I recently meant to run the command `pkexec`, but accidentally managed to run the command `exec` by itself with no options or arguments. I looked in the `man` pages for the description of `exec`, but I still have no idea what it means:

```
DESCRIPTION
       The  exec() family of functions replaces the current process image with
       a new process image.  The functions described in this manual  page  are
       front-ends  for execve(2).  (See the manual page for execve(2) for fur‐
       ther details about the replacement of the current process image.)

```

And actually the description goes on... But the rest of the description didn't help me very much either... So this is really my question, what does the `exec` command do? And did I do anything by just executing it by itself with no options or arguments, just as `exec`? Does it have any relation to the `pkexec` command?