macOS Coding using system commands

[jmac555]

As a small project i am testing the use of mac terminal commands with C++, I
have started with the basic ones (ps aux, telnet etc, etc). I was wondering if there was any way to include a user input in the command sent to the terminal , eg entering the PID of the program you want to kill. Just in case it helps the code i am using is posted below.

#include <iostream>

int main()
{
 int proc;
 int PID;
 using namespace std;
 cout << "Welcome to the terminal tool for the common idiot\n";
 cout << "Please choose from the below options, which process you would like to perform";
 
 while(1)
 {
  cout << "(1) Show all running process's, (2) Telnet options, (3) Send Mail, (4) Kill application\n";
  cin >> proc;
  
  if (proc==1)
  {
   system ("ps aux");
   
  }
 
 if (proc==2)
 {
  system ("telnet");
  }
  
  if (proc==3)
  {
   system ("MAIL TO:");
   }
   
   if (proc==4)
   {
    cout << "Enter PID (obtained via process 1)\n";
	system ("kill") ;
	
	}
	
	else
	{
	 cout << "that is not a valid response, please select an option from the menu\n";
	 }
	 }
	 }

 

[fredthefool]

Stringstream

a stringstream (#include<sstream>) is your friend: due to his overloaded <<-operators, you can write to and concatenate strings in the same manner you would 'stdout'. to get a real string out of the stream, use his str()-method. and get a c-string out of it for the system-command needs this form of param. there are helpful subclasses istringstream and ostringstream.

ostringstream os;
os << "YOUR_COMMAND " << param_string;
system((os.str()).c_str());

the param_string can be keyed in at runtime ("cin") or extracted from argv[].
(and it wouldn't be bad to catch the return value of the system-command in a if-condition)

 

[jmac555]

Slightly confused?

so should it now read?

#include <iostream>
#include <sstream>

int main()
{
 int proc;
 int PID;
 using namespace std;
 cout << "Welcome to the terminal tool for the common idiot\n";
 cout << "Please choose from the below options, which process you would like to perform";
 
 while(1)
 {
  cout << "(1) Show all running process's, (2) Telnet options, (3) Send Mail, (4) Kill application\n";
  cin >> proc;
  
  if (proc==1)
  {
   system ("ps aux");
   
  }
 
 if (proc==2)
 {
  system ("telnet");
  }
  
  if (proc==3)
  {
   system ("MAIL TO:");
   }
   
   if (proc==4)
   {
    cout << "Enter PID (obtained via process 1)\n";
	cin >> PID;
	ostringstream os;
    os << system ("pause") << PID;
    system((os.str()).c_str());
	
	}
	
	else
	{
	 cout << "that is not a valid response, please select an option from the menu\n";
	 }
	 }
	 }

 

[fredthefool]

better try this part:

[ -- snip -- ]

if (proc=="4") //generally, keyboard input delivers a string, so i prefer this
  {
    cout << "Enter PID (obtained via process 1)" << endl;
    cin >> PID;
    
    ostringstream os;
    os << "kill " << PID; // fill stringstream ...

    // check return value of operating system -- 0 if OK;
    if(system((os.str()).c_str())){
       cerr << "Command failure" << endl;
    }
}

[ -- snap -- ]