nixCraft Linux Sys Admin Blog

Free / Open-source Television Software for Linux Desktop Systems

Posted: 10 Apr 2008 04:44 PM CDT

Personally, I use tvtime - a high quality television application. Most apps allows you scheduling a TV program for recording with a TV tuner, and burn to DVDs. Some program also support rss feed for TV program schedule.

Jun Auza has published a nice list of open-source television software:

Watching live or recorded TV feeds using a desktop computer is made possible using television software. Most TV software applications nowadays are integrated into media center programs with playback support for almost all kinds of media contents such as audio, video, image files and even RSS feeds.

To those who are using Linux and are looking for some television software, then you are in luck because there are plenty to choose from. Here is a list of some of the best free / open-source television software that you may want to try out

nsupdate Dynamic DNS Update Utility for Linux / UNIX

Posted: 10 Apr 2008 04:23 PM CDT

nsupdate is really cool tool.

nsupdate is used to submit Dynamic DNS Update requests as defined in RFC2136 to a name server. This allows resource records to be added or removed from a zone without manually editing the zone file. A single update request can contain requests to add or remove more than one resource recored.

=> Using the dynamic DNS editor: nsupdate

Stop Hotlinking with Lighttpd

Posted: 10 Apr 2008 06:59 AM CDT

The technology behind the World Wide Web, the Hypertext Transfer Protocol (HTTP), does not make any distinction of types of links -- all links are functionally equal. Resources may be located on any server at any location. Linking to an image stored on another site increases the bandwidth use of that site even though the site is not being viewed as intended. The complaint may be the loss of ad revenue or changing the perceived meaning through an unapproved context.

Here is easy and simple way to stop hotlinking :
Open lighttpd.conf file:
$ vi lighttpd.conf

#### stop image hijacking (anti-hotlinking) $HTTP["referer"] =~ ".*BADDOMIN\.com.*" {         url.access-deny = ( "" ) #      url.access-deny = ( "jpg", "png", "js", "jpeg", "gif" ) }

You can also enforce password protection:

$HTTP["referer"] =~ ".*BADDOMIN\.com.*" {  auth.require = ( "/" =>                    (        "method"  => "digest",                             "realm"   => "Authorized users only",                             "require" => "valid-user"                    )                  ) }

Restart lighttpd:
# service lighttpd restart

Debugging Tip: Trace the Process and See What It is Doing with strace

Posted: 10 Apr 2008 06:22 AM CDT

strace is a useful diagnostic, instructional, and debugging tool. It can save lots of headache. System administrators, diagnosticians and trouble-shooters will find it invaluable for solving problems with programs for which the source is not readily available since they do not need to be recompiled in order to trace them. This is also useful to submit bug reports to open source developers.

Each line in the trace contains the system call name, followed by its arguments in parentheses and its return value.

Run strace against /bin/foo and capture its output to a text file in output.txt:
$ strace -o output.txt /bin/foo
You can strace the webserver process and see what it's doing. For example, strace php5 fastcgi process, enter:
$ strace -p 22254 -s 80 -o /tmp/debug.lighttpd.txt
To see only a trace of the open, read system calls, enter :
$ strace -e trace=open,read -p 22254 -s 80 -o debug.webserver.txt
Where,

-o filename : Write the trace output to the file filename rather than to screen (stderr).
-p PID : Attach to the process with the process ID pid and begin tracing. The trace may be terminated at any time by a keyboard interrupt signal (hit CTRL-C). strace will respond by detaching itself from the traced process(es) leaving it (them) to continue running. Multiple -p options can be used to attach to up to 32 processes in addition to command (which is optional if at least one -p option is given).
-s SIZE : Specify the maximum string size to print (the default is 32).

Refer to strace man page for more information:
$ man strace