Showing posts with label lt. Show all posts
Showing posts with label lt. Show all posts
2010-04-12
Linux processes
Finally got around to reworking the processes chapter (viewable in html now). Still need to add a section about screen and rework the labs for this chapter...
2010-02-16
Java jre performance (gcj vs Sun)
Generating a pdf from docbook xml using Apache fop like this:
But it takes 12-13 minutes on Debian inside Virtualbox on a Core 2 Duo ??
This difference too big to attribute to virtualization alone!!
fop uses java...
Let's try Java from Sun instead of java-gcj...
32 seconds!! What !? Yep, speed increase from 12-13 minutes to 32 seconds.
I double tested by putting the symlink back to java-gcj, it took 12'35" again!
I'm amazed ;-)
fop -xml $xmlfile -xsl $XSLFILE -pdf $pdffiletakes about 40 seconds on Debian on an old Pentium 4.
But it takes 12-13 minutes on Debian inside Virtualbox on a Core 2 Duo ??
This difference too big to attribute to virtualization alone!!
fop uses java...
paul@deb503:/usr/lib/jvm$ ls -l
total 4.0K
lrwxrwxrwx 1 root root 8 2010-01-15 22:51 default-java -> java-gcj
drwxr-xr-x 5 root root 4.0K 2009-10-28 14:16 java-1.5.0-gcj-4.3-1.5.0.0
lrwxrwxrwx 1 root root 26 2009-10-28 14:16 java-gcj -> java-1.5.0-gcj-4.3-1.5.0.0
Let's try Java from Sun instead of java-gcj...
paul@deb503:~/lt$ ls -l /usr/lib/jvm/
total 8.0K
lrwxrwxrwx 1 root root 14 2010-02-16 12:17 default-java -> java-1.5.0-sun
drwxr-xr-x 5 root root 4.0K 2009-10-28 14:16 java-1.5.0-gcj-4.3-1.5.0.0
lrwxrwxrwx 1 root root 23 2010-02-16 12:15 java-1.5.0-sun -> java-1.5.0-sun-1.5.0.17
drwxr-xr-x 6 root root 4.0K 2010-02-16 12:15 java-1.5.0-sun-1.5.0.17
lrwxrwxrwx 1 root root 26 2009-10-28 14:16 java-gcj -> java-1.5.0-gcj-4.3-1.5.0.0
32 seconds!! What !? Yep, speed increase from 12-13 minutes to 32 seconds.
I double tested by putting the symlink back to java-gcj, it took 12'35" again!
I'm amazed ;-)
2009-11-14
teaching Linux System Administration
Yes it has been a long time since the last blogpost. Yes linux-training.be needs a lot of updates. But it has been a busy couple of months ;-)
Here's a picture of three happy students who were very eager to learn about system administration (and fundamentals). They kept me teaching from nine till six!
Here's a picture of three happy students who were very eager to learn about system administration (and fundamentals). They kept me teaching from nine till six!
2009-05-27
Linux Training updates
Linux Training got a lot of updates the past two weeks (thank you financial crisis for giving me time).
Added an introduction to mysql (chapter 31 in LinuxTraining.pdf). (Can someone with mysql knowledge please review this ?)
Finally updated init and booting, they are two chapters now. Booting is chapter 17, init is chapter 18. The practices for these chapters are not done yet, and lilo could use a bit more info.
Notes to self:
- chapter 13 (more about bash) is dreadful, high priority!
- idem ditto for 22.scheduling and 24.memory management
By the way, there is really no point in putting old copies of this book online (like on scribd). The latest complete version can always be downloaded at www.linux-training.be.
Added an introduction to mysql (chapter 31 in LinuxTraining.pdf). (Can someone with mysql knowledge please review this ?)
Finally updated init and booting, they are two chapters now. Booting is chapter 17, init is chapter 18. The practices for these chapters are not done yet, and lilo could use a bit more info.
Notes to self:
- chapter 13 (more about bash) is dreadful, high priority!
- idem ditto for 22.scheduling and 24.memory management
By the way, there is really no point in putting old copies of this book online (like on scribd). The latest complete version can always be downloaded at www.linux-training.be.
2009-05-19
Where is /proc/bus/usb/devices ?
/proc/bus/usb/devices is still mentioned in the manpage of lsusb, but not existing on my current Ubuntu (2.6.24) and RHEL5 (2.6.18) system.
The /proc/bus/usb/ structure is however present on Debian (2.6.17), including the devices file.
Where does the lsusb command go to get usb device information ? Is it not reading /proc/bus/usb ? Is this a kernel change in 2.6.18 ?
root@laika:~# ls -al /proc/bus/usb/
total 0
dr-xr-xr-x 2 root root 0 2009-05-19 14:24 .
dr-xr-xr-x 6 root root 0 2009-05-19 10:15 ..
root@laika:~#
The /proc/bus/usb/ structure is however present on Debian (2.6.17), including the devices file.
Where does the lsusb command go to get usb device information ? Is it not reading /proc/bus/usb ? Is this a kernel change in 2.6.18 ?
2009-03-03
macro in vim question...
I can create a simple macro in vi(m) to add the letter b at the end of every line:
q b $ a b Esc j q
q start recording macro
b name the macro
$ jump to end of current line
a append
b the letter b
Esc back to command mode
j one line down
q end recording
When I have a text file, and I execute 20@b, then the letter b is added to 20 lines.
When there are less than 20 lines, then I would expect this macro to add multiple b's to the end of the last line. But it does not. When you type the commands in the macro yourself, then it does add multiple b's.
How can you explain this behaviour ?
Is there an easier way to add a b to every line (in vim) ?
q b $ a b Esc j q
q start recording macro
b name the macro
$ jump to end of current line
a append
b the letter b
Esc back to command mode
j one line down
q end recording
When I have a text file, and I execute 20@b, then the letter b is added to 20 lines.
When there are less than 20 lines, then I would expect this macro to add multiple b's to the end of the last line. But it does not. When you type the commands in the macro yourself, then it does add multiple b's.
How can you explain this behaviour ?
Is there an easier way to add a b to every line (in vim) ?
2009-01-20
2009
Today was a good day! Good contact with friends and neighbours, good health, nice girlfriend coming here tonight ;-)
Health
December 24th 2008 I was struck with vertigo caused by Neuritis Vestibularis (pdf in Dutch). I felt really really dizzy for about six hours, then the pills started working. I needed the pills every day for about a week. The dizziness is almost gone...but my balance still sucks.
Oh, and those Agyrax pills make you sleep all day AND all night! Scary...
Girlfriend
December 30th I was seduced by a very nice and good looking girl.
Blender
I bought a blender yesterday!!!! The SEB performa. Good choice!
Goal
It seems like I found a real goal. Make a good book... it still needs a lot of work, but it should be "good enough" by the end of 2009.
Health
December 24th 2008 I was struck with vertigo caused by Neuritis Vestibularis (pdf in Dutch). I felt really really dizzy for about six hours, then the pills started working. I needed the pills every day for about a week. The dizziness is almost gone...but my balance still sucks.
Oh, and those Agyrax pills make you sleep all day AND all night! Scary...
Girlfriend
December 30th I was seduced by a very nice and good looking girl.
Blender
I bought a blender yesterday!!!! The SEB performa. Good choice!
Goal
It seems like I found a real goal. Make a good book... it still needs a lot of work, but it should be "good enough" by the end of 2009.
2008-11-16
Linux Training
Made a little time today to work on my Linux course. Almost all corrections from reviewers are integrated (as a stack). Some of those corrections require me to learn a bit more ;-)
I've been teaching the Linux Fundamentals four times since September and (partly) integrated my experience in the course to make the pace flow nicer between theory, demo's and practices.
The thing is, I spent most of today (again) on the "first steps" chapter (pwd, cd, ...). I must not touch it again, unless for typo's! Other chapters require more urgent attention:
- I need to rewrite the two bash chapters, the first one is too long (imho it should be split in two separate chapters), the last one is way too brief.
- I also think the File System Hierarchy chapter is too long (too much theory compared to the humble practice)
- Processes is kinda complete, but the order and layout can improve (same for vi)
- Scripting is incomplete and also needs some order.
- The first chapter (introduction) is a mess. Luckily i teach it better than it is written.
The System Administration course is in even worse shape. I'm really not happy about it. Okay, maybe the hard disk and LVM chapters are good enough, but kernel compile is really lousy. (I have completely rewritten the kernel compile chapter, but only in my mind, not yet on paper.)
Anyway, thank you all for encouraging me and telling me it is a good book. No, this is not a plea for more pats on the back, just look at this post as my todo-list.
I hope to have updated the bash chapters and the kernel compile chapter RSN.
I've been teaching the Linux Fundamentals four times since September and (partly) integrated my experience in the course to make the pace flow nicer between theory, demo's and practices.
The thing is, I spent most of today (again) on the "first steps" chapter (pwd, cd, ...). I must not touch it again, unless for typo's! Other chapters require more urgent attention:
- I need to rewrite the two bash chapters, the first one is too long (imho it should be split in two separate chapters), the last one is way too brief.
- I also think the File System Hierarchy chapter is too long (too much theory compared to the humble practice)
- Processes is kinda complete, but the order and layout can improve (same for vi)
- Scripting is incomplete and also needs some order.
- The first chapter (introduction) is a mess. Luckily i teach it better than it is written.
The System Administration course is in even worse shape. I'm really not happy about it. Okay, maybe the hard disk and LVM chapters are good enough, but kernel compile is really lousy. (I have completely rewritten the kernel compile chapter, but only in my mind, not yet on paper.)
Anyway, thank you all for encouraging me and telling me it is a good book. No, this is not a plea for more pats on the back, just look at this post as my todo-list.
I hope to have updated the bash chapters and the kernel compile chapter RSN.
2008-08-25
Linux Training
Found some time again to work on linux-training.be. I reviewed the Linux Fundamentals book(pdf) (biggest changes are in chapter 9 permissions).
It is still not complete, but good enough at the moment. Imho it is missing chapters (or appendixes) about regular expressions, sed and awk (and maybe some more info about other commands like pr, expand, nl, fmt, join, ...).
I am also a bit annoyed because the processes chapter is in Fundamentals, I consider it a System Administration topic...but students almost always demand (and enjoy!) this chapter.
Many thanks to Wouter and Geert for the feedback, to Serge for hosting the svn and rss feed and to Inge for the cover design.
Time to tackle the System Administration book(pdf)...it needs a lot of work!
It is still not complete, but good enough at the moment. Imho it is missing chapters (or appendixes) about regular expressions, sed and awk (and maybe some more info about other commands like pr, expand, nl, fmt, join, ...).
I am also a bit annoyed because the processes chapter is in Fundamentals, I consider it a System Administration topic...but students almost always demand (and enjoy!) this chapter.
Many thanks to Wouter and Geert for the feedback, to Serge for hosting the svn and rss feed and to Inge for the cover design.
Time to tackle the System Administration book(pdf)...it needs a lot of work!
2008-07-19
Linux Training
Today i reviewed and updated (only minor changes) the "First Steps" chapter of our Linux Fundamentals course. This chapter is an introduction to commands to handle directories, files and file contents. Remember, this is for absolute beginners.
It would be nice if some Linux enthousiasts take a look at it (18 pages, 65kb pdf) and shoot some feedback in my direction (any suggestion and critics are welcome!).
The only 'issue' i have with this chapter is that it is organized by command... meaning it requires a teacher to also stress subjects like "tab completion" and "absolute and relative paths".
Thank you Ghosty and Wouter, one day all your much appreciated feedback will be included (i'm keeping your e-mails until job done!)
It would be nice if some Linux enthousiasts take a look at it (18 pages, 65kb pdf) and shoot some feedback in my direction (any suggestion and critics are welcome!).
The only 'issue' i have with this chapter is that it is organized by command... meaning it requires a teacher to also stress subjects like "tab completion" and "absolute and relative paths".
Thank you Ghosty and Wouter, one day all your much appreciated feedback will be included (i'm keeping your e-mails until job done!)
2008-07-12
Linux Training
Most of you know that i... woops sorry we are writing a Linux System Administration course. This week i expanded and re-organized the "Introduction to Users" chapter.
It would be really nice if some Linux enthousiasts take a look at it (11 pages, 53kb pdf) and shoot some feedback in my direction (any suggestion and critics are welcome!).
(i don't feel good about the sudo part, and i still need to rework the practice at the end of the chapter...)
EDIT: groups is the next chapter (3 page pdf)
It would be really nice if some Linux enthousiasts take a look at it (11 pages, 53kb pdf) and shoot some feedback in my direction (any suggestion and critics are welcome!).
(i don't feel good about the sudo part, and i still need to rework the practice at the end of the chapter...)
EDIT: groups is the next chapter (3 page pdf)
2008-03-31
Linux Training
Just put a new 'beta' version of my Linux System Administration course online. Making it public might improve my motivation to update it sooner rather than later ;-)
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