If by exit you mean exit the loop and continue the script after the loop, you can use the last function to drop out of a loop, something like:
...
while($in){
if($in =~ /exit/i){
last;
}
}
# Code will continue here
...
Here we are using a case-insensitive regular expression match to test for the user entering 'exit'. This means that the user can enter 'Exit', 'EXIT', eXiT', etc. and the loop will still terminate.
This may not be necessay, since in my original example, if the user presses the ENTER key without typing anything, the input will be an empty string after chomp() has removed the newline, which, in Perl, evaluates to false, and the loop terminates.
If, on the other hand, you mean exit from the script without, for instance, printing anything like in my original example, just replace last with exit in the example above.