Tuesday, June 07, 2011

The truth of the kernel

For various reasons I sometimes have to know what Linux kernel I'm using with Ubuntu.  It's easy, but I always forget how, so this is as much for my own use as anything else:

To find your current Linux kernel, at the command prompt:
uname -r (quick, short reply)
uname -a (same with a little more information)
The difference between those two is that -r just tells you the version of the Linux kernel.
l@l:~$ uname -r
That's pretty straightforward.  The first two numbers, in this case the 2 and the 6, are major and minor releases.  The third number, 32, is the version.  The fourth number, 21, reflects the back-ports that are incorporated into the kernel.

An rc.x at the end means the version is a release candidate, the last revisions before a version is ready for use.

If you're curious, you can browse through the history of Linux 2.6.x.  Or back to the very beginning.  If you want to how Linux kernel numbering has changed over the years and why it changed, you can read the history, complete with primary documents.

Chances are, you're using an operating system that makes use of the Linux kernel, like Ubuntu, Red Hat, Open SUSE and so forth.  These are sometimes called "flavors" of Linux.  Frankly, I find they all taste the same, but they look and operate a little differently.

By using -a, you'll get a response like this:

l@l:~$ uname -a
Linux l 2.6.32-21-generic #32-Ubuntu SMP Fri Apr 16 08:09:38 UTC 2010 x86_64 GNU/Linux

Another way to get information about your kernel is by looking at the /proc file.  The command is:
cat /proc/version
The result, will look like this:

l@l:~$ cat /proc/version
Linux version 2.6.32-21-generic (buildd@yellow) (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) ) #32-Ubuntu SMP Fri Apr 16 08:09:38 UTC 2010
What does it all mean?  
  • Linux version 2.6.32-21-generic The complete Linux version.
  • (buildd@yellow) The username and host name of the person who compiled the kernel.  Thanks buildb, home everything's going well at yellow.
  • (gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5) ) The version of the compiler buildb used.
  • #32-Ubuntu SMP The type of the kernel (SMP means Symmetric Multi-Processing, which means the kernel makes use of multi-core processing)
  • Fri Apr 16 08:09:38 UTC 2010 The time and day that the kernel was compiled.

Git a minute: organize your email, the easy way

Get a lot of email?  Sometimes it hard to keep the inbox from growing.  It's tempting to go through it as quickly as possible, skimming the important stuff, saving some for later and deleting the rest.

Those last two things (saving and deleting) offer you some opportunities to get control of your inbox, rather than just getting through it. And if you do it strategically, you can do in in a minute, literally.

Each time you clear your inbox, take a minute to set up a filter that handles the saving or deleting of one message.

Here's an example: the online statement from your gas company, an investment account, or your mortgage.  If you use Gmail (or another web mail service) you can click:

More actions > Filter messages like these

And then set some rules for handling the message, like storing it for the day you pay bills, permanently storing it (if it's on autopay), or starring it so it's an obvious priority when the next one comes in.

You can do that in 60 seconds.

With some creative use of the filtering rules, you can be amazingly precise in what you do with what message, like highlighting a bill you have to pay, but saving or deleting the company's newsletter, even if they come from the same email address.  You can learn some tips and tricks here.

If you get Facebook alerts, you can star responses to things you've posted, save for later other messages and delete the list of birthdays.

If you commit to permanently handling one message each time you read email, in a week you'll notice how much faster you can get through your inbox.