/*
* Simple program to demonstrate the fork/exec/run sequence for creating
* processes in Unix.
*/
#include <iostream>
#include <string>
using namespace std;
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
int main()
{
/* Ask for a program to run. This is just the file name of an
executable. */
cout << "What shall I run? ";
string cmd;
getline(cin, cmd);
/* Request a single parameter. */
cout << "Would you like a parameter for that? (return for none) ";
string parm;
getline(cin, parm);
/* Create a child process and try to run the program in it. */
if(fork() == 0) {
if(parm.length() > 0)
execl(cmd.c_str(), cmd.c_str(), parm.c_str(), NULL);
else
execl(cmd.c_str(), cmd.c_str(), NULL);
cout << "Sorry, the exec failed." << endl;
exit(1);
}
/* See what was the cause of the child processes' demise. */
int status;
wait(&status);
if(WIFEXITED(status)) cout << "Exited." << endl;
else if(WIFSIGNALED(status)) cout << "Killed." << endl;
else cout << "Mysteriously vanished." << endl;
}
/*
* Note: This program really should check the return values for fork() and for
* exec() to make sure they succeeded, and print an error message if not.
* Failure is indicated by a negative return value. It would also help to use
* errno and strerror() to print a descriptive error message in place of the
* existing exec() failure message, or for the new messages.
*/