To Beep or not to Beep

Seems like Linux has done everything to prevent anyone from controlling the I/O devices under /dev, which includes you. I had a simple task, I wanted my "mail-notification" program to beep when I had mail. Under "When new mail arrives:", there was the command "play /path/to/some/sound.aiff" or something... I don't want any process interrupting my sound card because I'm running Fedora Linux, and I don't have JACK or another sound mixer which will mix sounds from multiple processes (maybe one day ALSA will work like this).

So anyway, I tried a million different commands...

echo -ne "\a"

which prints just a bell character, but it's interpretted by mail-notification (or nothing) and is lost--not sounded on the system beeper.

I tried a C program by Johnathan Nightingale, beep, which I had lying around, but it fails because the kernel doesn't like it touching the devices.

Finally, I thought "hmm, beep.c is just writing to /dev/console, why can't I?" and I tried

echo -ne "\a" > /dev/console

And it worked! It's not the same beep as Thunderbird/xterm/emacs, but it's fine with me!

Executing a command on multiple files with FIND

Okay, so apparently, the FIND command is so powerful that you can even tell it what to do with the files when it finds them. I always used to find multiple files, translate newline characters to null characters, then pass each argument to XARGS as in:
find ./ -regex ".*\.mp3" | tr \\n \\0 | xargs -0 -n 1 md5sum > mp3checksums.md5

But, you can also say:
find ./ -regex ".*\.mp3" -exec md5sum {} \; > mp3checksums.md5

Where, the {} implies to insert an individual argument into that part of the exec string, and the semicolon (escaped so it's not picked up by BASH) ends the -exec agrument.

Computer Internal Dust Solutions

It seems like opening up my computer (or multiple in my case) and blowing it out every month is releasing too much dust back into the air, and all those particles that were stuck in there can wreak havoc upon your moving parts (fans). Assuming you operate electronic devices which have ventilation fans indoors, try the following.

Get a HEPA filter and run it, at least on its lowest setting, all the time.
The electricity it takes to run such filters is completely eclipsed by how much dust they remove from the indoor air and prevent those particles from being stirred up again. It's better for human breathing, and better for devices with moving parts. Also, if the filter circulates the air, your components might run cooler.

Install low-impedance dust filters in front of your computer's ventilation intakes.
Many computer cases are already shipping with single-layer plastic mesh filters which will stop most huge dust particles (the ones you can see anyway). I decided to give it a shot and installed some extra dust filters on the intakes of two computers. One computer had side ports which were completely open (no, fan, just big holes). NOTE: If you have filters installed, air will follow the path of least impedance, so either block or put filters over all air passageways that flow into the case. Don't put filters on exhaust ports (ports which blow out).
I decided to use WEB Vent Filters, but these have a few drawbacks: they have fibers which come loose, and are higher impedance than the coarse foam. Coarse foam like that in SHOP*VAC Foam Sleeves is preferred for low impedance of air flow, but doesn't offer good filtering of smaller particles. Both are readily available at the local hardware store.



I put WEB Vent Filters on the outside of the case (so they wouldn't get sucked into the fan) for one, and in between the case and the air duct for the other. On the other computer, I took the front panel off, and installed the filters over the intake fans, but under the outer cover. The only concern I have now is cleaning these. I'm hoping that after the one-to-two month interval, I can vacuum the filters externally to clear large debris back out through the intake, and then the next interval I can remove them and wash them under water.


WARNING: Remember, the foam should be low impedance! Any dust filter you install over a ventilation port or fan will impede the flow of air through your device. Fans will spin a little faster, but air flow will be slower. Make sure this doesn't cause any heat issues, and either remove the filter or install more fans if necessary. Inevitably, over time the filters will become clogged and become further impeding, and will require replacement or washing.

Vacuum and dust often.
I know, this is common sense, but I've seen people who just have a million Duster cans and they blow out their computer whenever it starts to make noise. Grinding noises are a very bad sign--this means that something is on or around the fan's journal (which usually has ball bearings), and the fan will most likely fail if not cleaned. Oiling the fan's journals using three-in-one motor oil can help, but the best bet is to keep the fans free from particles beforehand, and replace them when things start to go awry. Rule of thumb: if you have to clean it out more than once every one to two months, you have a dust problem. Also, blowing the dust around can cause a fan assembly to become dirty.

Finally, keeping these computer systems away from sources of dust is a good idea. Major sources of dust include laundry, bedding, and animals and humans.