C++系统相关操作1 - 调用命令行并获取返回值
1. 关键词
关键词：
C++ 系统调用 system popen 跨平台
应用场景：
希望直接调用操作系统的某些命令，并获取命令的返回值。
2. sysutil.h
#pragma once
#include <cstdint>
#include <string>
namespace cutl
{
/**
* @brief Execute a system command.
*
* @param cmd the command to be executed.
* @return true if the command is executed successfully, false otherwise.
*/
bool system(const std::string &cmd);
/**
* @brief Execute a system command and get the output.
*
* @param cmd the command to be executed.
* @param result the output of the command.
* @return true if the command is executed successfully, false otherwise.
*/
bool callcmd(const std::string &cmd, std::string &result);
} // namespace cutl
不需要返回值时，可以直接使用system， 需要获取返回值时，可以调用callcmd。
3. sysutil.cpp
#include <map>
#include <iostream>
#include <strutil.h>
#include <cstdlib>
#include "sysutil.h"
#include "inner/logger.h"
#include "inner/system_util.h"
#include "inner/filesystem.h"
namespace cutl
{
bool system(const std::string &cmd)
{
return call_system(cmd);
}
bool callcmd(const std::string &cmd, std::string &result)
{
// 读取命令执行结果的最大Buffer长度
constexpr int MAX_CMD_BUF_LEN = 1024;
FILE *fp = pipline_open(cmd);
if (fp == NULL)
{
CUTL_ERROR("pipline_open error for cmd:" + cmd);
return false;
}
// 读取命令执行结果
char buffer[MAX_CMD_BUF_LEN] = {0};
char *res = fgets(buffer, sizeof(buffer), fp);
if (res == NULL)
{
CUTL_ERROR("read result error for cmd:" + cmd);
if (pipline_close(fp) != 0)
{
CUTL_ERROR("pipline_close error for cmd:" + cmd);
}
return false;
}
if (pipline_close(fp) != 0)
{
CUTL_ERROR("pipline_close error for cmd:" + cmd);
}
result = strip(std::string(buffer));
return true;
}
} // namespace cutl
3.1. system_util_unix.cpp
#if defined(_WIN32) || defined(__WIN32__)
// do nothing
#else
#include "system_util.h"
#include "inner/logger.h"
namespace cutl
{
bool call_system(const std::string &cmd)
{
if (cmd.empty())
{
CUTL_ERROR("cmd is empty!");
return false;
}
pid_t status;
status = std::system(cmd.c_str());
if (-1 == status)
{
CUTL_ERROR("system error!");
return false;
}
if (!WIFEXITED(status))
{
CUTL_ERROR("exit status:" + std::to_string(WEXITSTATUS(status)));
return false;
}
if (0 != WEXITSTATUS(status))
{
CUTL_ERROR("run shell script fail, script exit code:" + std::to_string(WEXITSTATUS(status)));
return false;
}
return true;
}
FILE *pipline_open(const std::string &cmd)
{
return popen(cmd.c_str(), "r");
}
int pipline_close(FILE *stream)
{
return pclose(stream);
}
} // namespace cutl
#endif // defined(_WIN32) || defined(__WIN32__)
3.2. system_util_win.cpp
#if defined(_WIN32) || defined(__WIN32__)
#include <cstdlib>
#include "system_util.h"
#include "inner/logger.h"
namespace cutl
{
// https://learn.microsoft.com/zh-cn/cpp/c-runtime-library/reference/system-wsystem?view=msvc-170
bool call_system(const std::string &cmd)
{
if (cmd.empty())
{
CUTL_ERROR("cmd is empty!");
return false;
}
int ret = system(cmd.c_str());
if (ret != 0)
{
CUTL_ERROR(std::string("system failure, error") + strerror(errno));
return false;
}
return true;
}
// https://learn.microsoft.com/zh-cn/cpp/c-runtime-library/reference/popen-wpopen?view=msvc-170
FILE *pipline_open(const std::string &cmd)
{
return _popen(cmd.c_str(), "r");
}
// https://learn.microsoft.com/zh-cn/cpp/c-runtime-library/reference/pclose?view=msvc-170
int pipline_close(FILE *stream)
{
return _pclose(stream);
}
} // namespace cutl
#endif // defined(_WIN32) || defined(__WIN32__)
4. 测试代码
#include "common.hpp"
#include "sysutil.h"
void TestSystemCall()
{
PrintSubTitle("TestSystemCall");
bool ret = cutl::system("echo hello");
std::cout << "system call 'echo hello', return: " << ret << std::endl;
auto cmd = "cmake --version";
std::string result_text;
ret = cutl::callcmd(cmd, result_text);
std::cout << "callcmd " << cmd << ", return: " << ret << std::endl;
std::cout << "callcmd " << cmd << ", result text: " << result_text << std::endl;
}
5. 运行结果
-------------------------------------------TestSystemCall-------------------------------------------
hello
system call 'echo hello', return: 1
callcmd cmake --version, return: 1
callcmd cmake --version, result text: cmake version 3.28.3
6. 源码地址
更多详细代码，请查看本人写的C++ 通用工具库: common_util, 本项目已开源，代码简洁，且有详细的文档和Demo。
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