Easy segregation of systems by MAC address
ISC's DHCP server lets you classify clients by many factors, including substring matches on the MAC address, allowing for simple DHCP server configs to seperate clients.
In my environment, there are workstations that host desktop VMs in VirtualBox, and servers that host backend systems, research and per-course VMs in KVM and OpenVZ, with VMWare, Xen and LXC as possibilites.
Each vendor that produces networking (or virtual networking) devices has their own MAC address ranges, and can be identified by the first three bytes of the address.
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aggravation
Very short.
When running vncserver on a gnome system (seems to happen especially often with VMs...), gnome decides to have the modifier key down permenantly.
How do you know if you're having this problem? When you press "d", all your windows minimize, for one thing....
After that everything is just so aggravating you can't think to remember what else is going wrong.
As your user, or root, just run this:
gconftool-2 --set /apps/metacity/global_keybindings/show_desktop --type string "disabled"
Then restart your vnc server.
Basically, it tells gnome to cut out it's stupid keymapping that you didn't want anyway.
Graybeards rejoice! Our android tablets are computers again.
Years ago, when I first saw a PalmPilot, I became enamored with the idea of having a small portable computer I could program. Well, the pilot ended up being too wimpy, and despite better specs, my VTech Helio was worse both in it's native OS and in linux. When I finally got the first Compaq iPaq it was nothing short of amazing, but I was forced to face the sad truth that I can't program on a screen that small. I don't know if anyone can program on a screen that small.
Years pass, and android is born, grows up, and put on reasonable tablets... and I get that urge again to program not just for the device, but on the device. Despite having less storage, a good android tablet of today has better computational specs, better screen resolution and less weight than the eeePC netbooks that were so popular just a few years ago.
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No warrantee, express or implied
OSX doesn't come with seq. If you're a traditional linux/unix sysadmin, this will drive you insane.
Compile it yourself, or download it from here if you're in a rush, don't have xcode installed to get GCC, etc.
seq.bz2
I compiled from the 2.0 sources here. There's nothing special to do: untar, ./configure and compile, then copy seq out. You could make install if you really wanted to, but it might not be a great idea. Who knows?
I would suggest you put it in ~/bin /opt/bin or /usr/local/bin, but that's only because putting non-vendor/distro software in /bin and /usr/bin irks me.
It's so easy, every other OS should emulate this sort of move
Today I had to pull two dead drives out of a Mac Mini server. That part is a minor pain, but this is an old Mac Mini (A1283), and I've heard the new ones are easier to disect. Minor, because if you can take something apart with two pocket knives, a jewelers screwdriver and ifixit, it can't be considered a major pain.
Moving the OS to the new drives was a simple matter of choosing the "restore" option from Disk Utility, select the source and target, and wait for it to finish. Oh, and it did it live, running off the source HDD: something I've never been able to do effortlessly on other unicies. I've done it, but it was so far from effortless, that booting into recovery media to move the OS from drive to drive is still the way to go. LVM in linux comes close, but there's still grub or lilo to deal with, and some shops don't like LVM (for whatever reason).
I don't like the lack of well documented command line tools in OSX, I dont' like some of Apple's changes, but there are some things, like this, that really should be emulated in the rest of the unix world.
While I feel more kinship for the other Steve of Apple, I held Steve Jobs in the highest respect and admiration.
So goodbye to the great man. He sold computers for home when no one thought you could. He sold more unix systems than Sun, sold more creative computers than SGI, more useful computers than HP, and gave us user interfaces that looked like they could have come from a movie.
He put georgous unix systems into the hands of select consumers with NeXT, and then turned those ideas into OSX, a unix grandma could use: whether she was a farmgirl, or a retired mainframe programmer.
He had them scale OSX down to iOS, and put unix boxes into the pockets of 128,964,000 people around the world.
Goodbye Steve. You did well by us unix users. You did well by every computer user. You did well by everyone who uses the devices you ushered into being.
Thanks.
Because Apple doesn't make it easy, unless you're on OSX Server
Enabling SNMP on OSX is made easy in server, but on their client versions, not so much. If you're used to unix, the first place you look is in /etc/, and try and find the init scripts. OSX likes to burry it's unix roots, so that's a dead end. Luckily, they do put all the daemons in the same place.
/System/Library/LaunchDaemons
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Time observation
I resized two mdadm raid 5 arrays this week. Both are comprised of four 1.5TB drives. Previously they used three discs, with the fourth a hot spare. I grew them to include the spare, so each has a raid 5 comprised of four drives, and it's using all four. After the start of this semester, I'm getting an extra drive for each array, which I will use as the new hot spare.
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