(This is on solaris, no -N option to diff for me!)

This produces the easiest-to-read diff IMO:
diff -btu [oldfile] [newfile] > patchfile
-b = ignore blanks
-t = preserve source indentation
-u = 3 lines of context with the + and - in front of changed lines

But the -t option interferes with proper patch application, so just use:
diff -u [oldfile] [newfile] > patchfile
…where oldfile is the file you want to patch, and newfile is the file with the changes you want to apply.

patch -b -p0 < patchfile
-b = make a backup

If you are asked for the patch filename - you probably don’t have the depth set right with -p.  Try increasing it.

If you get the message “Reversed (or previously applied) patch detected!”, somebody messed with your stuff between creating the patch & applying it, OR you did the diff backwards (common Monday morning mistake.)

Data from the PostgreSQL Job Task Analysis survey.

I shortened some questions and answers to better fit on the page; see original data if you are concerned about potential shifts in meaning. In many cases, I re-ordered the answers in a way that makes sense to me. Again, please see the original data if this concerns you.  Not all data has been graphed.  Graphs created in OpenOffice Calc.  I would have rather used Gnuplot, but I preferred the horizontal bar chart style & gnuplot can’t do that yet without a lot of gymnastics.

PostgreSQL JTA - Graphs

I’m learning a little Python for a side project. I wrote a SELECT statement that would produce NULLs and rather than use COALESCE to prevent returning NULLs, I wanted the application to be able to detect and then replace the value with a default.

In Perl, this is a no-brainer to me - the NULL value would be ‘undef’, and I could write something like:

$value = $default if (! defined $value);

So, after a bit of struggling, I found out that the ‘None’ object is returned when a value is NULL in python.

To determine whether you’ve got a NULL, you write something like:

if $value is None:
    $value = $default

Generally speaking, Python considers an undefined object to be a rare occurrence.

Here are the slides from my PDX.pm talk this week. A link to the accompanying podcast will be along soon.

Other fun things we discussed at the meeting:
Cisco::Reconfig
trapgen
logger
logwatch

Thanks for the lively discussion!

[edit] podcast!

[edit] Clarification of two items from the podcast:
- multiline messages do indeed come in multiple packets. There is a message counter that increments for each message, so you could use the host name + message counter to match up multi-line messages. For what I’m doing, the important part is in that first line, so the payoff isn’t worth the investment.
- re hypens in the mnemonic field of the system message: I went back through and wasn’t able to find any examples of this, so I retract my statement. (I do have examples of system messages with hyphens in the facility field.)

You need:
root/sudo access to a statically-addressed Ubuntu machine.  (It will need to be on whenever your router is on in order to get anything good out of this.)
Enable access to your Cisco router.

Part 1: Set up your log host.

Step 1: before editing any of the files discussed below, be sure to back them up, e.g.:
cp /etc/syslog.conf /etc/syslog.conf.dontmessthisup

Step 2: edit /etc/syslog.conf to include this:
#router logging
local6.debug                    /var/log/cisco.log

This means “send all messages from facility local6, with a priority of debug or greater, to /var/log/cisco.log”.

(Note that the default facility for Cisco is local7; if you want/need to use the Cisco default, change the above accordingly.)

Step 3: create the log file I specified above:
sudo touch /var/log/cisco.log
(more…)

I just wrote way too much about the talks I’ll attend to at PostgreSQL Conference West. Check it out!

Let me know what you’re planning to see in the comments!

-selena

Last night, an incredible number of people showed up to Code-N-Splode to hear about Git.

I was not at all prepared for that number of people, but grateful that a couple experts were on hand to help - Sarah Sharp, Audrey Eschright and Michael Schwern (and others) all contributed to the discussion. Thanks for all the great questions! I’m looking forward to Sarah’s advanced tutorial next month.

:bd - closes the current buffer window

CTRL-F - page down; CTRL-B - page up; CTRL-D - put current line in the center of your screen

CTRL-R - Redo (plus COUNT for redoing a number of changes); ‘u‘ is for undo; ‘U‘ is for undoing all changes on a particular line

:set undolevels=NUM - number of changes saved in memory (can set to negative number if running out of memory

:split - split your current window into two; switch between windows with CTRL-W CTRL-W

!{cmd} - run a shell command, shows you the output and prompts you before returning to your current buffer; ‘:!‘ by itself runs the last external command; ‘:!!‘ repeats the last command; :silent !{cmd} eliminates the need to hit enter after the command is done; ‘:r !{cmd}‘ puts the output of $cmd into the current buffer.

Gabrielle and I are at it again, talking about Filesystem I/O and Linux at the Linux Plumbers Conference.  Mark Wong is the evil performance genius working with us behind the scenes, and a copy of what we brought to the conference today is here.

Takeaway: Set your read ahead buffer size higher in the kernel - maybe even 8MB.

I’m learning the PostgreSQL system catalog tables right now, and was wishing that I had some catalog flashcards.  I made my wish ‘aloud’ on IRC today, and @davidfetter managed to blow my mind with this simple command-line switch for psql: -E. Now, every time I use a command, the tool tells me what the underlying SQL query is. Great for jogging the memory, and I’ll be putting off making my catalog flashcards for a few more days. Now I wonder what other revealing command-line switches I’ve overlooked!

See screenshot: