Running shell commands...?

jadedfs (4)
I can run a shell command with:
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    #include <iostream>
    #include <iostream>
    #include <stdio.h>
    #include <stdlib.h>

    using namespace std;
    string cmdinput;
    string GetStdoutFromCommand(string cmd) {

    string data;
    FILE * stream;
    const int max_buffer = 256;
    char buffer[max_buffer];
    cmd.append(" 2>&1");

    stream = popen(cmd.c_str(), "r");
    if (stream) {
    while (!feof(stream))
    if (fgets(buffer, max_buffer, stream) != NULL) data.append(buffer);
    pclose(stream);
    }
    return data;
    }

    int main (){
      string com = GetStdoutFromCommand("apt-get install");
      cout << "Command: " << com << endl;

    return 0;
    }

The program runs the entire shell command ("apt-get install") and prints output as it should:
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Command: E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?


However, when I replace ("apt-get install") with the string cmdinput (Declared on line 7) and revise the bottom section like so:
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    int main (){
      cin >> cmdinput;
      string com = GetStdoutFromCommand(cmdinput);
      cout << "Command: " << com << endl;

    return 0;
    }


This allows me to input the command of which will executed... Sadly, it doesn't work very well. In contrast to example one, which had "apt-get install" coded into the program, having the user input "apt-get install" as per example two doesn't bring the correct result- it brings up the display that appears when you input just "apt" into the terminal...

So replacing "apt-get install" in example one with a string only allows the program to execute the first word in the string- why...? How can I fix this? I've been racking my brain for quite a while and nothing's come out...


EDIT: It is now apparent to be that it takes every different word from input as a seperate command- how can I make it take each word as one command- I.E. "apt-get install" instead of "apt-get" "install"?
Last edited on
modoran (1988)
cin stops after first space. To fix it use getline:
http://www.cplusplus.com/reference/string/string/getline/

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

    using namespace std;
    string cmdinput;
    string GetStdoutFromCommand(string cmd) {

    string data;
    FILE * stream;
    const int max_buffer = 256;
    char buffer[max_buffer];
    cmd.append(" 2>&1");

    stream = popen(cmd.c_str(), "r");
    if (stream) {
    while (!feof(stream))
    if (fgets(buffer, max_buffer, stream) != NULL) data.append(buffer);
    pclose(stream);
    }
    return data;
    }

    int main (){
        cout << "Enter your command:" << endl;
        string cmdinput;
        getline (cin, cmdinput);
        cout << "Your command was '" << cmdinput << "'" << endl;
      string com = GetStdoutFromCommand(cmdinput);
      cout << "Command: " << com << endl;

    return 0;
    }
jadedfs (4)
Thank you!
I'm rather upset at myslef for not catching such a simple mistake...
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