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Sed example,part 1

jason — Wed, 08 Jul 2009 05:48:00 +0000

In the UNIX world, we have a lot of options when it comes to editing files. Think of it — vi, emacs, and jed come to mind, as well as many others. We all have our favorite editor (along with our favorite keybindings) that we have come to know and love. With our trusty editor, we are ready to tackle any number of UNIX-related administration or programming tasks with ease.

While interactive editors are great, they do have limitations. Though their interactive nature can be a strength, it can also be a… Read the rest

Awk example, Part 3

jason — Sun, 05 Jul 2009 10:58:59 +0000

Formatting output

While awk’s print statement does do the job most of the time, sometimes more is needed. For those times, awk offers two good old friends called printf() and sprintf(). Yes, these functions, like so many other awk parts, are identical to their C counterparts. printf() will print a formatted string to stdout, while sprintf() returns a formatted string that can be assigned to a variable. If you’re not familiar with printf() and sprintf(), an introductory C text will quickly get you up to speed on these two essential printing functions. You can view the printf() man page by… Read the rest

Awk example, Part 2

jason — Sat, 04 Jul 2009 11:45:53 +0000

Multi-line records

Awk is an excellent tool for reading in and processing structured data, such as the system’s /etc/passwd file. /etc/passwd is the UNIX user database, and is a colon-delimited text file, containing a lot of important information, including all existing user accounts and user IDs, among other things. In my previous article, I showed you how awk could easily parse this file. All we had to do was to set the FS (field separator) variable to ":".

By setting the FS variable correctly, awk can be configured to parse almost any kind of structured data, as long as there… Read the rest

Awk example, Part 1

jason — Fri, 03 Jul 2009 06:30:58 +0000

In defense of awk

In this series of articles, I’m going to turn you into a proficient awk coder. I’ll admit, awk doesn’t have a very pretty or particularly "hip" name, and the GNU version of awk, called gawk, sounds downright weird. Those unfamiliar with the language may hear "awk" and think of a mess of code so backwards and antiquated that it’s capable of driving even the most knowledgeable UNIX guru to the brink of insanity (causing him to repeatedly yelp "kill -9!" as he runs for coffee machine).

Sure, awk doesn’t have a great name. But it… Read the rest