Notes on ScopePort

I have been searching for a good GNOME LaTeX editor for a long time after i switched from KDE to GNOME. (My KDE favorite was Kile). I tested some andcame to the result that Texmaker is the best LaTeX editor that does not require the KDE libraries (even though it is based on QT)

Writing LaTeX with vim is also okay but I like to just press F6 and get the generated PDF file opened in my favorite PDF viewer.

When a gem installation fails with something like “extconf.rb:1:in `require’: no such file to load” you are probably missing the ruby development packages.

On Ubuntu you can fix this by installing the ruby1.8-dev package. (sudo aptitude install ruby1.8-dev)

All you need is the ImageMagick tool “mogrify”:

lennart@sundaysister:~$ mogrify -strip *.JPG

Disturbing image material appeared when the Large Hadron Collider at the CERN was about to be fired up the first time. Reddit immediately pulled out all the stops and sent Gordon the equipment he needed to fight the head crabs that would appear after the LHC startup.

These days his equipment arrived at the CERN! Thank you reddit. (Oh. And also for all your referers!)

No, really. Every research organisation should be more like the CERN. You could make all of us nerds happy!

Sometimes it is not easy to find out what process is currently slowing down your system or why the mouse is jumping over the screen when it is supposed to follow your hand movements in a kind of gliding motion. I have collected a list of tools to find out what processes consume the most of your resources and even how to get an indication of the reason for that.

CPU and memory usage: top/htop

Most of you may already know “top”. It is the first program to fire up if the system gets unsually slow. top shows you a list of processes – ordered by their memory and CPU usage.

/usr/bin/top

As an alternative there is an improved version of top: htop. It has many more options for sorting, searching or display and shows the general system usage in a clearly arranged way.

/usr/bin/htop

htop might not be a standard part of your distribution but it should be available in the repositories.

I/O usage: iotop

Sometimes programs slow down the system by using too much I/O resources (e.g. when extracting a really big tarball). When the programs don’t need much CPU resources for heavy I/O resources they might now show up in top or htop. If you want to find out e.g. what is currently hammering your hard disk buffers you can take a look at iotop: It displays processes sorted by I/O usage in a top-like way.

/usr/bin/iotop

iotop might not be a standard part of your distribution but it should be available in the repositories.

MySQL and Apache

Sometimes you want to know what consumes most of your MySQL or Apache resources.

If you want to know what queries are currently executed and in what state the operation is you can use the “SHOW PROCESSLIST;” SQL command in a MySQL shell:

SHOW PROCESSLIST;

If your Apache has heavy load you might want to know what requests/files cause this load. There is a program “apachetop” that provides this information:

/usr/bin/apachetop

apachetop might not be a standard part of your distribution but it should be available in the repositories.

Finding out more about rioting processes

So you found the process that consumes the resources? Here is the ultimate solution to find out more about the process: /bin/lsof (list open files)

Here are the possibly most useful lsof modes:

Show all open files of the process with given PID: lsof -p [PID]
Show all programs that have currently opened a file: lsof [file]
Show all programs that have currently opened a file in a given directory: lsof +D [directory]
Show all programs that have a socket related to a given port: lsof -i :[port]

lsof -p 3773

/bin/lsof +D /var/log

/bin/lsof -i :12200

If you use Fedora with PulseAudio and have the problem that you don’t get sound in Flash (SWF) your system might be missing the “libflashsupport” package.

yum install libflashsupport

In my case the audio channel of the Youtube video was flickering in the Pulse Audio control and there was no sound at all.