Digitivity » HowTo

How to Manually Add Hosts in Windows, Linux, and OS/X

Digitivity — Mon, 24 May 2010 17:50:53 +0000

Normally when you want to access a server on the Internet, you specify its name, like “www.google.com”. What actually happens behind the scenes is that your computer finds out the “IP address” of where you want to go. The IP address is like the “telephone number” of a server. The IP address for Google is 64.233.181.104 .

Go ahead and try it, you’ll end up at Google.

If the IP address is a “telephone number”, then the name (like the name you enter for a number in your cell phone) is called a host name. “Host” is just another word for server or computer.

Anyway, normally all of this works automagically, and you don’t even notice it. Once in a while it may not, for example, in a home network, thus forcing you to type in numbers instead of names.

There’s a way to set hostnames to IP addresses manually.

The hosts file

It’s called a “hosts” file, and it works generally the same on Windows, Linux/Unix, and Mac OS/X.

The hosts file is a list of IP addresses followed by hostnames, separated by a space, like this:

64.233.181.104 www.google.com
192.168.0.4 myhomecomputer

By the way, there’s a neat little trick you can use to block ads by setting the address of adservers, like Double Click’s, to your local computer:

127.0.0.1 ad.doubleclick.net

Note: 127.0.0.1 is a special address that always refers to your own computer.

The hosts file’s location differs from system to system:

Setting hosts/IP address on Windows

On Windows 95, 98, and ME, the host file is at c:\windows\hosts .

On Windows NT, 2000, XP, Vista, and 7, it’s at C:\windows\system32\drivers\etc\hosts .

View your hosts file

You can modify it with Notepad (Accessories menu).

Setting hosts/IP address on Mac OS/X

In Mac OS X 10.2 or later, hosts is at /private/etc/hosts

To edit it, type this into a terminal (Applications > Utilities > Terminal)

sudo nano

Enter your own password if prompted, add a hostname entry, then press Ctrl+x to exit the editor, and save the modified file by pressing “y”.

You have to then flush the DNS cache (OS/X doesn’t do that automatically):

sudo dscacheutil -flushcache

More info: http://support.apple.com/kb/TA27291
http://www.leftcolumn.net/2009/07/04/adding-an-entry-to-etchosts-on-os-x/

Setting hosts/IP address on Linux/Ubuntu/Unix

On Linux and all other Unixes, hosts is at
/etc/hosts .

View your hosts file

You have to have either sudo or root privileges to edit it.

How to Download Movies with BitTorrent Using Miro

Digitivity — Wed, 27 Jan 2010 16:48:52 +0000

I covered installing Miro on Windows the other day.

Miro is a free and open source podcast downloader and viewer. You can also download and view torrents in Miro.

BitTorrent is a peer-to-peer media sharing network.

I wrote a guest post for the What’s Good Blog about BitTorrent and Miro.

Read about how to download movies with BitTorrent using Miro on the What’s Good Blog.

How to Claim Your Blog on Technorati

Digitivity — Fri, 22 Jan 2010 17:29:14 +0000

Once you’ve signed up for a Technorati account, you should claim your blog.

Claiming your blog allows you to use Technorati tags to drive traffic to your blog from Technorati, which is the biggest blog search engine and aggregation site on the Internet.

Before Technorati associates a given blog on the Internet with your Technorati account, it needs to verify that that blog is under your control. It does this by giving you a unique code, and asking you to use that code within a blog post.

Once you post the code, you tell Technorati to check your blog.

Claiming Your Blog

After you’ve signed up for an account at http://technorati.com/account/signup/ , go to your Technorati account profile at http://technorati.com/account/ and

Click on “Claim a blog” and enter your blog address (with the http://).

Technorati tells you that it’ll send you an e-mail with blog claim instructions:

Claim Technorati Blog: Claim Status

In my case it was about 15 minutes before I received the e-mail.

The e-mail tells you to use a specific code and also check your account profile for more info:

Claim Technorati Blog: Claim E-mail

When you go to your Technorati account profile for more information, click on “Check Claim“.

You’re shown your blog’s claim status:

Claim Technorati Blog: Blog Claim Status (2)

Here’s what it says

Technorati will need to verify that you are an author of the blog by looking for a unique code. Please put the following short code MFD767KGRM88 within a new blog post and publish it

All this means is that you need need to have the claim code in the text of your blog entry. For me, I’ve already done that since the code is quoted above.

After you’ve published the blog entry with the claim code, go back to the claim status page and click the Verify Claim Token button.

Claim Technorati Blog: Verify Claim

Technorati then goes to your web site and verifies your claim token.

Enabling Ctrl+Alt+Backspace to Kill X in Linux and Ubuntu GNOME

Digitivity — Sat, 16 Jan 2010 13:11:07 +0000

Earlier this year, X.org made a boneheaded move to drop the Ctrl+Alt+Backspace key combination as a default for killing the X Server.

Huh?

The X Server is the part of a Linux operating environment that provides graphics. Once in a while it may lock up, usually due to bad drivers. Other times programs just happen to be taking up all memory, or other problems that you don’t want to wait for ever to resolve by themselves. A quick fix is to just kill X (which also kills graphical applications), and restart it. (You don’t have to restart it, even, in distributions that are set up that way. In Ubuntu, X starts up again automatically.)

OK, ever since the beginning the time or of Linux, or something like that, Ctrl+Alt+Backspace has been the key combination to kill X. Earlier, this year, though, somebody (who shall remain nameless to prevent the ire of countless old Linux hands) changed X.org (the X server most often used with Linux) to not respond to Ctrl+Alt+Backspace.

I thought that the reasoning behind the move was ridiculous. It had something to do with Windows users accidentally hitting Ctrl+Alt+Backspace (does anybody do that?) and with a conflict with some Emacs key combinations.

Here’s what one upset user said:

I will tell you that this argument about
confusion is totally bogus from an entire Linux community standpoint. The Emacs community is miniscule in size comparison to the overall Linux community. In over thirty years of working with *nix systems and thousands of users and machines not once has a user ever complained about confusion or problems involving the Ctrl-Alt-Backspace key combination. I am concerned because it appears that a tiny minority of Emac users have managed to lobby for a very significant change in default behavior for X server control to the detriment of the majority of users and administrators in the Linux community.

Disabling X’s DontZap to reenable Ctrl+Alt+Backspace

The response was that you can reenable Ctrl+Alt+Backspace by making an entry in /etc/xorg.conf, the X configuration file:

Section "ServerFlags"
Option "DontZap" "false"
EndSection

Well, OK, but the point was about the defaults. By default it would be handy to have Ctrl+Alt+Backspace already enabled so you can use it when you have a crash. Or when someone else does so you can tell them what to do about it.

Anyway, there’s one small problem: there’s no DontZap option anymore! They took that one away too!

Actually, they put the option into XKB (keyboard manager).

Reenable Ctrl+Alt+Backspace in GNOME/Ubuntu

In Ubuntu Karmic 9.10 (and probably other distributions running the GNOME desktop environment), it’s very easy to reenable Ctrl+Alt+Backspace. Just open the keyboard preferences dialog from the System: Preferences menu:

Ubuntu Karmic: Opening Keyboard Preferences

On the Layouts tab, hit Layout Options:

Ubuntu Karmic: Keyboard Preferences

This brings up the Keyboard Layout Options dialog.

Ubuntu Karmic: Keyboard Layout Options: Ctrl-Alt-Backspace

Open up the option for “Key sequence to kill the X server“. Check the box next to “Ctrl+Alt+Backspace”.

That’s it.

Reenable Ctrl+Alt+Backspace in KDE and the command line

You can do the same thing in KDE and the command line. See here for details:
https://wiki.ubuntu.com/X/Config/DontZap

Other ways to regain control without killing the X server

It’s much handier to have enabled this before a hang. But, if you haven’t, there are still a few options other than turning the computer on and off.

The first thing I often do if there’s a problem with X is to switch into a virtual console. That’s a text-based console where you can run a Bash shell. To do this press Ctrl+Alt+F1 (hold down Control, then also Alt, then also F1). Then you can log in with username and password.

From there, you can run top to find out the offending program. I usually run htop, which is a nicer and easier program list than top and kill the program from there or exit and run kill -9 or killall from the command line. For example, let’s say VLC is hogging memory. I’ll do:

killall vlc

This kills all vlc instances. This is often all that is required to return X back to normal, and so I don’t have kill X as well. After all, why use a cannon when a fly swatter will do?

Note: another key combination to be aware of is Alt+SysRq+R. This puts the keyboard into raw mode, meaning the hung X server won’t be processing key input. Then do Ctrl+Alt+F1. You’ll probably want to hold down the right Alt because the left one in combination with SysRq gives you a screenshot.

Showing Excerpts Instead of Full Posts on the Home Page in WordPress

Digitivity — Tue, 29 Dec 2009 17:46:47 +0000

Some of my posts have been getting longer and longer, especially how-to’s. It’s hard to scan the front page for articles, and I thought it was time to switch from full posts to excerpts on the home page.

Why have excerpts instead of full posts on your home page

Some reasons you might want to show excerpts instead of full posts on the home page include:

It can be difficult for readers (new and old) to get a quick overview of your latest articles when they have to page down a couple of times to get to the next article headline.
Search engines don’t like duplicate content on your website. So it’s better to have your content on single pages as opposed to both home and single pages.
The fact that a user has to click on an article to read it means that you get feedback on which articles your readers like. If they read the entire article off the front page, you don’t know if they read the article, or closed their browser immediately after loading your homepage.

Why have full posts instead of excerpts on your home page

On the other hand,

Some people believe the “no duplicate content” rule to be overblown.
Having full content on the home page makes it easier for people to read without constant clicking.
Having full content on your home page instead of excerpts means you get full content in your RSS feeds as well, which many of your readers may find handy.
Having full content on your home page means more text which often results in some combination of keywords which can be a match for a user’s Google query. I don’t know if that’s the kind of random traffic you want, though.

Before you switch

In the end, I decided to go with excerpts because my digital how-to’s were getting to be longer than 6 pages (i.e., six times pressing the Page Down key in a typical-sized browser window). Having to page down six times just to see what the next article’s title is seemed to me to be too much to ask readers to do. With excerpts, you can now page down just five times to see all the latest articles.

But before you do anything, be sure to make a full backup of your WordPress installation, including the MySQL database.

Creating single.php and editing index.php to show excerpts

OK, the file that WordPress uses to generate the home page is called index.php. You can also have a file called single.php that generates the “single pages” which display a single blog post per page. If you don’t have a single.php, WordPress uses index.php for double duty.

But since we want the home page to look different from single pages, we have to have a separate single.php. Just copy the index.php file as-is to a new file called single.php.

Now, we have to edit index.php. Do this with a text editor, or from WordPress administration (Appearance: Editor). If you use the WordPress Editor, look for Main Index Template.

Look for text that says the_content():

 the_content(); ?>

Replace it with:

 the_excerpt(); ?>

That’s it!

Click here to read this entry

OK, but now after reading the excerpt, the reader has to now go back to click your blog post title to actually read your full post.

Let’s make it easy by adding a link that reads “Read the rest of this entry”:

 the_title(); ?>" href=" the_permalink(); ?>">Read the rest of this entry ...

Note that I wrapped the link in h3 tags to make the link larger, more visible, and easier to click. This is what it looks like:

Read the rest of this entry …

Save the file and reload your homepage to verify the changes.

Thanks to Pro Blog Design for this excellent tip.

Excerpts in RSS feeds, and tags, categories, and archive pages

Note that by making these changes, your RSS feeds, and tags, categories, and archive pages will show excerpts as opposed to full posts.

You can get fancy by coming up with various combinations of having or not having full posts vs. excerpts on the front page, RSS feeds, tag pages, etc. with various other edits or plugins, but that’s the basics.

You can also show your entire latest post (or latest x number of posts) in full with the rest as excerpts. Again, that’s for later.

Default excerpts

By default, WordPress shows the first 55 words of your article as an excerpt. It also strips all tags and formatting and just shows plain text.

Some people use plugins to show full sentences and not break in the middle of an excerpt.

But I actually prefer the default which does break sentences. Think about it: if your phone conversation gets cut off, don’t you call back to listen to what the other party was saying? A break in a sentence actually makes me want to click the link just to complete the sentence.

Excerpt word count

If you want to check what 55 words amounts to, you can (among other methods), use the wc command in Linux (which is most likely what your web host provider is using). At the command prompt,

type wc -w:
paste your first paragraph or so right into the command shell
press Enter
press Ctrl+d

js@webhost:~/$ wc -w

wc responds with the word count:

Some of my posts have been getting longer and longer, especially how-to's. It's hard to scan the front page for articles, and I thought it was time to switch from full posts to excerpts on the home page.
 
Why have excerpts instead of full posts on your home page
 
Some reasons you might want to show excerpts instead of full posts on the home page include:
66

66 is the word count.

Resources

Display Post Excerpts Only in WordPress

Template Tags/the excerpt « WordPress Codex

How to Rename Files as Lowercase in Ubuntu Linux Recursively

Digitivity — Sun, 27 Dec 2009 21:08:38 +0000

Some reasons you might want to lowercase your filenames include:

1. Most webservers are case-sensitive. Because of this, most websites stick to the rule of having all files in a single case, namely lower.

2. If you’re using the command line to manipulate files, it’s easier when all the files are lower case. It’s a lot faster to type in all one case.

But it’s too time consuming to rename each file individually, so here are a few ways to rename. These are adapted from the commandlinefu website. (But the commands there have some bugs, so keep reading here.)

Renaming all the files in the current directory from uppercase to lowercase

rename 'y/A-Z/a-z/' *

This uses the rename script which is included with Perl, which in turn uses Perl’s rename function.

Most Linuxes and Unixes include Perl these days, including most web hosts. It’s easier and more succint than the alternatives.

Renaming all files from uppercase to lowercase in the current and subdirectories recursively

The way to do this is to feed rename a list of all files in the current directory and its subdirectories:

find . -type f -print0 | xargs -0 rename 'y/A-Z/a-z/'

Here’s what it means:

find prints a list of all files in the current and all subdirectories, recursively. -type f means only print the names of files, and not directories.

The | takes the output of the first command and sends it as input to the second command.

xargs takes the input (which is a list of files) and executes rename once for every filename, while appending the filename to the end of the rename command.

Normally, find puts a newline between each filename. But since a file’s name can also contain newlines, you make find delimit the filenames with a null character (ASCII 0). You do this by specifying the -print0 option. But you also have to tell xargs not to view newlines or spaces as filename delimiters, but rather only the null character. You do that with the -0 option.

Renaming files to lowercase without using Perl

Occasionally, you might not have access to Perl.

In such cases, you can use straight POSIX shell commands:

find . -type f|while read f; do mv "$f" "$(echo $f|tr '[:upper:]' '[:lower:]')"; done

This is an alernative that’s faster:

find . -type f -execdir sh -c 'mv "'{}'" "$(echo '{}'|tr '[:upper:]' '[:lower:]')"' \;

How to Add an E-mail to a Gravatar Account

Digitivity — Thu, 24 Dec 2009 19:56:31 +0000

Your Gravatar account can have more than one e-mail associated with it.

Gravatars are so-called “Globally Recognized Avatars” which allow you to show your choice of image (photo, drawing, whatever) alongside the comments you make on your own or others’ WordPress blogs.

You might find it handy to have multiple e-mails associated with your Gravatar account:

to avoid every blog out there from knowing your main e-mail (remember, WordPress is often hacked).
to avoid allow you to section off the damage if one of your e-mail addresses becomes compromised. If you get spam addressed to a given address, you can block just that one e-mail.
to post to different categories of blogs with different pictures. For example, a dignified picture for responding to work-related blogs, and a fun one for personal comments on various blogs.

To start, go to gravatar.com, log in and select “Add an Email Address” from the “My Account” menu.

Gravatar Add Email: Start

Gravatar asks you for the e-mail to add:

Gravatar Add Email: Specify Email

Enter the e-mail address you want to add, and hit Enter. Gravatar doesn’t add the e-mail automatically, but rather sends a confirmation e-mail to the address you entered. This is to prevent people from associated e-mail addresses that they don’t own:

Gravatar Add Email: Confirmation Email Sent

Go to your e-mail account, and go to the confirmation link in the e-mail that Gravatar sent you:

Gravatar Add Email: Confirm Email Address

Gravatar will activate the e-mail for use with Gravatar and then ask you to select an image to use with that e-mail (if you have more than one image):

Gravatar Add Email: Email Confirmed, Choose Image

Select an image, and confirm it:

Gravatar Add Email: Confirm Image

OK, now you’ve added another e-mail to use with your Gravatar account. And you can keep your main e-mail (that you used to sign up with Gravatar) private.

Resources

Blogs covering adding multiple e-mail addresses to a Gravatar account include the WordPress blog and Leonid Mamchenkov.

How to Show a MessageBox in Java Swing

Digitivity — Sat, 23 May 2009 13:11:23 +0000

VisualBasic and a lot of other languages have a handy function to show a message box to the user. In typical Java fashion, Java’s equivalent has a lot more power, but also complex.

To get simple message box functionality, you have to specify a number of options:

JOptionPane.showMessageDialog(parent,
    "Message",
    "Title",
    JOptionPane.INFORMATION_MESSAGE,
    icon);

This shows a dialog with your message plus a look-and-feel defined icon which varies depending on the option selected. For example, a question mark icon is shown for JOptionPane.QUESTION_MESSAGE. The various message types are shown below for the default Swing Metal look-and-feel:

Java Swing MessageBox: PLAIN_MESSAGE

Java Swing MessageBox: INFORMATION_MESSAGE

Java Swing MessageBox: QUESTION_MESSAGE

Java Swing MessageBox: WARNING_MESSAGE

Java Swing MessageBox: ERROR_MESSAGE

Note: the icon can be null if you don’t want or need an icon. You should specify a parent component (such as a JFrame) if you want the dialog to be modal with respect to that component. If you don’t mind that the user can click on something else and ignore your dialog message, leave it null.

If you want to get a response from the user as opposed to simply having him click OK, use the JOptionPane.showConfirmDialog() series of methods.

How to synchronize audio and video in VLC

Digitivity — Mon, 08 Sep 2008 17:15:46 +0000

Sometimes, a video’s audio isn’t synchronized with video for some reason or another. To sync audio and video on the fly in VLC:

In VLC 0.9.4: press Ctrl+k to increase delay, and Ctrl+l to decrease delay.
In VLC 0.8.6: press k to increase delay, and j to decrease delay. That’s without holding Ctrl.

If you decrease delay below 0, you will then be, in effect, delaying the video.

Each press of the key combinations changes delay by 50 ms.

How to Play a Quicktime Movie That Isn’t Playing in Your Browser

Digitivity — Mon, 07 Jul 2008 16:08:25 +0000

Even though Flash FLV movies have become something of an Internet standard, some sites persist in presenting movies in Quicktime format. Here’s how to view them if you have trouble playing them in your browser.

Reasons Quicktime movies might not play in your browser might include:

You don’t have the latest Quicktime plugin installed.
You don’t care to launch the Quicktime plugin.

I usually skip embedded Quicktime movies just because the plugin is so heavy. It takes a while to start up, and it takes up additional memory after it’s done. This is unlike the Flash plugin, which is always loaded since it’s needed for so many websites.

So what I do is just do a “View Source” on the page (View: Page Source in Firefox). Then I search for the Quicktime movie URL. You can do this by searching for the text string “.mov”. An example would be:

Just get the URL:

http://www.colorguides.net/movies/pantone_solid_colors_movie.mov

Take it and paste it into VLC at the File: Open dialog.
Of course, this means that you need to have VLC installed, but you should already have it installed.