Question

I am looking for a way to get the output of a command when it is run from within a C++ program. I have looked at using the system() function, but that will just execute a command. Here’s an example of what I’m looking for:

std::string result = system('./some_command'); 

I need to run an arbitrary command and get its output. I’ve looked at boost.org, but I have not found anything that will give me what I need.

Answer 1

#include <cstdio> #include <iostream> #include <memory> #include <stdexcept> #include <string> #include <array>  std::string exec(const char* cmd) {     std::array<char, 128> buffer;     std::string result;     std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);     if (!pipe) {         throw std::runtime_error("popen() failed!");     }     while (fgets(buffer.data(), static_cast<int>(buffer.size()), pipe.get()) != nullptr) {         result += buffer.data();     }     return result; } 

Pre-C++11 version:

#include <iostream> #include <stdexcept> #include <stdio.h> #include <string>  std::string exec(const char* cmd) {     char buffer[128];     std::string result = "";     FILE* pipe = popen(cmd, "r");     if (!pipe) throw std::runtime_error("popen() failed!");     try {         while (fgets(buffer, sizeof buffer, pipe) != NULL) {             result += buffer;         }     } catch (...) {         pclose(pipe);         throw;     }     pclose(pipe);     return result; } 

Replace popen and pclose with _popen and _pclose for Windows.