Update: Firefox 3.0 final has become available from the official fedora updates repository. It seems that the technical issues of the past do not exist any more! Kudos! This tutorial will still give you an idea though about how to quickly and easily switch between the default and custom versions of the same software in your system.

Fedora 9 has been used as the desktop system for this article. The provided information will certainly work in CentOS and RHEL, but might also work for other linux distributions which use the alternatives system, such as Debian, Ubuntu, OpenSUSE etc. As far as I know, Gentoo and its derivatives use their own system.

In order to check if “alternatives” is available in your system, try one of the following commands:

which alternatives
which update-alternatives

Firefox Installation

First of all, we install a precompiled (binary) Firefox distribution, downloaded from mozilla.org, in the /opt directory. All the following commands should be issued by ‘root‘ or by your regular user using ‘sudo‘.

Change to the /opt directory, download and extract the firefox package:

cd /opt/
wget ftp://ftp.mozilla.org/pub/firefox/releases/3.0/linux-i686/en-US/firefox-3.0.tar.bz2
tar -xjf firefox-3.0.tar.bz2

Now change to the /opt/firefox/ directory, delete the plugins/ subdirectory and create a symlink to the system’s directory containing the firefox plugins (/usr/lib/mozilla/plugins/ in Fedora).

cd firefox/
rm -fr plugins
ln -s /usr/lib/mozilla/plugins/ plugins

The installation of the custom Firefox version is complete.

Set the system-wide default Firefox version

In this section we will use the alternatives system in order to provide us with two options:

1. Use Fedora’s default Firefox release. This means that /usr/bin/firefox should be executed whenever we issue the ‘firefox‘ command.
2. Set our custom Firefox release as the system’s default. This means that /opt/firefox/firefox should be executed whenever we issue the ‘firefox‘ command.

Note: Describing the details of the alternatives system is out of the scope of this article, so it is highly recommended that you study the alternatives manual page (man 8 alternatives)

In the following steps we will add a group, named “firefox“, of alternative options for the location of the firefox executable. These options are actually filesystem locations which will be linked by the /usr/local/bin/firefox symlink. Note that we use the /usr/local/bin/… path for our symlink, because /usr/bin/firefox is occupied by fedora’s firefox executable. The latter will not be called directly any more, as the executables located in /usr/local/bin/ override the ones located in /usr/bin/, so whenever the command ‘firefox‘ is invoked, /usr/local/bin/firefox will actually be used. The latter is a symlink, which links to either fedora’s firefox executable or our custom firefox executable.

So, we add the ‘firefox‘ group of options:

/usr/sbin/alternatives --install /usr/local/bin/firefox firefox /usr/bin/firefox 10
/usr/sbin/alternatives --install /usr/local/bin/firefox firefox /opt/firefox/firefox 20

Now we can manually set which firefox executable to use as the system’s default. In other words, the following command links /usr/local/bin/firefox to the desired executable (/opt/firefox/firefox in our case):

/usr/sbin/alternatives --set firefox /opt/firefox/firefox

Instead of the --set option as shown above, we can use the –config option, so that a list of the available alternatives is displayed and we are prompted to make a selection:

# /usr/sbin/alternatives --config firefox
There are 2 programs which provide 'firefox'.
  Selection    Command
-----------------------------------------------
   1           /usr/bin/firefox
*+ 2           /opt/firefox/firefox
Enter to keep the current selection[+], or type selection number: 2

Finally, we can issue the following command to get an overview of our current configuration for the group ‘firefox‘:

# /usr/sbin/alternatives --display firefox
firefox - status is manual.
 link currently points to /opt/firefox/firefox
/usr/bin/firefox - priority 10
/opt/firefox/firefox - priority 20
Current `best' version is /opt/firefox/firefox.

Revert to the original state

If for any reason you need to revert things back to the default state, all you have to do in order to remove all the “alternatives” we had configured in the previous section is the following:

/usr/sbin/alternatives --remove firefox /opt/firefox/firefox
/usr/sbin/alternatives --remove firefox /usr/bin/firefox

No other configuration is required. From now on, whenever the ‘firefox‘ command is invoked, fedora’s old /usr/bin/firefox is executed.

Final Thoughts

Technical issues in the linux distribution preparation process might limit the user to certain software versions. The alternatives system provides users with the choice to configure the system in a way that it is extremely easy to switch between default and custom versions of the same software.

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For all those who have not tried Epiphany yet, I’d like to say the following:

Using Epiphany is not about reaching the sense of uniqueness by using a less popular browser. It is also nowhere near trying to seem elite. Moreover, you will never manage to impress the ladies by using it…

Epiphany is a tool; a stable, lightweight piece of software, which offers better integration into the GNOME environment than any other browser, the powerful engine of Firefox and some of the most futuristic features that are available among today’s web browsers, for example tagged bookmarks.

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">

Then visit the W3C Markup Validation Service and start validating your webpages. Alternatively, you may want to add a hyperlink somewhere in your theme’s footer, which will point to a specific page on the validator’s web site, which will automatically examine the referer of the request; that is your page that needs validation. Add the following hyperlink:

<a href="http://validator.w3.org/check/referer">Validate XHTML</a>

If your current theme is well-made you won’t be needing major modifications.

Below there is some info about the changes that required significantly more time than others, because of the many occurencies throughout the theme and the plugins’ code.

1 – The <script> element does not have a language attribute any more, so:

<script language="Javascript" type="text/javascript">

… should become just:

<script type="text/javascript">

2 – Named anchors, like:

<a name="blah"></a>

…should become:

<a id="blah"></a>

3 – The border attribute should be removed from the <img> element.

4 – Finally, the target attribute that was frequently used inside <a> elements in order to specify the target frame is not included in the XHTML 1.1 specification. Fortunately, there is a decent workaround for this.

Instead of the:

<a [...] target="_blank" [...] </a>

… one could use some Javascript code to open the hyperlink in a new frame:

<a [...] onclick="window.open(this.href); return false;" onkeypress="window.open(this.href); return false;" [...] </a>

Apart from this, there is another way to pass the XHTML 1.1 validation test, even if you use the target attribute. This is because XHTML has been modularized. By default only 4 core modules are included, but one can create a very own document type definition (DTD), which may inlude the target or any other module. The new DTD can then be uploaded somewhere on the net, so that people can link to it from within their pages DOCTYPE declaration. More information about this and an example can be found here.

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Copy the file to your bbPress root directory, decompress it and apply it:

$ gunzip registration-functions.php.patch.gz
$ patch -p0 -b < registration-functions.php.patch

Here follows the full patch:

--- bb-includes/registration-functions.php	2007-07-10 13:29:56.000000000 +0300
+++ bb-includes/registration-functions.php.new	2007-07-10 13:29:50.000000000 +0300
@@ -41,11 +41,10 @@
 	$resetkey = bb_random_pass( 15 );
 	bb_update_usermeta( $user->ID, 'newpwdkey', $resetkey );
 	if ( $user ) :
-		mail( bb_get_user_email( $user->ID ), bb_get_option('name') . ': ' . __('Password Reset'), sprintf( __("If you wanted to reset your password, you may do so by visiting the following address:
-%s
-
-If you don't want to reset your password, just ignore this email. Thanks!"), bb_get_option('uri')."bb-reset-password.php?key=".$resetkey ), 'From: ' . bb_get_option('admin_email') );
+		$message  = sprintf(__("%s,\n\nA request to reset the password for your account has been made at %s\n\nIf you wanted to reset your password, you may do so by visiting the following address:\n\n%s\n\nIf you don't want to reset your password, just ignore this email. Thanks!\n"), "$user->user_login", bb_get_option('uri'), bb_get_option('uri')."bb-reset-password.php?key=".$resetkey );
+		$message .= sprintf("\n______\n%s\n%s [%s] %s %s\n", __("Password reset request details:"), $_SERVER['REMOTE_ADDR'], gethostbyaddr($_SERVER['REMOTE_ADDR']), __("at"), date("Y-m-d\TH:i:sO"));
+		mail( bb_get_user_email( $user->ID ), bb_get_option('name') . ': ' . __('Password Reset'), $message, 'From: ' . bb_get_option('admin_email') );
 	endif;
 }
@@ -62,7 +61,7 @@
 			bb_block_current_user();
 		if ( !$user->has_cap( 'change_user_password', $user->ID ) )
 			bb_die( __('You are not allowed to change your password.') );
-		$newpass = bb_random_pass( 6 );
+		$newpass = bb_random_pass( 8 );
 		bb_update_user_password( $user->ID, $newpass );
 		bb_send_pass           ( $user->ID, $newpass );
 		bb_update_usermeta( $user->ID, 'newpwdkey', '' );
@@ -85,7 +84,7 @@
 	return $user_id;
 }
-function bb_random_pass( $length = 6) {
+function bb_random_pass( $length = 8) {
 	$number = mt_rand(1, 15);
 	$string = md5( uniqid( microtime() ) );
  	$password = substr( $string, $number, $length );
@@ -98,7 +97,8 @@
 	$user = $bbdb->get_row("SELECT * FROM $bbdb->users WHERE ID = $user");
 	if ( $user ) :
-		$message = __("Your username is: %1\$s \nYour password is: %2\$s \nYou can now log in: %3\$s \n\nEnjoy!");
+		$message = __("%1\$s,\n\nThank you for registering at %3\$s.\n\nYou may now log in at %3\$sbb-login.php using the following username and password:\n\nusername: %1\$s \npassword: %2\$s \n\nAfter logging in, you may want to visit %3\$sprofile-edit.php so you can change your password.\n");
+		$message .= sprintf("\n______\n%s\n%s [%s] %s %s\n", __("Registration request details:"), $_SERVER['REMOTE_ADDR'], gethostbyaddr($_SERVER['REMOTE_ADDR']), __("at"), date("Y-m-d\TH:i:sO"));
 		mail( bb_get_user_email( $user->ID ), bb_get_option('name') . ': ' . __('Password'),
 			sprintf( $message, "$user->user_login", "$pass", bb_get_option('uri') ),
 			'From: ' . bb_get_option('admin_email')

I hope WordPress does not mess up the backslashes.

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• Run through cron at predefined intervals. In this case it reads the saved rtorrent session data, creates a summary about the loaded torrent files status and prints the HTML code to stdout, which can then be redirected to a file and thus be made publicly available by a web server.
• Run as a CGI script, which makes it possible to dynamically generate the HTML page on-demand. This method, compared to running rtorstat through cron at short pre-defined intervals, has the advantage of limiting system resource waste by parsing the session data only when a user runs the CGI script through the web browser. Also, depending on your rtorrent settings, the displayed information is usually more current than that of the HTML page generated through cron, unless cron runs the script very often.

rtorstat does not support or will never support any kind of remote rTorrent administration. It is not supposed to be a web-based rtorrent frontend, but, as the title says, a simple status page generator (status web interface).

Requirements

rtorstat is not dependency-free. Here is the list of the required software in order to run rtorstat:

• Python
• rTorrent (configured to save session data – see below)
• The file “bencode.py“, part of the official Bittorrent client (Mainline) distribution, has been included in the rtorstat distribution package, so the Mainline Bittorrent client is no longer a dependency for rtorstat.

rTorrent Configuration

rtorstat needs to read the torrent session data, so rTorrent needs to be configured to save this information to a pre-defined directory. The following shows all the session-data specific configuration rTorrent (.rtorrent.rc) options:

# Sets the directory where session data files are stored
session = /opt/bittorrent/sessiondata
# Keeps session data files even if torrent has finished
session_on_completion = yes
# Not really required, but recommended - see rtorrent(1) man page
session_lock = yes
# Setup A: Run through CRON
# Save session data every 5 mins, with a 4 min offset
schedule = session_save,240,300,session_save=
# Setup B: Run as a CGI
# Save session data every 300 seconds
# (This is an example value. Setting it to a lower value is highly recommended)
#schedule = session_save,300,300,session_save=

The last directive (schedule) instructs rtorrent to save session data at the specified interval.

Usage

rtorstat can be run through cron or as a CGI script. Running it as a CGI is the preferred way of running it as the parsing of the session data and the HTML page generation take place dynamically only when you visit the web page. This leads to wasting less system resources.

Running rtorstat through cron

No special installation is needed as the location of rtorstat.py can be set within the cron job. Just make sure that the file bencode.py exists in the same directory as rtorstat.py.

rtorstat requires one argument; that is the path to the directory where the session data is saved:

$ python rtorstat.py /opt/bittorrent/sessiondata/

Having parsed the session data files and having created the summary, the HTML code is printed to stdout, from where it can be redirected to a html file. For example:

$ python rtorstat.py /opt/bittorrent/sessiondata/ > /var/www/index.html

rtorstat is supposed to be run through cron at regular intervals. In the example configuration above (Setup A), rtorrent saves the session data every 5 minutes (300 sec), so rtorstat needs to be run at the same interval through cron. The 4 min offset (240 sec) that had been set in the rtorrent scheduler serves so that there is good timing between rTorrent saving the session data and rtorstat parsing it.

Such a cron job would be:

*/5 * * * *   root python /path/to/rtorstat.py /opt/bittorrent/sessiondata/ > /var/www/index.html

rtorstat will parse the session data files, for example, at 00:05, 00:10 etc.

Having adjusted the paths according to your configuration, save the above cronjob to a file inside the /etc/cron.d/ directory and you are set.

Running rtorstat as a CGI script

In this case, you need to place 3 files in your cgi-bin: rtorstat.py, rtorstat.cgi and bencode.py.

Apart from the rtorrent configuration, it is required to set the path of the directory where rtorrent saves session data in rtorstat.cgi. So, open rtorstat.cgi in your favourite text editor and fill-in the required information:

session_dir = "/path/to/rtorrent/session/dir/"

Now, you can visit the web page http://yourdomain.example.org/cgi-bin/rtorstat.cgi

Setting up a scriptaliased directory is covered by your web server’s documentation and is outside of the scope of this document.

Security

rtorstat generates a HTML page which is made publicly available through a web server (most probably). Therefore it is your responsibility to secure this location using any of your web server’s access control methods.

License

This project is released under the terms of the Apache License version 2.

Download

All versions of the software, including the latest stable release, are available from the development web site’s download area.

Donate

This software is released as free software. Nevertheless, its development requires time and effort. A small donation, as a sign of appreciation of the effort, is welcome. Please, use the following button to visit the Donations page. Thank you.

Support

This software is released as free software without any warranties or official support. You can still get first class support from the community of users.

Bugs and Feature Requests

Found a bug? Want to suggest a new feature for the upcoming release? Feel free to file your requests in the issue database on the development website.

Things to consider

It has been mentioned before, but here it goes again:

Note that by making the rtorrent status page publicly available through a web server, the world will know what you download at any time. It is your exclusive responsibility to keep this page private, if this is what you really want. This piece of information is of course beyond the scope of this article.

This script was written in a quick and dirty way. If you encounter any bugs, please notify me through the g-loaded forums and I will get back to you when I have the time.

Last, but not least, if you improve the looks, consider contributing back your string template.

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How to create a smart (dynamic) bookmark

This is quite easy. Assume that you need to create a smart bookmark that searches the archives of your favourite mailing list.

All you need to do is perform a search on that list for a distinctive sequence of characters. For example I searched the LGU list for the term AAAAAA:

AAAAAA site:http://lists.hellug.gr/pipermail/linux-greek-users/

Or better, you may want to use Google’s advanced search feature.

Now, all you have to do is bookmark (Ctrl-D) the results page, but before actually saving the bookmark, you should substitute the AAAAAA sequence with %s. (that’s two characters % and s)

%s will be substituted with the requested search terms every time the smart bookmark is used.

Now, your bookmark is a smart one and you may finally press the “Add” button to save it. All you have to do is type the search terms on the browser’s address bar and choose your smart bookmark from the bottom of the dropdown list that appears below the address bar.

Another cool thing you can do with a smart bookmark is to open the bookmarks editor (Ctrl-B), right click on your smart bookmark and select the “Show on Toolbar” option. A textbox should appear in your bookmarks bar, so you can search this resource quickly.

Finally, if you use the Deskbar applet, then you should know that this tool recognizes your saved smart bookmarks and lets you assign a shortcut to each one of them. For example, one could assign the “lgu” string to the aforementioned search on the mailing list archives. So now a search on the mailing list can be performed right from the desktop (deskbar applet) with the following:

lgu kernel

This will search the mailing list for all entries that contain the term kernel.

Smart bookmarks are a neat feature. I use this very frequently. This post was written for those who have overlooked this really useful feature.

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[Update]: Also, another resource of htaccess recipes exists here. I didn’t have the time though to go through all of their sections, but all .htacces rule examples seem very organized and well written too.

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Before proceeding, make sure you have backed up your current non-optimized style-sheet. CSSTidy will not touch your original file, but taking some precautions is a good habit.

Launch csstidy without arguments for a rather short description of the command line switches:

csstidy

Although it is possible to define each parameter individually, some pre-defined templates are what you will most probably use. These include: low|high|highest. The higher the optimization level, the smaller the CSS filesize. More on templates here.

I tried the high and highest templates. The latter produces a style sheet that contains all code in a single line, but that file would not validate, so I used the high template:

csstidy style.css --template=high style.css.out

The compression ratio for my file was 34.86% which was quite satisfactory. Also, the final file validated properly.

CSSTidy does a good job either you want to optimize the stylesheet for readability or for filesize. On the other hand, the CLI interface does not provide enough information about each of the CLI switches. They are pretty self-explanatory, but I guess a little description for each one of them wouldn’t hurt anyone. Also, I could not make the “--remove_last_;” option to work.

The only difference I could notice in my stylesheets between the high and the highest templates was that the whole code was squeezed in a single line when highest was used. Probably, this template performs some more optimizations than just deleting the line-feed characters, but it seems that there was nothing else that could be optimized in my CSS file.

Apart from this command line utility, there are also a lot of online CSS optimizers. I didn’t have the time to try them all, but I think I can recommend the following:

• Clean CSS – this seems to be the PHP version of CSSTidy. Everything seems to work as expected and the results are the same as before.
• Icey CSS Compressor – This is another web-based CSS optimizer which performs very well. By using the default settings you get a single line with highly optimized CSS code. The compression ratio is similar to CSSTidy’s. In order to separate each selector with a line-feed character, so that the final CSS validates, you can pass the optimized CSS through sed:

  sed -i 's/}/}\n/g' style.css.out

If anyone knows about any other utility I would be very glad to know about.

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• -I : when used, CURL prints only the server response’s HTTP headers, instead of the page data.
• -L : if the initial web server response indicates that the requested page has moved to a new location (redirect), CURL’s default behaviour is not to request the page at that new location, but just print the HTTP error message. This switch instructs CURL to make another request asking for the page at the new location whenever the web server returns a 3xx HTTP code.

The combination of the above two switches results in having all the server responses’ headers printed to the terminal, until CURL receives a code other than 3xx.

So, here is a real-life example. I have made two major changes to my web site so far; one included a URL structure modification when I moved from a pure HTML web site to WordPress, while the second was a domain change from the free domain raoul.shacknet.nu to the current paid domain name. So, this makes at least two permanent redirections. I say “at least”, because other necessary redirections could take place as well, for example, redirections of the example.org version of the domain to the www.example.org version, or redirections required for permalinks.

So, here is CURL’s output when I requested an old page of my web site:

$ curl -I -L http://raoul.shacknet.nu/servers/vnc.html

HTTP/1.1 301 Moved Permanently
Date: Fri, 06 Oct 2006 01:49:06 GMT
Server: Apache/2.2.2
Location: http://www.raoul.shacknet.nu/servers/vnc.html
Connection: close
Content-Type: text/html; charset=iso-8859-1
HTTP/1.1 301 Moved Permanently
Date: Fri, 06 Oct 2006 01:49:06 GMT
Server: Apache/2.2.2
Location: http://www.g-loaded.eu/servers/vnc.html
Connection: close
Content-Type: text/html; charset=iso-8859-1
HTTP/1.1 301 Moved Permanently
Date: Fri, 06 Oct 2006 01:49:06 GMT
Server: Apache/2.2.2
Location: http://www.g-loaded.eu/2005/11/10/configure-vnc-server-in-fedora/
Connection: close
Content-Type: text/html; charset=iso-8859-1
HTTP/1.1 200 OK
Date: Fri, 06 Oct 2006 01:49:06 GMT
Server: Apache/2.2.2
X-Powered-By: PHP/5.1.4
X-Pingback: http://www.g-loaded.eu/xmlrpc.php
Status: 200 OK
Connection: close
Content-Type: text/html; charset=UTF-8

The above output shows that the client has to send 4 HTTP requests and receive 4 respective responses from the server in order to reach that old page’s final location:

1. The first server response informs the client that the page has been permanently moved to the www version of the old domain.
2. The second response indicates that the page has been permanently moved to the www version of the new domain using the old URL structure.
3. The third indicates a permanent move to the new URL structure.
4. The final response informs the client with a 200 OK code that it has reached the page’s final location.

In this example, CURL provides a clear view of what situation a browser, a search engine bot or any other HTTP client encounters when it tries to reach an old page.

I am not an expert, but I guess that too many redirects are not a good thing, not only by considering the small increase of the server load, but also that search engine bots might not like them very much. On the other hand, redirections are a necessary evil if you want links from other websites pointing to your old domain or your old URL structure to continue to be valid, which in fact adds “value” to your website, as search engine experts would say. So it’s a matter of choice.

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