Samet Kilictas’s Blog

Tag: Linux

Bash Shell Scripting Tutorial

by Samet Kilictas on Apr.30, 2010, under General, HowTo, Linux

Basics
This tutorial assumes that you already know how to log in to your UNIX machine, bring up the bash shell, and run basic commands such as ls and cat. Getting to this point is fairly easy, but unfortunately this is the level that most users stay at indefinitely. This tutorial is intended to help you start to learn the more advanced features of using a shell, and specifically bash, one of the most powerful shells available.

Please note that most of the command themselves are not explained; you can examine their functionality yourself by either reading their man page, or just experimenting with them to see what they do.

Redirection
Normally programs take input from our keyboard, and display the output to our screens. However, these are just the defaults – UNIX has the ability to redirect the input (commonly referred to as stdin, short for standard input) and output (commonly referred to as stdout, short for standard output).

Here is a simple example: the cat command displays the contents of a file to the screen. But we can redirect those contents to a file using the redirection operator ‘>’, like so:

$ cat myfile.txt
This is the contents of the file myfile.txt
$ cat myfile.txt > newfile.txt
$ cat newfile.txt
This is the contents of the file myfile.txt
$

In effect, we’ve made cat do the same thing as cp, by redirecting the output from the screen to a file. This isn’t terribly useful, but consider another, similar, scenario: cat can take multiple arguments, and it will display the files one after the other. This can be used to append one file onto another and create a new, combined file.

$ cat file1.txt
The quick brown fox...
$ cat file2.txt
...jumped over the lazy dog.
$ cat file1.txt file2.txt > combined.txt
$ cat combined.txt
The quick brown fox...
...jumped over the lazy dog.

Neat, eh?

We can also redirect the input, so that a program takes the contents of a file as if it were typed at your keyboard. cat doesn’t take any input, so let’s use bc, a command line calculator. Normally, you run the program, and it lets you type in calculations such as “2+2″, and then displays the result. But if you have a file which already contains the calculations, you can send it straight to bc – faster and more powerful than cutting-and-pasting the text in with your mouse.

$ cat calc.txt
2+2
$ bc < calc.txt 4 $ 

A final note: you can use two output redirect symbols together – >> – to indicate that you want to append the file, not overwrite it. Hence:

$ cat file1.txt
Contents of file1.
$ cat file2.txt
Contents of file2.txt.
$ cat file2.txt >> file1.txt
$ cat file1.txt
Contents of file1.
Contents of file2.txt.
$

(continue reading…)

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IBM RAD 7.5 on Ubuntu Karmic 32 Bit

by Samet Kilictas on Dec.08, 2009, under HowTo

IBM Rational Application Developer
Lets assume you were using ubuntu 9.04 jaunty and now you have upgraded your distribution to 9.10 karmic. Before i get into 9.10 version i had my RAD 7.5 installed and running. Then decided to upgrade my distro. I’ve read an article and futures of karmic distro, that says plenty of packages getting updated. After getting done with upgrade process i tried to run my RAD 7.5 , it was ok for the first time but there were plenty of errors on screen.

First of all when you upgrade your distro, the gcc++ package gets upgareded so libstdc++.so.5 file to libstdc++.so.6 .Unfortunately RAD 7.5 version looks for libstdc++.5.so file on your system. You have to download this file. Download it by using link below;

http://packages.debian.org/stable/base/libstdc++5

Then install this deb package (If you are running on another linux distro you have to place it just next to where your libstdc++.6.so file, you can use “locate libstdc++.so.6″ command to see where your file is). Then copy below bash script and paste it any of your text editor, save it as “run.sh”. From now on, you can use this script to run your RAD 7.5.

#!/bin/bash
export GTK_NATIVE_WINDOWS=1
/where/your/RADis &

After this process your problem should be gone. Have fun.

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How to enable TCP connections to XServer?

by Samet Kilictas on Dec.07, 2009, under Linux, Tips, Ubuntu


sudo gedit /etc/gdm/gdm.schemas

find:

<schema>
<key>security/DisallowTCP</key>
<signature>b</signature>
<default>true</default>
</schema>

shift from true to false:

<schema>
<key>security/DisallowTCP</key>
<signature>b</signature>
<default>false</default>
</schema>

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Linux desktop will wipe out Windows 7

by Samet Kilictas on Oct.15, 2009, under General

This month naked marketing muscle once again shows us how it should be done. In the World, Microsoft made it to number one as the most respected and trusted brand, ahead even of Mercedes-Benz. The people have spoken.

Quite an achievement considering Vista bombed and no amount of PR power could persuade the non-OEM consumer otherwise. Now, obviously before it was too late and the Windows brand itself was damaged, Windows 7 has been released. Word is that it is OK, better even than XP.

Thus, the hiatus that may have been the golden Window of Vista opportunity for Linux on the desktop will soon be gone. The power of the ‘brand’ coupled with a product that actually works is hard to stop. If you think that Microsoft has done a number on the Linux netbook using venerable XP and a fat cheque book then just wait for Windows 7 to get into full swing.

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Free Shell Accounts

by Samet Kilictas on Aug.21, 2009, under General

Here is a tiny list of free shell account services. I should remember them when i need it.

  • http://www.bylur.net/free/
  • http://www.red-pill.eu/freeunix.shtml *
  • http://www.rootshell.be/
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