang  5124 Mar  4 23:12 Makefile
    -rw-r--r-- 1 yongqiang yongqiang  1549 Dec  1 00:43 cmake_install.cmake
    -rwxr-xr-x 1 yongqiang yongqiang 74608 Mar  5 22:45 hash_table
    -rw-r--r-- 1 yongqiang yongqiang  5799 Mar  4 23:12 hash_table.cbp
    -rw-r--r-- 1 yongqiang yongqiang   464 Mar  4 23:16 test.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  5 22:45 yongqiang
    
    ret = 0
    
    total 164
    -rw-r--r-- 1 yongqiang yongqiang 45597 Mar  4 23:12 CMakeCache.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  5 22:45 CMakeFiles
    -rw-r--r-- 1 yongqiang yongqiang  5124 Mar  4 23:12 Makefile
    -rw-r--r-- 1 yongqiang yongqiang  1549 Dec  1 00:43 cmake_install.cmake
    -rwxr-xr-x 1 yongqiang yongqiang 74608 Mar  5 22:45 hash_table
    -rw-r--r-- 1 yongqiang yongqiang  5799 Mar  4 23:12 hash_table.cbp
    -rw-r--r-- 1 yongqiang yongqiang   464 Mar  4 23:16 test.txt
    
    ret = 0
    
    total 164
    -rw-r--r-- 1 yongqiang yongqiang 45597 Mar  4 23:12 CMakeCache.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  5 22:45 CMakeFiles
    -rw-r--r-- 1 yongqiang yongqiang  5124 Mar  4 23:12 Makefile
    -rw-r--r-- 1 yongqiang yongqiang  1549 Dec  1 00:43 cmake_install.cmake
    -rwxr-xr-x 1 yongqiang yongqiang 74608 Mar  5 22:45 hash_table
    -rw-r--r-- 1 yongqiang yongqiang  5799 Mar  4 23:12 hash_table.cbp
    -rw-r--r-- 1 yongqiang yongqiang   464 Mar  4 23:16 test.txt
    drwxr-xr-x 1 yongqiang yongqiang   512 Mar  5 22:45 yongqiangcheng
    
    ret = 0
    
    Hello, World!
    
    
    Process finished with exit code 0

## References ##

[https://en.cppreference.com/w/cpp/utility/program/system][https_en.cppreference.com_w_cpp_utility_program_system]  
[http://www.cplusplus.com/reference/cstdlib/system/][http_www.cplusplus.com_reference_cstdlib_system]

[https_en.cppreference.com_w_cpp_utility_program_system]: https://en.cppreference.com/w/cpp/utility/program/system
[http_www.cplusplus.com_reference_cstdlib_system]: http://www.cplusplus.com/reference/cstdlib/system/