Thread: getting input from keyboard, passing to execvp

Hi, I'm trying to create a simple shell program that reads in a command from the keyboard and passes it to execvp to execute. I'm working in a Linux environment. I'm splitting the input line into a command (the first token) and arguments (the remaining tokens). For example, ls -l has ls as command and -l as the sole argument. The problem is that execvp does not recognize the first argument. If I input "ls -l", it executes just "ls" and drops the "-l." If I input "ls -l -a", then it executes "ls -a." If I input "ls," it doesn't execute anything. Any thoughts? Thanks! Here is my code:

Code:

#include <unistd.h>
#include <iostream>
#include </usr/include/errno.h>
#include </usr/include/sys/errno.h>
#include <string>

using namespace std;

int main(int argc, char *argv[])
{
        // issue prompt
        cout << "> ";

        // get input from user
        string inputStr;
        char inputStrArr[128];
        char * argArr[128];
        char separators[]   = " ,\t\n";
        char *token, *command;
        int numArgs = -1;
        int k;
        int i;

        getline(cin, inputStr);
        for(i=0; i<inputStr.length(); i++)
                inputStrArr[i] = inputStr[i];
	inputStrArr[i] = '\0';
	token = strtok(inputStrArr, separators);
	command = token;

        while( token != NULL )
        {
                token = strtok( NULL, separators );

                argArr[++numArgs] = token;
        }

        argArr[++numArgs] = '\0';
 
        // fork
        int childpid, flag;

        if ((childpid = fork()) == 0) // child code
        {
                cout << "Process ID: child: " << getpid();
                flag = execvp(command, argArr);

                if (flag < 0)
                {
                        perror("execvp failed");
                }
        }
        else if (childpid > 0) // parent code
    {
        cout << "Process ID: " << getpid();
    }
    else // fork unsuccessful
    {
        cout << "\nError: fork failed\n";
    }

return 0;
}