Learning Perl, Fourth Edition

Exercises

See Appendix A for answers to the following exercises:

1. [6] Write a program that changes to some particular (hardcoded) directory, like the system’s root directory, and executes the ls -l command to get a long-format directory listing in that directory. (If you use a non-Unix system, use your own system’s command to get a detailed directory listing.)

2. [10] Modify the previous program to send the output of the command to a file called ls.out in the current directory. The error output should go to a file called ls.err. (You don’t need to do anything special about the fact that either of these files may end up being empty.)

3. [8] Write a program to parse the output of the date command to determine the current day of the week. If the day of the week is a weekday, print get to work; otherwise, print go play. The output of the date command begins with Mon on a Monday.^[336] If you don’t have a date command on your non-Unix system, make a fake program that prints a string similar to one that date might print. We’ll give you this two-line program if you promise not to ask us how it works:

       #!/usr/bin/perl
       print localtime() . "\n";

^[336] At least when the days of the week are being given in English. You might have to adjust accordingly if that’s not the case on your system.