// Execute bash commands

// - firstly by hardcoding them

// - then take them directly from the command line



#include <unistd.h>

#include <stdio.h>

int main (int argc, char * argv[]) {

    // exec functions, if successfull, overwrite the current process

    // so if you want to test one of the execs below, comment out the ones above it



    // execl and execlp are variadic functions (can take a variable number of arguments)

    printf("Running execl\n");

    if(-1 == execl("/usr/bin/ls", "/usr/bin/ls", "-l", "-a", NULL)) {

        perror("Error on execl");

    }

    printf("Done with execl\n");



    printf("Running execlp\n");

    if(-1 == execlp("ls", "ls", "-l", "-a", NULL)) {

        perror("Error on execlp");

    }

    printf("Done with execlp\n");



    // execv and execvp take an array of strings as arguments

    // the array must obey the same rules as argv (first element must be the command itself, last element must be NULL) so we can actually pass argv to execv

    // here, we want to run 

    // ./exe cmd arg1 arg2 ...

    // since argv[0] = "./exe", we'll skip it and pass the array starting with position 1, which can be done in a few ways: &argv[1] or argv + 1 being two examples

    printf("Running execv\n");

    if(-1 == execv(argv[1], &argv[1])) {

        perror("Error on execv");

    }

    printf("Done with execv\n");



    printf("Running execvp\n");

    if(-1 == execvp(argv[1], argv + 1)) {

        perror("Error on execvp");

    }



    return 0;

}