Change the modification time of /bin/bash to the system time. What happens? Why?

Question

Copy /bin/bash to the working directory, display its modification time,

and then change its modification time to the system time. Display the modifi-
cation time of your copy of bash and the system time. Change its modification

time to January 5, 2018 at 2:34 PM and display its modification time.

Answer 1

$ touch /bin/bash
touch: cannot touch `/bin/bash': Permission denied
The system displays a Permission denied error message. For reasons of secu-
rity, as a nonroot user you are not permitted to change most system files.
$ cp /bin/bash .
$ ls -l bash
$ touch bash
$ ls -l bash
$ date
$ touch -t 1801051434 bash
or
$ touch -d 'January 5, 2018 2:34 PM' bash
$ ls -l bash