I have been given an assignment where I have to create a small shell that the user will be able to enter in a path and 2 parameters. The shell must be able to process this input and run the program at the given path using execvp, and must also parse the parameters. I must use Fork() and Wait() along with that.
I've been able to get the users input, and have it print out what that input was. The problem lies in when I try to do the execvp() method, the program says that it was unable to run my program, or it will just wait for another command but not do anything. The only time I was able to get my shell to start a new program was when I used execl() method instead and I entered the path to the program staticly (instead of getting user input, just set the path manually).
Here is the code I'm using at the moment:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#define BUFFER_MAX (50)
#define MAX_ARGS (4) //Maximum parameters
main() {
struct command_struct {
char *name; //Name of the path
char *argv[MAX_ARGS]; //The parameters
char input[BUFFER_MAX]; //Users input holder
} *myCmd;
char *out = "<Command>";
//Intro:
printf("\t\tWelcome to the shell command line interpreter!\n"
"\t\t Please enter your command to execute:\n%s", out);
//Get user input:
while (fgets(myCmd->input, sizeof (myCmd->input), stdin) != NULL) {
//Get name of the command:
strncpy(myCmd->name, strtok(myCmd->input, " "), sizeof (myCmd->input) - 1);
//Construct the parameters:
myCmd->argv[0] = strtok(NULL, " ");
myCmd->argv[1] = strtok(NULL, " ");
pid_t pid = fork();
//FORK:
if (pid < 0) {
printf("%sError running %s", out, myCmd->name);
} else if (pid == 0) { //Child
//Execute the command with params:
execvp(myCmd->name, myCmd->argv);
perror("execvp failed to run");
exit(-1);
} else { //Parent
wait((int *) 0);
}
printf("%s", out);
}
}
//EOFI would be very grateful with any information I can receive to better understand how to create this shell! Thank you
