Write a program that calls fork() and then calls some form of exec() to run the program /bin/ls. See if you can try all of the variants of exec(), including execl(), execle(), execlp(), execv(), execvp(), and execvpe(). In your submission, you may pick one with which to run /bin/ls. Why do you think there are so many variants of the same basic call

Assignment: permutations use the permutation formula   r ! ! n n p nr   to solve each problem. be sure to show all work leading to your answer. part i: solve real-world permutation problems choose any four (4) of the following five problems to solve. for each problem a) show how the permutation formula can be used to find the answer and b) write a sentence to explain the meaning of the answer for the situation. 1. to register for online banking services at a local credit union, you need to select a four-digit personal identification number, or pin code. the digits cannot be repeated. how many ways are there to arrange four digits out of the numerals 0 through 9 to create a code?