Question

I’ve separated a given command from the user into substrings , here’s the code :

     int i;

     char *line = malloc(BUFFER);
     char *origLine = line;
     fgets(line, 128, stdin);   // get a line from stdin


     // get complete diagnostics on the given string

     lineData info = runDiagnostics(line);

     char command[20];
     sscanf(line, "%20s ", command);
     line = strchr(line, ' ');

     printf("The Command is: %s\n", command);

     int currentCount = 0;                  // number of elements in the line
     int *argumentsCount = &currentCount;   // pointer to that


     // get the elements separated

     char** arguments = separateLineGetElements(line,argumentsCount);


     // here we call a method that would execute the commands


    if (execvp(*arguments,*argumentsCount)  < 0)       // execute the command
    {
                printf("ERROR: exec failed\n");
                exit(1);
    }

When I execute the command in execvp(*arguments,*argumentsCount) , it fails .

What’s wrong ?

Thanks .

EDIT :

The input from the user is : ls > a.out , hence I have 3 strings , which are :

ls , > , a.out , and it fails .

Answer 1

From man page of execvp command:

   int execvp(const char *file, char *const argv[]);

The second argument is a list of null-terminated C-strings as arguments to the command to be executed by execvp. But in your code, you pass an int as the second argument which is wrong.

If you have list of arguments in the variable arguments then call execvp as:

execvp(arguments[0],arguments);