She sells C shells by the seashore
By Christopher Nehren
March 16, 2009
In contrast to my previous post on tabs in vim, here’s a different way of managing multiple files, multiple SQL console sessions, multiple nearly anything. This works with any program that behaves well with regard to Unix job control, and really allows Unix to shine as an IDE in its own right. The emphasis here will be on using whatever tools are suitable to do the job, rather than on one specific editor. Note that the details given here will not work very well for network programs that assume a constant connection like an IRC client. However, at least the Postgres and MySQL consoles both support this feature, and they’re the only “networked” applications I can imagine using in this way. This post will focus more on a way of thinking than on technical know-how, though there is a bit of how-to mixed in.
Most readers are familiar with backgrounding a task at a Unix terminal with ^Z and then bg. Something that is less common, at least in my experience (in favor of GNU screen and the like), is using shell job control for anything more than detaching a running program from one’s terminal. When applied liberally, the tactic allows one to harness the power of Unix all via one login. To …
tips
End Point SEO with Linkscape
By Steph Skardal
March 12, 2009
Linkscape was released in October of 2008 and is SEOmoz’s collection of index data from the web that currently contains 36 billion URLs over 225 million domains. You must have a pro membership to access advanced reporting, but without a pro membership you can access basic data such as mozRank (SEOmoz’s own logarithmic metric for page popularity) for the url, number of links to a url, number of domains to a url, and mozRank for the domain.
For example, I ran a basic report on www.google.com and found:
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The mozRank of http://www.google.com/ is 9.36 out of 10
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There are ~96.8 million links to http://www.google.com/
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There are ~1.6 million domains linking to http://www.google.com/
More interesting data on www.facebook.com:
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The mozRank of http://www.facebook.com/ is 7.40 out of 10
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There are 0.9 million links to http://www.facebook.com/
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There are 60,000 domains linking to http://www.facebook.com/
Because I haven’t given justice to describing Linkscape, please read more about Linkscape, or see Linkscape Comic for visual enhancements.
Case Study
In an effort to examine and improve End Point’s search engine performance, I pulled together some snippets of data from Linkscape for …
seo
Vim tip of the day: tabbed editing
By Christopher Nehren
March 11, 2009
How many tabs does your browser have open? I have 17 tabs open in Firefox presently (and opened / closed about 12 while writing this post). Most users will agree that tabs have changed the way they use the Web. Even IE, which has spawned a collection of shells for tabbed browsing, now supports it natively. Tabs allow for a great saving in screen real-estate, and in many cases, better interaction among the various open documents. Considering how much time programmers spend in their text editors, it therefore seems logical that the editor should provide the same functionality.
And the Vim developers agree. Although Vim calls them “tab-pages”, the functionality is there, waiting to be used. Before reading any further, ensure that your Vim supports tabs. You can do this by running this command, on anything resembling Unix:
vim --version | fgrep +windows
If you don’t see any output, check your vendor’s packaging system for something like vim-full. If you don’t have a Vim available with the windows feature, go get one and come back.
Now that you can use tabs, let’s get started. One way to open tabs is via the command line. Vim uses the -p option to determine how many tab-pages to open. …
tips vim
Interchange jobs caveat
By David Christensen
March 10, 2009
I’d used Interchange’s jobs feature to handle sending out email expirations and re-invites for a client. However I found out the hard way that scratch variables persisted between individual sub-jobs in the job set. I’d tested each of the two sub-jobs in isolation and had had no issues.
This bit me because I’d assumed each job component was run in isolation and variables were initialized with sensible (aka empty) content. In my case it fortunately only affected the reporting of each piece of the job system, but definitely could have affected larger pieces of the system.
The lessons? 1) Always explicitly initialize your variables; you don’t know the ultimate context they’ll be run in. 2) Individual component testing is no substitute for testing a system as a whole; you can reveal bugs that would otherwise slip through.
interchange
Vim Tip of the Day: running external commands in a shell
By Selena Deckelmann
March 10, 2009
A common sequence of events when editing files is to make a change and then need to test by executing the file you edited in a shell. If you’re using Vim, you could suspend your session (ctrl-Z), and then run the command in your shell.
That’s a lot of keystrokes, though.
So, instead, you can use Vim’s built-in “run a shell command”!
:!{cmd}Run a shell command, shows you the output and prompts you before returning to your current buffer.
Even sweeter, is to use the Vim special character for current filename: %
Here’s :! % in action!
A few more helpful shortcuts related to executing things in the shell:
:!By itself, runs the last external command (from your shell history):!!Repeats the last command:silent !{cmd}Eliminates the need to hit enter after the command is done:r !{cmd}Puts the output of $cmd into the current buffer.
tips vim
Emacs Tip of the Day: ediff-revision
By David Christensen
March 9, 2009
I recently discovered a cool feature of emacs: M-x ediff-revision. This launches the excellent ediff-mode with the defined version control system’s concept of revision spelling. In my case, I was wanting to compare all changes between two git branches introduced several commits ago relative to each branches’ head.
M-x ediff-revision prompted for a filename (defaulting to the current buffer’s file) and two revision arguments, which in vc-git’s case ends up being anything recognized by git rev-parse. So I was able to provide the simple revisions master^ and otherbranch^{4} and have it Do What I Mean™.
I limited the diff hunks in question to those matching specific regexes (different for each buffer) and was able to quickly and easily verify that all of the needed changes had been made between each of the branches.
As usual, C-h f ediff-revision is a good jumping off point for finding more about this useful editor command, as is C-h f ediff-mode for finding more about ediff-mode in general.
git emacs
pg_controldata
By Josh Tolley
March 9, 2009
PostgreSQL ships with several utility applications to administer the server life cycle and clean up in the event of problems. I spent some time lately looking at what is probably one of the least well known of these, pg_controldata. This useful utility dumps out a number of useful tidbits about a database cluster, given the data directory it should look at. Here’s an example from a little-used 8.3.6 instance:
josh@eddie:~$ pg_controldata
pg_control version number: 833
Catalog version number: 200711281
Database system identifier: 5291243377389434335
Database cluster state: in production
pg_control last modified: Mon 09 Mar 2009 04:05:23 PM MDT
Latest checkpoint location: 0/B70E5B9C
Prior checkpoint location: 0/B70E5B5C
Latest checkpoint's REDO location: 0/B70E5B9C
Latest checkpoint's TimeLineID: 1
Latest checkpoint's NextXID: 0/307060
Latest checkpoint's NextOID: 37410
Latest checkpoint's NextMultiXactId: 1
Latest checkpoint's NextMultiOffset: 0
Time of latest checkpoint: Fri 06 Mar 2009 02:27:02 PM MST
Minimum recovery ending location: …postgres
Scout barcode artistry
By Jon Jensen
March 7, 2009
Once upon a time, UPC barcodes had to be pretty large for the barcode readers to work. That made the barcode roughly square. Some years ago newer standards came out and the barcodes were still the same width to maintain compatibility, but they could now be shorter, presumably because scanning technology had improved.
The combination of packaging that had space allocated for a tall barcode with the new reality that barcodes didn’t have to be tall was an invitation to creativity, as evidenced by the barcode on the box of this Scout Pinewood Derby kit I noticed today:
I love it—and the barcode is the only place on the box that the Scout emblem appears at all! Here it is closer up:
Has anyone seen this kind of artistically subverted but still functional barcode anywhere else?
art