ECHO-tutorials.blogspot.com

Arithmetic equations in bash

2012-03-28T07:37:00.000-07:00

Basic equations in bash scripts:

x=15
y=8
sum=$((x+y))

dif=$((x-y))

mod=$((x%y))

prod=$((x*y))

How to search a word in multiple files

2012-03-06T07:01:00.000-08:00

1. Search a word in all the files with the .txt extension in current directory.

 grep -H "word" *.txt

2. Search a word in all the files in current directory and its subdirectories.

grep -H -r "word" home/directory

-H = display the name of the file
-r = search recursively trough subdirectories

How to remove/replace a given character/word from all the filenames in current directory using sed

2012-02-24T07:43:00.004-08:00

#!/bin/bash

extension="txt"

for files in *.$extension; 

do

    mv $files `echo $files | sed 's/B/A/g'`; 

done;

The mv command is used to rename the files.

sed parses the filename and replaces all the occurrences of "B" character with "A".

eg. BAOBAB.txt will be replaced by AAOAAA.txt

The script is case sensitive. Also, be careful with special characters that need to be escaped with "\".
For example if you have a file called ^name.txt and want to replace "^" character from the filename with "A", using the command:

mv $files `echo $files | sed 's/^/A/g'`;  

will lead to the following output:

A^name.txt

You need to escape "^" character:

mv $files `echo $files | sed 's/\^/A/g'`;

In this case the output will be:

Aname.txt

This script also works if you use words instead of characters.

Install Xara Xtreme on Ubuntu 10.04

2012-02-13T04:12:00.002-08:00

Xara Xtreme is a leading-edge graphic tool, easy-to-use and one of the world's best free graphics program.

Xara Xtreme is supplied in autopackage format. Follow the next steps to install the program:

Download the Xara Xtreme Linux installation package (http://www.xaraxtreme.org)
Make this package executable:
- Click on "Properties".
- Click on the "Permissions" tab.
- Ensure the checkbox "Allow executing file as program" is checked.
- Click on "Close".
Double click on .package file
The installer will begin by prompting you whether to download the autopackage code (if autopackage is not already installed). Answer yes (or simply press Enter).
After some time, it will display a window asking for the administrator (sudo) password. This is to install autopackage system-wide.
After autopackage has finished installing, Xara installation will begin. You may be prompted for the password again.
When Xara has finished installing, you should have a Xara icon in your application menu (e.g. Applications > Graphics > Xara Xtreme)

Download autopackage archive from

How to install applications in Ubuntu?

2010-06-05T08:21:00.001-07:00

There are multiple ways to install applications in Linux:

1. From the command line

Run: sudo apt-get install app_name

If app_name files are ported for the Linux distribution (Ubuntu, Fedora, etc) and are available then it will download and install all the files automatically.

2. Trough a graphical package management tool
If you are not comfortable using the command line, you can use many graphical front-end tools for Apt.
Ubuntu
Add new applications

Applications menu → Ubuntu Software Center → Get Software

Remove installed applications

Applications menu → Ubuntu Software Center → Installed Software

→ Select application → Remove

RedHat
Start → System Settings → Add/Remove Applications

3. Autopackage

Autopackage has been developed keeping in mind the functionality of MS Windows installers, Autopackage is software that lets you create binary packages of software for Linux that will install automatically, interactively on any Linux distribution through multiple front-end. When the Autopackage installer file is run to install a certain software, it checks the system for the installed component the software in question needs, installs it if it finds in its installer files or downloads and installs it from internet (similar as Debian’s Apt) if it does not find it locally. This concept is in infant stage, and you can find a few applications Autopackaged already.

Source: http://raviratlami1.blogspot.com

4. From a source file

The best way to install an application in Linux is to compile its source. Linux sources are available as compressed tar gzipped or bzipped files. To install application through its source, copy or download the source in a directory you think appropriate and then decompress them. For example, if you have source file in tar gzipped format, say, source file of package xyz, xyz-3.29.tar.gz, then the command to unpack it will be:

tar -zxvf xyz-3.29.tar.gz

The command will create a directory containing all the source files called xyz-3.29 in current directory. Now change to this directory and see the directory listing. You will find many files and directories there. You will also find a script file called configure. Now give the following command:

./configure

If you had installed necessary development environment including compilers, make, automake tools in your computer, then it will start compiling necessary information and creating necessary make files. If this command finishes without errors then give next command:

make

This command should also finish without any error massage. Finally, change to root user mode by giving su command if you are not already in super user mode, and then give following command to install executable files at appropriate directories:

make install

Don't forget to give following command to remove unnecessary files created by above commands:

make clean

If you think every thing has gone right, then you can run the application by giving its name as command (in general), here, xyz. In some cases you may find program menu entries automatically added, else you have to add them manually.
Source: http://raviratlami1.blogspot.com

You need administrative access to Add/Remove Programs.

Linux Usefull Applications

2010-06-05T08:12:00.001-07:00

Here there are some of the best Linux applications:

1. Work with files (File Managers)
- NC style: Midnight Commander (mc)
- Windows Commander style: Krusader
- Windows style: Konqueror
- Text editors: Kedit, Gedit
2. Multimedia
- Music/mp3/ogg players: Rhythmbox Music Player, Mplayer, Winamp
- Video / mpeg4 players: Mplayer, Kplayer
- Audio editors: Ardour, Audacity
- Programs for CD/DVD burning with GUI: K3b Support: k3b.org
- Graphic files viewer: Xnview download from: xnview.com, GQView
- Simple graphic editors: OpenOffice.org Drawing, Xpaint
- Drawing program for children: Tuxpaint
- Powerful graphic editors in PhotoShop style: Gimp, ImageMagick
- Program for work with vector graphics: Inkscape
- 3D-graphics: Maya, Blender
3. Office/business
- Office suite: OpenOffice download from: openoffice.org
- Graphing / charting data: Kivio, Dia
4. Programming and development
- IDE: CodeForge, Eclipse
- C++ IDE: gcc
- Assembler: NASM
- Disassembler: Code source is open, Idasm
- Java IDE: NetBeans, Eclipse
- FTP-server: pure-ftpd, vsftpd, ftp
- Language for Web-development: PHP, Perl, ASP (module for Apache)
- Database engine: MySQL, PostgresSQL, Freebird
5. Scientific and special programs
- Math system in Matlab style: Matlab
- Math system in Mathematica style: Maxima
- Equation/math editor: OpenOffice Math

The applications are free and in order to install them you need to run the following command in the terminal:

sudo apt-get install application name

Tux

2010-06-04T09:31:00.003-07:00

Linus Torvalds personal mascot is a penguin nicknamed Tux, which has been widely adopted by the Linux community as the mascot of the Linux kernel. The first person to call the penguin Tux was James Hughes, who said that it stood for "(T)orvalds (U)ni(X)".

Source: wikipedia.org

Who is Linus Torvalds?

2010-06-04T09:21:00.001-07:00

Linus Torvalds, the creator of the Linux kernel, was born in Helsinki, Finland, on December 28, 1969. When Linus was ten years old, his grandfather, a statistics professor at University of Helsinki, purchased a Commodore VIC-20 computer. Linus served as an assistant to his grandfather by entering data into his grandfather's "programmable calculator" and, just for fun, taught himself some simple BASIC programs by reading the instruction books that came with the computer. By the time he registered as a computer science student at the University of Helsinki, Linus Torvalds was an accomplished programmer.

In 1991, after taking a course in Unix and C, Torvalds bought his own PC. He was unhappy with the operating system that came with the computer (MS-DOS) and decided to write his own. Torvalds became interested in Minix, a small Unix-like operating system developed for educational purposes by Andrew S. Tanenbaum, a Dutch professor who wanted to teach his students the inner workings of a real operating system. Minix was designed to run on Intel 8086 microprocessors and had source code that was readily available for study. Torvalds decided to develop an operating system that exceeded the Minix standards. He called it Linux, a contraction for Linus' Minix.

Linus Torvalds did not copyright his computer code. Instead, he published his code on the Internet and asked members of the comp.os.minix newsgroup to help him build his operating system. On August 25, 1991, Linus Torvalds posted this famous message:

Hello everybody out there using minix -

I'm doing a (free) operating system

(just a hobby, won't be big and professional

like gnu) for 386(486) AT clones.

Linus Torvalds credits much of the success of his operating system to the Internet and to Richard Stallman's GNU project. Torvalds and his co-developers made use of the system components developed by members of the Free Software Foundation for the GNU project. The open-source philosophy behind the development of Linux, combined with the success of the operating system, has made Linus Torvalds into what can arguably be called a "cult figure." Unlike Windows and other proprietary operating systems, Linux remains publicly open and extendible by contributers. Anyone can use it without charge as long as any improvements they make are not copyrighted and remain freely available. At present, it's estimated that only 2% of Linux code today was written by Linus Torvalds himself, although he still "owns" the Linux kernel (the central part of the operating system) and remains the ultimate judge of what new code and innovations are incorporated into it.

After spending 10 years as a student and researcher at the University of Helsinki coordinating the development of the Linux kernel, Linus Torvalds accepted a job with Transmeta, a Silicon Valley start-up company known for its recruitment of high profile talent and its Crusoe chip. He is married and has two daughters.

Source: wikipedia.org, searchenterpriselinux.techtarget.com

What is Linux?

2010-06-04T08:54:00.001-07:00

LINUX is a Unix-like operating system that was designed to provide personal computer users a free or very low-cost operating system comparable to traditional and usually more expensive Unix systems. Linux has a reputation as a very efficient and fast-performing system.

LINUX's kernel (the central part of the operating system) was developed by Linus Torvalds (1991) at the University of Helsinki in Finland. To complete the operating system, Torvalds and other team members made use of system components developed by members of the Free Software Foundation for the GNU Project.

Typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License.

Why Linux?

→ Free

→ Forget about viruses

→ Stable OS

→ Flexibility

→ Multitasking

→ Command line

→ Full access

→ Remote tasking ("real networking")

→ Multiuser

→ Access to shell, programming languages, databases, open-source projects

→ Better performance

→ More up-to-date

→ Open-source, publicly open and extendible by contributors

LINUX distributions: Ubuntu, Fedora, Mandriva, SuSE, etc.

Sources: wikipedia.org, searchenterpriselinux.techtarget.com

Setup the Proxy Server for apt-get in Linux

2010-06-04T06:46:00.006-07:00

Open a new root terminal and run the next command from $HOME folder:

gedit .bashrc

This will open the /etc/bash.bashrc file for editing. Add the following lines to the end of this file:

export http_proxy=http://user:password@my.proxy.server:port/ export ftp_proxy=http://user:password@my.proxy.server:port/

If you have no authentication on the proxy server, include only the server and port:

export http_proxy=http://cache.proxy.server:port/ export ftp_proxy=http://cache.proxy.server:port/

Finally, run the source command:

source .bashrc

Now you should be able to run apt-get from the command line.

Usefull Linux Shortcuts

2010-06-03T05:51:00.001-07:00

1.   CTRL+ALT+T = Run a terminal.
2.   CTRL+L = Clear the terminal.
3. CTRL+C = Stops the program (end task).
4. CTRL+Z = Send the current process to background. It is useful if you you need the terminal for awhile but don’t want to exit the running program completely. To get the process back type the command fg.
5.   ALT+[F9 or F10] = Minimize/Maximize a window.
6.   TAB = Start typing the command, filename, or directory and hit tab. Bash will automatically complete what you are typing.
7.   CTRL+ALT+[LEFT, RIGHT, UP, DOWN] ARROW = go to [LEFT, RIGHT, UP, DOWN] desktop.
8.   CTRL+U = Erase the current line.
9.   Ctrl + [a or e] = Move the cursor to the beginning/end of the current line.
10. Ctrl + Alt + Backspace = Kill the X server if X crashes and you can’t exit it normally.

Comenzi utile Linux

2010-06-03T05:45:00.001-07:00

man (command)= info (command)
w = display user list
pwd = print working directory
mkdir = create new folder
ls display files
xrandr = screen resolution
touch = create file
ps = see all processes
echo = display message on screen

NS2 allinone 2.34 install on Ubuntu 10.04

2010-06-03T04:31:00.001-07:00

1. Download ns-allinone-2.34.tar.gz from isi.edu
2. tar -xzvf ns-allinone-2.34.tar.gz to unpack the saved archive
3. cd ns-allinone-2.34
4. sudo apt-get install build-essential autoconf automake libxmu-dev
5. sudo apt-get install g++-4.3
7. cd otcl-1.13
8. gedit Makefile.in → Replace CC= @CC@ with CC=gcc-4.3 → Save
9. cd .. → ns-allinone-2.34
10. ./install
11. gedit ~/.bashrc → Add the following lines to the end of the file and specify the folder wher ns-allinone-2.34 was unpacked as /your/path (eg. /home/dan):

    # LD_LIBRARY_PATH

OTCL_LIB=/your/path/ns-allinone-2.34/otcl-1.13

NS2_LIB=/your/path/ns-allinone-2.34/lib

X11_LIB=/usr/X11R6/lib

USR_LOCAL_LIB=/usr/local/lib

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$OTCL_LIB:$NS2_LIB:$X11_LIB:

$USR_LOCAL_LIB

# TCL_LIBRARY

TCL_LIB=/your/path/ns-allinone-2.34/tcl8.4.18/library

USR_LIB=/usr/lib

export TCL_LIBRARY=$TCL_LIB:$USR_LIB

# PATH

XGRAPH=/your/path/ns-allinone-2.34/bin:/your/path/ns-allinone-

2.34/tcl8.4.18/unix:/your/path/ns-allinone-2.34/tk8.4.18/unix

NS=/your/path/ns-allinone-2.34/ns-2.34/

NAM=/your/path/ns-allinone-2.34/nam-1.14/

PATH=$PATH:$XGRAPH:$NS:$NAM

12.

source ~/.bashrc

13. ns → % exit

14.   cd ns-2.34

15.   ./validate

Installation complete.