Since this is for your System Programming course, I won't give you the exact answer here, but I can definately give you enough to help

"..teach a man to fish.."

cjf, myself, and others discussed this briefly on the CB soon after it was posted, and I gave up a few ideas on how to solve this. First a few key questions have to be asked:

1. Will you have access to create character devices on the target machine?
2. Will you be able to rebuild a kernel or reboot the kernel on the target machine?
3. Can you run a daemon on the user machine, global to all processes?
4. Are you limited to using pure perl? Or can you use C also?

With this, you could begin to construct several plans of attack:

• Write a kernel module (does not require a reboot, but requires sufficient access to load it into userspace) which will log all calls through the kernel keyboard driver to a file via normal kernel printk() mechanisms.
• Create a character device in /dev that you can peek from and write to a file (requires root access to create devices)
• Set up a userspace daemon that polls for input, a 'shim' between keyboard driver and input application.
• Work with Inline::C and integrate it with your perl code

Some other modules you may be able to use at your disposal are:

• Net::Daemon to create your daemon process in userspace.
• IPC::open3 to allow you to open a process for for reading/writing/error reporting
• Standard pipe() function for opening and dealing with your system calls..
• The source to xev, the X Event Interface could give you some ideas also

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