Saturday, November 26, 2011

Protect your root account.

I will present a solution to protect the root account, quite funny but still elegant.
You can read about the command trap using: man trap.
What is this command?
when the specified event will occur will execute the command specified.
In this case, it will receive signal respectively will execute one command - exit
The source code.
 protect()
 {
 echo "What is the secret ?"
 trap protect 2 20
 read -s resp
 if [ "$resp" != "asd" ]; then
 echo "Error!"
exit
fi
 }
 protect
The result will be leaving the root account if you do not answer the question correctly.
Now protect the file against unauthorized changes:
# chmod 700 /root/.bashrc
You can create using the example above, different ways to execute various commands.

Monday, September 26, 2011

Android ARM Assembly by Vikram Aggarwal

Today I read an interesting article about Android.
The article is written by the developers Vikram Aggarwal, a software engineer at Google.
This article - tutorial consists of a series on learning ARM assembly on Android.
Its subject is "...calling Assembly code from Android applications".
The tutorial contains the necessary source code and details for the reader to understand how it works.
For those who have never used Gas (GNU Assembler), this article is of interest much.
I wonder if there is anyone interested in the Fedora community to write Android applications.
This article can be read here.

Saturday, September 24, 2011

Creating folders and documents with gdata module

Today I played with gdata python module.
The problem that I solved it:
creating folders and documents in your Gmail account.
First, you need to install the gdata module.
In fedora I used:
yum install python-gdata.noarch 
Here are the first lines of source code that creates a folder named test-fedora
Python 2.7.1 (r271:86832, Apr 12 2011, 16:16:18) 
[GCC 4.6.0 20110331 (Red Hat 4.6.0-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import gdata.docs.service
>>> my=gdata.docs.service.DocsService()
>>> my.ClientLogin('your-account@gmail.com','your-password')
>>> my.CreateFolder('test-fedora')
I tried to automate the process of creating folders and I used a list and instruction for
>>> folders=['aaa','bbb','ccc']
>>> for f in folders:
...     my.CreateFolder(f)
... 
To create a document to write more lines of code.
This is because there are many types of documents
>>> new_entry = gdata.GDataEntry()
>>> new_entry.title = gdata.atom.Title(text='fedora-test')
>>> category = my._MakeKindCategory(gdata.docs.service.DOCUMENT_LABEL)
>>> new_entry.category.append(category)
>>> created_entry = my.Post(new_entry, '/feeds/documents/private/full')
Here's a simple solution to avoid loss of mail password.
>>> import getpass
>>> username = raw_input('Please enter your username: ')
Please enter your username: user1
>>> password = getpass.getpass()
Password: 
>>> print username
user1
>>> print password
pass1
I hope you will use this

Thursday, September 15, 2011

The list of linux tutorials ...

The last time I wrote small tutorial for free-tutorials.org site.
These tutorials have covered several areas.
Here are targeting Linux.
The indication of a denial of service (DoS) attack...
How to display memory in real time on Linux system...
Change settings and passwords in Windows using Lin...
How to change bash custom prompt ?
How to use the import command to take screenshots?
Linux commands : "find" and the option "empty"
Create html file with bash script.
Simple bash script to create folders, files and im...
Using wget tool
error: dd: opening `/dev/sdb1': Permission denied...
error: 'memset' was not declared in this scope
Installing and configuring the Eclipse IDE - Googl...
How to set up an external webrowser on Eclipse IDE
Fedora - Install Skype
Modifying shortcuts keys on Bluefish 1.0.7
Fedora - How we can get movies from youtube.
Fedora 12 - How can we run one script when system ...
Linux Text-To-Speech Tutorial
Geany and regular expressions.
Yumex on Fedora
Assign keys on Linux.

I will try to write more tutorials about Linux...

Saturday, September 10, 2011

Fedora 15 : Extracting rar files

The unrar package can be installed from here.
The unRAR utility is a freeware program, distributed with source code and developed for extracting, testing and viewing the contents of archives created with the RAR archiver version 1.50 and above.

unrar-3.9.9-1.fc15.x86_64.rpm  
unrar-3.9.9-1.fc15.i686.rpm  
unrar-3.9.9-1.src.rpm  
unrar.spec

$ unrar

UNRAR 3.92 freeware      Copyright (c) 1993-2010 Alexander Roshal

Usage:     unrar  - -  
               <@listfiles...> 


  e             Extract files to current directory
  l[t,b]        List archive [technical, bare]
  p             Print file to stdout
  t             Test archive files
  v[t,b]        Verbosely list archive [technical,bare]
  x             Extract files with full path


  -             Stop switches scanning
  ad            Append archive name to destination path
  ai            Ignore file attributes
  ap      Set path inside archive
  c-            Disable comments show
  cfg-          Disable read configuration
  cl            Convert names to lower case
  cu            Convert names to upper case
  dh            Open shared files
  ep            Exclude paths from names
  ep3           Expand paths to full including the drive letter
  f             Freshen files
  id[c,d,p,q]   Disable messages
  ierr          Send all messages to stderr
  inul          Disable all messages
  kb            Keep broken extracted files
  n       Include only specified file
  n@            Read file names to include from stdin
  n@      Include files listed in specified list file
  o[+|-]        Set the overwrite mode
  or            Rename files automatically
  ow            Save or restore file owner and group
  p[password]   Set password
  p-            Do not query password
  r             Recurse subdirectories
  sl      Process files with size less than specified
  sm      Process files with size more than specified
  ta      Process files modified after  in YYYYMMDDHHMMSS format
  tb      Process files modified before  in YYYYMMDDHHMMSS format
  tn
Works well.

Thursday, June 16, 2011

Firefox sync - sinking ?

Today I tried to use Firefox Sync.
I do not remember if I had a user account, but I tried to make a password reset.
I do not know if the same thing happens on Windows, but on Fedora, I received a strange thing output.
I assumed that it is a cookie, but it is not normal.
Maybe someone can tell what it is ...
Here's the picture with this strange number:

Friday, June 3, 2011

The myth of drop_caches

I will try to clarify the myth about drop_caches.
This along with other settings can be made in the folder: /proc/sys/vm/
First, the files in this directory can be used to tune the operation
of the virtual memory (VM) subsystem of the Linux kernel and also to
write out of dirty data to disk.
About drop_caches we can say that is only one of the options and not only make
causes the kernel to drop clean caches, and entries inodes from memory,
the result causing that memory to become free.
We have three basic options :
  • to free pagecache: echo 1 > /proc/sys/vm/drop_caches
  • to free dentries and inodes: echo 2 > /proc/sys/vm/drop_caches
  • to free pagecache, dentries and inodes: echo 3 > /proc/sys/vm/drop_caches
Note that user should run sync first.
What happens then?
The answer is also simple and clear.
If you drop the cache than the CPU load goes up. This happens because the cache is gone.
Also, available RAM goes up because the cache is empty.
Logical, the performance will suffer because you are not taking advantage of the cache.
Then over time, the caches will fill and this is a good thing if you don't instruct Linux to drop the caches.

In reality, dropping caches has a little positive effect on performance, but in fact, it tends to have a negative effect in long-term.
I hope I have correctly understood and explained, so if you think it is not, I wait for your feedback.

Fighting Blender, NVIDIA and GNOME ...

Today I spent some time with Blender, NVIDIA and GNOME ...
Since I did pre-update and put Fedora 15, the system worked well until today.
Today I tried to relax a bit with Blender 3D, but ...
[free-tutorials@user ~]$blender
Info: Config directory with "startup.blend" file not found.
Segmentation fault (core dumped)
How to prevent uploading that file? Simply using:
[free-tutorials@user ~]$blender --factory-startup 
Segmentation fault (core dumped)
Obviously, I should try to debug:
[free-tutorials@user ~]$blender --factory-startup  -d
Blender 2.57 (sub 0)
Build: 2011-04-27 16:56:56 Linux:32bit Release
argv[0] = blender
argv[1] = --factory-startup
argv[2] = -d
read file 
  Version 256 sub 6 svn r36063

ordered
 OBCube
 OBLamp
 OBCamera
Segmentation fault (core dumped)
Simply don't want, it's something related to graphics card ...
[free-tutorials@user ~]$blender --factory-startup  -d -noglsl 
Blender 2.57 (sub 0)
Build: 2011-04-27 16:56:56 Linux:32bit Release
argv[0] = blender
argv[1] = --factory-startup
argv[2] = -d
argv[3] = -noglsl
read file 
  Version 256 sub 6 svn r36063

ordered
 OBCube
 OBLamp
 OBCamera
Segmentation fault (core dumped)
So the problem is not related to GLSL.
Then I tried to see what glxinfo says.
[free-tutorials@user ~]$glxinfo | grep Error
Error: glXCreateContext failed
I found this problem and I added to xorg.conf the following lines of code.
Section "Files"
ModulePath "/usr/lib/xorg/modules/extensions/nvidia"
ModulePath "/usr/lib/xorg/modules/drivers"
ModulePath "/usr/lib/xorg/modules"
EndSection 
I must admit that after restarting the computer, greeted me with the gnome interface and unprecedented special effects.
Then I waited ... and waited ... I fixed up with a simple line of code:
$  gsettings set org.gnome.desktop.session session-name 'gnome-fallback'
... written in Xfce terminal, because in gnome I have not succeeded.
Now I have the old gnome, slightly improved but it works flawlessly with Blender 3D...

Thursday, April 21, 2011

News: "A tour of Eclipse Helios" by IBM

It's a pretty good and complete information about Helios ...
Article begins:
Helios is the simultaneous release of 39 Eclipse projects. In terms of statistics, the Helios release includes 33 million lines of code developed by about 500 Eclipse.org committers from 44 companies...
You can read here and you will be impressed by the new Helios.
The best part for Linux users is Linux tools.
As Andrew Overholt says in the same article:
"The Linux Tools project also aims to increase the amount of Eclipse technology available in Linux distributions. We are working towards this goal by providing a build harness of the Eclipse SDK that is easy to consume for Linux distributions and already have a number of distribution consumers."
I have not yet found the negative aspects from the Helios ...

Friday, April 15, 2011

What things should be fixed quickly ?

Here are some things that should be repaired.
There are minor things or less, but make life a misery. There are things that generate more questions and more errors on the Internet.
This is an epidemic of questions there just because they are not repaired.

1. Google must give the possibility to download video files updated...
2. Python modules gdata do not work for all versions... ( and many modules has the same problem)
3. Python module ftplib does not know about SFTP, just FTP
4. Too many compilers for C and C + + and lack of advanced tutorials for setting them, especially gcc on windows
5. Social networks Spam filling our mail.


I will try to update the list over time.
I'm sure there are more ...

Monday, March 21, 2011

The word "includ" generates error in gmail.

I accidentally discovered an error.
I sent feedback to Google, I hope to resolve quickly.
The problem is with the word "include" is a word used in the Romanian language and means "include".
Because of this, I can not send emails it contains, Gmail asking to "include file"

The discovery of an ancient ancestors linux ...

Who says penguins are weak?
Linux is a good system if it is used by smart people.
Since ancient times people are born with penguins.
It seems that dinosaurs could not survive, but the Penguins have managed well.
They became smaller but everyone loves them.
Whether they are small and fast as Gentoo, or slower ... we are glad that we have no windows open.
More info here.