Now normally I do frequent saving to avoid such issues. But right now there is no Save Draft function so I rely on frequent saving to OpenOffice. It always works and I rarely have issues. This time, however, I did. When I un-iconified OpenOffice (I am using Elive-Compiz so applications minimize to icons) everything but he cursor and keyboard froze up tight. Or so I thought.What actually happened was that OpenOffice caused an issue keeping me from gaining access to any application. I could move the cursor but that was it. I couldn’t get a menu or interact with any applications.

What happened?

For those that are curious here is the output of my ~/.xsession-errors file:
window managed: 0xc0155b : 0x40abdc, 402
window managed: 0xc01576 : 0x40afed, 402
Unhandled property: 41 font
Unhandled property: 41 font
_e_container_cb_mouse_down
_e_container_cb_mouse_down
_e_container_cb_mouse_down
window managed: 0xc015dc : 0x14035fe, 402
act fn max
max parse: NONE
window managed: 0xc01637 : 0x1c0b86d, 402
_e_container_cb_mouse_down
efreet_desktop_new error: no Desktop Entry section
_e_container_cb_mouse_down
window managed: 0xc016f0 : 0x240000a, 402

After a bit of research it looks like it could be an autoraise error. That, of course, doesn’t mention how I got out of this situation. Let’s take a look.

How it worked out

Fortunately I had a good idea which application caused the problem. I assumed this because OpenOffice Writer was the last application I had any interaction with. Even if it wasn’t OpenOffice I had the following applications open that could have possibly caused the problem.

• Claws Mail
• Firefox
• Rhythmbox
• GnuCash
• xterm

I had to hope that the issue wasn’t Firefox, because that was the data I really needed to save. So, with my list in hand I hopped over to a virtual console to see if I could get lucky.

Getting to a virtual console

Virtual consoles allow you to, effectively, have more than one user logged in. Or you could have the same user logged in with one instance being a graphical desktop and the other a command line desktop. To get to different virtual desktops you enter the Ctrl-Alt-F*keys (Where * is 1-0). When I got to the virtual console I logged in with the my standard user information and was greeted with my bash prompt. Since I assumed the culprit was OpenOffice writer I wanted to get the PID of this application so I issued the command:

ps aux | grep soffice

Which gave the proper PID for the currently running command soffice -writer. The next step was to issue the kill command on the PID like so:

kill PID

Where PID is the actual PID given to me by the ps command above.

When the process was killed I then hopped back to my original console (in my case it was Ctrl-Alt-F7) and, lo and behold, I had regained control of my desktop. I could then re-open OpenOffice, save my work, finish my article, and submit.

Bullet Doged.

Final thoughts

Yes this whole situation could have been avoided with a working Save Draft feature, but that is not available yet. I could have also been using a different desktop. The “what ifs” could go on and on. But ultimately these things happen and it’s always nice to know you have the means to solve the problem, even if you have to get creative to do so.

You will be glad to know that the ps command will most certainly be already installed on your Linux machine, so there is no need to worry about installation.

Command structure

The basic command structure for ps is:

ps OPTION

Of course every good Linux command offers a lot of options, and ps is no exception. For this command we will just outline the best groupings of options together instead of just listing all of (or the best) options. This way you can skip right down to the command you need to use.

Show list of processes owned by a specific user

Say I want to list all processes owned by user jlwallen. To do this I could enter one of two commands:

ps ux

This will list out all processes that are owned by the user issuing the command. The results for this command will look like:

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
jlwallen   560  0.0  0.3  18312  7376 ?        SNs  19:40   0:00 /etc/alternativ
jlwallen   561  0.0  0.1   7316  3932 pts/0    SNs  19:40   0:00 bash
jlwallen  1137  0.0  0.0   1644   416 ?        S    19:47   0:00 sleep 8
jlwallen  1141  0.0  0.0   1644   420 ?        S    19:47   0:00 sleep 8
jlwallen  1142  0.0  0.0   4384  1012 pts/0    RN+  19:48   0:00 ps ux

You can also get a similar listing with the command:

ps U jlwallen

The results of this command will be:

PID TTY      STAT   TIME COMMAND
560 ?        SNs    0:00 /etc/alternatives/x-terminal-emulator
561 pts/0    SNs    0:00 bash
1223 ?        S      0:00 sleep 8
1227 ?        S      0:00 sleep 8
1228 pts/0    RN+    0:00 ps U jlwallen

Show all processes

To see every process on your system you would enter the command:

ps aux

The results of this command would look similar to that of ps ux only it would show the process of every user as well as the system.

List the details of a single process

What about when you want to see the details of only a single process? Imagine issuing the command ps ux and having to search through all of the listings to find the information about the one process you are trying to gain information about. Say, for example, you need to find the PID (Process ID) of the currently running daemon for Dansguardian. You can use the ps command and pipe the results to the grep command to search the listing for a specific string and print out only the matching strings. To do this issue the command:

ps aux | grep dansguardian

which will print out something like:

113       2596  0.0  0.5  17852 11460 ?        Ss   06:49   0:00 /usr/sbin/dansguardian

Now you can see the PID of Dansguardian is 2596. You can kill this with the kill 2956 command.

Final thoughts

There are many more uses for the ps command as well as many more ways to use the ps command. The above three examples are the most often used, but don’t think you are limited to only those uses. Issue the command man ps and you will see a full listing of all the ps options available to you.

Although you might think this a system of process management that should be avoided by the new user, you should consider that there may be times when knowing this process can really save your skin. So, although you may tend to shy away from the command line tools, this would be one of those that is good to know in a pinch.

The Commands

The first thing you have to understand is the commands you will be using. There are two commands that are useful: kill and killall. The kill command is used in conjunction with a process ID (PID) and the killall command is used in conjunction with command names. Your first reaction is most likely “How do I get the PID of an application?” Well, that will take another command.

Learn By Example

Let’s use Firefox as an example. Say, for some reason, Firefox has frozen and you can not get it to respond. Open up a terminal and issue the command killall firefox if that doesn’t kill Firefox then Firefox was started with a different command. To find out what that command is you could employ the ps command like so:

ps aux|grep firefox

The output would look something like:
[jlwallen ~]$ ps aux|grep firefox
jlwallen 10199  3.8 28.8 417396 223764 ? RNsl Feb23  77:22 /usr/lib/mozilla/firefox-bin -a firefox
jlwallen 13434  0.0  0.0   3796   688 pts/0  RN+  20:14   0:00 grep firefox

You see the line that includes firefox-bin? That is most like what you need to kill. So issue the command killall firefox-bin and the frozen Firefox will go away.

If you look up at the command output again you can see the output includes the PID of each command. The PID associated with firefox-bin would be 10199. You could issue the command kill 10199 and Firefox would close as well.

Frozen X

What if X Windows freezes and you know the culprit was, say, Evolution? You can’t get to a terminal window so what do you do? You have to go to a different virtual console. To do this you will hit the key combination Ctrl-Alt-F* (Where * is a number 1-9. This number will differ depending upon which virtual console X is running.) Once you are in a virtual consol you will have to log in as your user and then issue the kill command. You can then go back to the virtual console running X and, hopefully, it will be back under your control.

Final Thoughts

It’s not as user-friendly as either the GNOME or KDE tools, but this method is a very valuable method of process control. Some day you will need to have this method in your tool belt and, when you do, you’ll be glad you have it.