LINUX NEWS
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Thursday, October 4, 2001
Read By Over 7,000 Linux Enthusiasts Weekly!TABLE OF CONTENTS
1) Sean’s Notes
2) Linux News
World's Greatest Editor
Time to stand up to Microsoft
Star Office 6.0 beta Released
The Freedom to use Codes3) Linux Resources
Programming Linux Games
SQL Databases for Linux
Information Warfare: How to Survive Cyber Attacks
Say Hello to PAM
Three Minutes With Security Expert Bruce Schneier4) App o’ the week
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1) Sean’s Notes
If there is something you find yourself doing often, it’s probably worth scripting. Even if it’s a matter of running a couple of other scripts, the goal is to save some time. It may seem like a waste of time at first, but add up all the time you spend doing the task, and think of what else you could be doing in that time. If it’s work-related, then wrapping it up in a script (well commented, of course), lets you get away with not having to explain it to everyone who does the task themselves, or has to fill in for you on vacation. It’s all part of our nature as Unix jocks to be lazy. Not “slacker lazy”, but “work smarter, not harder lazy”.
The more you learn about scripting, the more places you’ll find it to be handy. An example will help here.
Every week when I write this newsletter, I start off with a file called template.txt, which has placeholders for every news and resource item, plus the headers and footers. I copy it into a file called YYYYMMDD.txt, and begin my work on it. Once I’ve written the article and added the links in, two things remain before I submit it, namely spell checking, and filling in the “Table of Contents” section.
The latter is a real pain, and is the first thing that has to be fixed. After the first two weeks of cutting and pasting, I knew it had to be scripted. I came up with a simple solution – a Perl filter that extracts the headlines from the .txt file, leaving me with only two cut and pastes to do (versus nine plus a lot of scrolling). It’s actually a pretty simple script:
!/usr/bin/perl
while(<STDIN>) { if (/^-+$/){ $a=<STDIN>; print “\t$a”; $a=<STDIN>; } }
The outer loop reads in input from the standard input. Perl is a pretty relaxed language, so when I get the current line from the <STDIN> statement, it stores it in a special variable called $_ (that’s a dollar sign, followed by an underscore).
Next, I want to perform a regular expression search on the current line, to see if it is beginning the title of one of my links. Everything between the /’s is called the pattern, or a regular expression. In this case, the pattern begins with a carat, meaning “beginning of line”. Next is a dash followed by a plus sign. The plus sign means “match one or more of the preceding”. The final dollar sign means end of line. So, my regexp will only match a line that starts with a dash, ends with a dash, and has nothing but dashes in between. Since I already have the current line in $_, I don’t have to explicitly tell Perl where to look because it’s the default. Otherwise, I’d have to tell it to do a regular expression search with the =~ operator:
if ($_ =~ /^-+$/) {
Once I’ve found the line in question, I read the next line with my title, and print it (with a tab in front for easier pasting):
$a = <STDIN>; print “\t$a”;
And then, because the next line is also full of dashes, I do a fake read to advance the file to the next line.
This week, it looks like this:
$ cat 20011004.txt | ./makecontents.pl TABLE OF CONTENTS World’s Greatest Editor Time to stand up to Microsoft Star Office 6.0 beta Released The Freedom to use Codes Programming Linux Games SQL Databases for Linux Information Warfare: How to Survive Cyber Attacks Say Hello to PAM Three Minutes With Security Expert Bruce Schneier
A few clicks, and I’m done. Is that lazy enough for me? Not anymore. It’s been almost a year of cutting and pasting; it’s about time I had the script make the changes directly.
The template I start off with has the phrase “Headline” where I’m supposed to put the headline (shows how smart my editor thinks I am). I’m going to use that to my advantage now.
What I came up with (after several tries) is:
#!/usr/bin/perl -w
use strict;
# Need a filename to function
$ARGV[0] || die "Gimme a filename\n";
# Open one for reading, and a backup stream for writing
open FILE, "<$ARGV[0]" or die "Error opening $ARGV[0]\n";
open BACKUP, ">$ARGV[0].bak" or die "Error opening backup\n";
my $newsletter;
while(<FILE>) { # Run through the file
print BACKUP; # Write to the backup file
$newsletter .= $_; # All that we've read so far goes here
if (/^-+$/){ # We found the beginning of a header
my $a=<FILE>; # read it in
print BACKUP $a; # Write to the backup file
$newsletter .= $a;
unless ($a =~ /TABLE OF CONTENTS/) {
# Substitute the first "Headline" for the real one
$newsletter =~ s/[ \t]+Headline\n/\t$a/;
}
$a=<FILE>; # Read next line
print BACKUP $a; # Write to the backup file
$newsletter .= $a;
}
}
close BACKUP;
close FILE;
# Good work... update the original file
open FILE, ">$ARGV[0]" or die "Error opening $ARGV[0] for writing\n";
print FILE $newsletter;
close FILE;
I’ve added a lot of comments, but it’s basically the same thing as before, just not written as a filter (ie it reads and writes the files by itself). You’ll notice I write a backup copy as I go along, it’s just good practice! I’m not perfect, so I don’t expect my scripts to be. Everything is pretty basic, except the real smarts of the script:
unless ($a =~ /TABLE OF CONTENTS/) { # Substitute the first “Headline” for the real one $newsletter =~ s/[ \t]+Headline\n/\t$a/; }
Here, I’m skipping over the header for table of contents. Since I have the entire document up until the current line in memory, I can perform a substitution on it, replacing the placeholder headline, with what I actually read in. This is a handy thing in Perl:
$variable =~ s/old/new/;
substitutes “old” for “new” in $variable.
So, in my quest for eternal laziness, I spent a bit more time than usual on this article, but ended up with a script that saves me some repetitive work that I dislike. A few more lines, and it could fill in the date at the top, and maybe even run a spell check at the end. If only the status reports I have to write for my boss were as easy…Wait… This article gives me an idea!
Long live the [lazy] Penguin,
Sean mailto:swalberg@brainbuzz.com
Visit the Linux News Board at http://boards.brainbuzz.com/boards/vbt.asp?b2
2) Linux News
World’s Greatest Editor
VIM, the King of all editors (or at least a clone thereof), announces the release of 6.0. There’s a whole whack of new features added to make a great editor even greater.
http://www.vim.org/announce/vim-6.0
Time to stand up to Microsoft
This scathing attack on Microsoft’s desktop operating systems is too good not to pass along. The author calls on people to jump on the Linux bandwagon, citing that Microsoft’s new policies are making it even more cost-effective.
http://www.zdnet.com/zdnn/stories/news/0,4586,2815189,00.html
Star Office 6.0 beta Released
This version of StarOffice purports to be easier on memory, and doesn’t take over your entire desktop. Two things I immediately noticed were that setting up PDF output is very easy, and that TrueType fonts can be used (an extra step, but it is well documented). A vast improvement over 5.2…I’ll just hope it’s as stable.
http://www.sun.com/staroffice/6.0beta/
The Freedom to use Codes
Linux is all about freedom, which is why many Linux enthusiasts are also Cryptography buffs. In the wake of the US tragedy, there are now calls for increased restrictions on Crypto. A reporter reflects on the folly of such a plan.
http://news.cnet.com/news/0-1272-210-7320099-1.html
3) Linux Resources
Programming Linux Games
If you’ve got a bit of programming knowledge under your belt, and wanted to try your hand at writing games for Linux, this is the book for you. It covers the basics of the SDL API, along with some other game writing APIs, and develops a complete working game. Well written, and full of useful information.
http://itresources.brainbuzz.com/tutorials/tutorial.asp?t=S1TU1475
SQL Databases for Linux
“So you find you need to store some data on your Linux system, and are wondering what program to use… There are a vast array of database systems available for use on Linux. Some are simple, some sophisticated, some cheap, some expensive. One of the first things you ought to do is ask yourself what you need to do with the database, as that is critical to bringing the number of choices down from ‘stupendously bewildering’ to merely ‘astoundingly many’.”
http://freshmeat.net/articles/view/305/
Information Warfare: How to Survive Cyber Attacks
With all the news about terrorism and viruses lately, this book couldn’t have come at a better time. A very interesting read, “Information Warfare” covers the non-technical aspects of Cyber Terrorism and other attacks.
http://itresources.brainbuzz.com/tutorials/tutorial.asp?t=S1TU1467
Say Hello to PAM
PAM, the Pluggable Authentication Modules, can be a great thing if you know how to use them. This article from O’Reilly Net has some great instructions on the format of the configuration files, and the various modules available.
http://linux.oreillynet.com/pub/a/linux/2001/09/27/pamintro.html
Three Minutes With Security Expert Bruce Schneier
Any time Bruce talks, I’ll listen. This time it’s on security (or lack thereof) in Microsoft products, and the merits of full disclosure. He regularly speaks out on topics close to the UNIX world, such as freedom and Open Source.
http://www.pcworld.com/news/article/0,aid,63806,00.asp
4) App o’ the week
“2diskXwin” is a distribution of Linux that…guess what… fits on two disks. It features a web browser and Internet capabilities, so this could work as a very easy remote X desktop device.
http://www.mungkie.btinternet.co.uk/projects/2diskXwin.htm
(C) 2001 BrainBuzz.com. All Rights Reserved.
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