Category: Computer Related

StayFocused

“You sit down at the computer, and you swear you’ll be productive. Next thing you know, it’s twelve hours later. You’ve checked your email, updated your Facebook status, browsed the trending topics on Twitter, read your RSS feeds, [read Reddit, my drug of choice,] looked up your favorite band on Wikipedia, vanity googled yourself, cyber-stalked your ex, looked at all your high-school crushes’ Facebook photos, watered your plants on Farmville, and lost a week’s pay playing online poker. 

What you haven't done is WORK.
StayFocusd is a productivity extension for Google Chrome that helps you stay focused on work by restricting the amount of time you can spend on time-wasting websites. Once your allotted time has been used up, the sites you have blocked will be inaccessible for the rest of the day."

Of course, you have to be running Chrome.

Task management: Toodledo, http://www.toodledo.com.  Different than Remember The Milk, maybe better.  I’m trying it out and may switch permanently.

I hate it when my internal model of a program doesn’t quite match its actual behavior.

So I’m tailing a file: “tail -f file”.  Tail recognizes when a file’s been truncated and starts rereading it.  BUT, even if you say “-n +0” it still starts rereading from the new end, not from the beginning.  So if you have

# Terminal 1
date > file
tail -f -n +0 file

# Terminal 2
date > file
date > file
date > file

You’ll never see anything new from tail, because the length of the file never actually changes.

More subtly, say you have

# Terminal 1
date > file
date >> file
tail -f -n +0 file

# Terminal 2
date > file

Here the tail will see that you truncated the file, but it won’t show you the new line, because the file length changed from 58 to 29, not from 58 to 0 to 29.

All that’s fine and maybe even “obvious” when laid out like that.  But you can get the same behavior like this:

# Program 1, pseudo-Perl
open LOGFILE, “>file”;
while (my $request = get_request()) {
    print LOGFILE “the requestn”;
    process( $request );
}

# Terminal 1
tail -f -n +0 file

When you restart Program 1, you won’t see the first request in the log file, because just as above, the file length went from (say) 100 to 50, not 100 to 0 to 50.

But if you cat the file, there it is.

Anyway, I hate it when that happens.

(The answer, by the way, is to unlink the file before you start writing to it again, and tell tail “–follow=name”.)

• Time synchronization is briefly documented in the manual in chapter 9, Advanced Topics.
• Time synchronization is performed by an in-guest daemon called VBoxService
• You can tune VBoxService (on the guest) by running VBoxManage on the host.  As near as I can tell, you must restart VBoxService for any changes to take effect.  (In Debian, /etc/init.d/vboxadd-service restart.  To kill it, replace “restart” with “stop”.  To start it after you’ve killed it, replace “restart” with “start”.)
• You can watch what VBoxService does by killing the daemon (see above) and running it from the command line in verbose mode, in the foreground (as root), “VBoxService -v -f“.
• By default, VBoxService wakes up every 10 seconds and adjusts the time.  If the time is off by less than 20 minutes, it adjusts the time by (very roughly) 0.005 seconds.  (Put another way, if your clock is slow by a whole second, it may take half an hour to catch up.)  If the time is off by more than 20 minutes, VBoxService just sets the time.
• If you want VBoxService to just set the time when it’s off by more than 1 second (1000 ms), instead of adjusting it gradually every 10 seconds, you can say
  • VBoxManage guestproperty set <vm-name> "/VirtualBox/GuestAdd/VBoxService/--timesync-set-threshold" 1000
• The “--” in the documentation and in the command above is not a typo.
• Remember to restart VBoxService for your changes to take effect.

I wanted to run Linux on my Mac laptop, but didn’t want to pay $80 for VMWare Fusion if I could avoid it.  It turns out, I could!  I’m not actually done installing Linux yet, but VirtualBox seems pretty nice so far.