How to print system() output in C++?

Question

String cmd = "/alcatel/omc3/osm/script/proc_upd.pl -s stop -p MFSUSMCTRL -u" + userName;      
system(cmd);

I want to print the output of system() function. How can I do that ?

The `system` function only returns the exit code of the "program" you run, not the actual output to its standard output. Look into the `popen` function instead. — Some programmer dude, Aug 04 '16 at 12:36
@JoachimPileborg That's the right answer. Perhaps you could write it up? — Jonathan Mee, Aug 04 '16 at 13:01

TGrossb · Answer 1 · 2016-08-04T23:37:28.373

You can use the function popen. It will allow you to get the result of a command. You must add #include <stdio.h> to your code to use this. The basic syntax is FILE * file_name = popen("command", "r"). Your code might look something like:

#include <iostream>
#include <stdio.h>
using namespace std;

char buf[1000];
string userName;

int main() {

    cout << "What is your username?\nUsername:";

    //input userName
    cin >> userName;

    //declare string strCMD to be a command with the addition of userName
    string strCMD = "/alcatel/omc3/osm/script/proc_upd.pl -s stop -p MFSUSMCTRL -u" + userName;

    //convert strCMD to const char * cmd
    const char * cmd = strCMD.c_str();

    //execute the command cmd and store the output in a file named output
    FILE * output = popen(cmd, "r");

    while (fgets (buf, 1000, output)) {
        fprintf (stdout, "%s", buf);
    }
    pclose(output);
    return 0;
}

How to print system() output in C++?

1 Answers1