Unix-Like for Life

python.init()

2009-09-01T05:31:00.001-07:00

Here is the small python recipient to start python development in any recent GNU/Linux environment right away:

0-) python is already installed,
1-) install ipython, very smart, python interpreter,
2-) All you need is Kate, but if you will go really deep it is worth to install eclipse and its pyDev plugin.

for help and little snippet checking ipython is more than enough, kate is a good and wise editor for development.Don't forget to tell kate fill the gaps with spaces instead of tabulators, that must be global policy for all kinds of development except for writing Makefiles.

Enabling core dump feature

2009-08-28T09:19:00.000-07:00

Use

ulimit -c unlimited

to enable application core dump

using gdb and gdbserver

2009-08-17T06:54:00.000-07:00

Imagine you need to use an embedded system debugger.One of the options is using gdb and gdbserver all together

To do this first you need to setup your toolchain at x86 machine.In that example out embedded system will be in ST.

Install gdbserver your embedded directory.In order to work with gdbserver we can use tcp connection to out x86 machine like that:

/root/gdbserver 192.168.1.136:1234 bin/${ST binary to debug} ${arguments to pass binary}

It's handy to get this command work in a very bottom of a shell script file after all done, environment variables, etc..

with this command we will start debugging session and awaits connection from relevant machine(x86 machine in that case)

Meantime we need to open our tcp connection to gdbserver like:

root@home$ gdb ${EXECUTABLE_FILE}
(gdb)target remote ${ip address of embedded machine}:${tcp port number of embedded machine}

after connection established, we need to enter gdb command c
(gdb) c

c stands for continue, since debugging already started that is the command we should send to gdbserver with our local gdb client.
But before starting gdb client do not forget to set corrent binary executable as well.Otherwise you will not be able to set breakpoints, and other useful stuff inside gdb.

so remote debugging starts

login to ssh without a password

2009-08-15T15:55:00.001-07:00

Your aim

You want to use Linux and OpenSSH to automize your tasks. Therefore you need an automatic login from host A / user a to Host B / user b. You don't want to enter any passwords, because you want to call ssh from a within a shell script.
How to do it

First log in on A as user a and generate a pair of authentication keys. Do not enter a passphrase:

a@A:~> ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/a/.ssh/id_rsa):
Created directory '/home/a/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/a/.ssh/id_rsa.
Your public key has been saved in /home/a/.ssh/id_rsa.pub.
The key fingerprint is:
3e:4f:05:79:3a:9f:96:7c:3b:ad:e9:58:37:bc:37:e4 a@A

Now use ssh to create a directory ~/.ssh as user b on B. (The directory may already exist, which is fine):

a@A:~> ssh b@B mkdir -p .ssh
b@B's password:

Finally append a's new public key to b@B:.ssh/authorized_keys and enter b's password one last time:

a@A:~> cat .ssh/id_rsa.pub | ssh b@B 'cat >> .ssh/authorized_keys'
b@B's password:

From now on you can log into B as b from A as a without password:

a@A:~> ssh b@B hostname
B

A note from one of our readers: Depending on your version of SSH you might also have to do the following changes:

* Put the public key in .ssh/authorized_keys2
* Change the permissions of .ssh to 700
* Change the permissions of .ssh/authorized_keys2 to 640

Linux process state codes

2009-07-31T00:01:00.001-07:00

Here are the different values that the s, stat and state output specifiers
(header "STAT" or "S") will display to describe the state of a process.
D Uninterruptible sleep (usually IO)
R Running or runnable (on run queue)
S Interruptible sleep (waiting for an event to complete)
T Stopped, either by a job control signal or because it is being traced.
W paging (not valid since the 2.6.xx kernel)
X dead (should never be seen)
Z Defunct ("zombie") process, terminated but not reaped by its parent.

For BSD formats and when the stat keyword is used, additional characters may
be displayed:
< high-priority (not nice to other users)
N low-priority (nice to other users)
L has pages locked into memory (for real-time and custom IO)
s is a session leader
l is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+ is in the foreground process group

The "find"

2009-02-12T09:57:00.000-08:00

Many *nix users are familiar with the find tool, but not all of them knows its -exec parameter.

Assume you need to find specific function or set of string-lets say printf-among lots of c source
files, what you need to do is like:

$ find . -name "*" -exec grep -i printf {} \; -print

this process will look inside of every single file on current directory-yes binary ones included!-and list files that contains printf at least one time in very nice form.This kind of commands really help.

Load balancing by using Vmware and Linux

2008-08-20T23:29:00.000-07:00

Here I will describe load balancing guide using linux with vmware workstation 6

First step is install 1 linux os(I chosed sles 10) and clone 2 more virtual machines of that machine .We will be using 1 virtual gateway and 2 virtual network members.

Then create 2 virtual switches named vmnet8 and bridged.
connect one of the gateway interface thru bridged switch-say eth1- and other to vmnet8.
Give ip address to eth1 as you connect to internet -dhcpd e.g.- and give static ip and netmask to eth0-10.0.0.2/24 e.g.Here eth0 will be our private 10.0.0.0 network's gateway and eth1 will be our wan door.When we generate http 80-or 8080- requests it should route us to the one of the internal zone member's 80.

After installation configure gateway with:

# echo net.ipv4.ip_forward = 1 >> sysctl.conf

and reload sysctl config with :

# sysctl -p
and double-check /proc/sys/net/ipv4/ip_forward it should be 1

Second step is configure our iptables nat rules.Remember we don't have to run iptables as a service if we only want iptables running our nat rules.

Here our basic nat rules:

# iptables -t nat -F // for flushing exising iptables nat rules
# iptables -t nat -I POSTROUTING -j MASQUERADE // create an postrouting masquerade
# iptables -t nat -I PREROUTING -d 136.10.195.84 -p tcp --dport 8080 -j DNAT --to 10.0.0.3:80
// finally route all packages which come from 136.10.195.84 iface(eth1) to 10.0.0.3:80 (our member 1 apache server) via our eth0 iface on the gateway

Test step; run apache server at 10.0.0.3(@ member 1) and try to load 136.10.195.84:8080 see if it's works

add a nice user

2008-02-20T15:29:00.000-08:00

Add a nice unprivileged user to specific group..

First add a group called lfs

# groupadd lfs
then add a user with valid shell,home,member of group lfs called lfs
# useradd -s /bin/bash -g lfs -m -k /dev/null lfs
-m creates home directory..
-k give alternate /skel dir..if you specify it to /dev/null that means you won't use any preconfig value of user lfs
-g add user to group lfs

that's all..

Unix kullaniminda hizi arttiran tavsiyeler

2008-01-03T16:02:00.000-08:00

Unix kullaniminda konso ortaminda daha hizli ve tekili olmak amaciyla IBM su tavsiyeleri yapiyor(ozetin ozeti):

1-) Ornegin /tmp icerisinde /a/b/c dizinlerinin yaratilmasina ihtiyac duyuroruz.Bunu cd ve mkdir komutlariyla her defasinda bir dizin iceriye girip yeni bir dizin olusturmak yerine:

$mkdir -p tmp/a/b/c
komutuyla kisaca halledebiliriz.Ayrica bu yontemin scriplerdede oldukca etkili oldugundan bahsedilmis;

2-)Herhangibi dizindeki bir .tar arsivini baska bir dizine acmaya ihtiyacimiz var.Bunun icin oncelikle .tar dosyasini o dizine tasiyip, daha sonra .tar arsivini acmamiza gerek yok;

$tar xvf linux.tar -C /tmp/a/b/c

gibi bir komut bize hiz kazandirir.

3-)Bazi kontrol komutlariyla ( || && gibi) komutlar daha komplex ve daha etkili hale gelebilirler;

$ cd /tmp/a/b/c && tar xvf ~/archive.tar

Bu durumda aradaki && operatoru nedeniyle birinci komutun basarisizlikla sonulanmasi
durumunda tar komutu calistirilmaz.Buna benzer /tmp dizini altinda a/b/c dizinlerinin var olup olmadigini ogrenen, yoksa olusturan komut su sekilde olabilir;

$ cd /tmp/a/b/c || mkdir -p /tmp/a/b/c
Bu durumda ilk komut (0) dondurmezse, yani basarisiz olursa mkdir komutu calisir, aksi hakde tam tersi olur..

4-) Gercekten uzun bir komut yazmak durumundasiniz ve o anki kullandiginiz terminalle ilgili maymunluklar yapmak
istemiyorsaniz ifadenizi "\" operatoru ile satirlara bolebilir ve daha az acisin bir komutu gerceklemis olursunuz

$ cd /tmp/a/b/c || \
> mkdir -p /tmp/a/b/c && \
> tar xvf -C /tmp/a/b/c ~/archive.tar
5-) xargs kullanin.Ornegin bir dizindeki tum elemanlarin file komutunun ciktilarina ihtiyaciniz var;

$ls -laF | xargs file

simdilik bu kadar efendim

FreeBSD soundcard config

2007-08-31T03:42:00.000-07:00

Uzun zamandir fellik fellik aradigim snd_hda modulunu ve gerekli config belgisini buldum..

Ariff isimli bir kardesimiz, canimiz, cigerimiz linuxteki snd_hda intel ALC880 modulunu FreeBSD portolayini gerceklestirmis.Bunlar icin su linkteki aciklamalari takip edip;bu linkteki dosyalardan faydalanabilirsiniz..

FreeBSD mysql config

2007-08-31T03:31:00.000-07:00

FreeBSD de mysql conf biraz daha farkli.FreeBSD guvenlik uygulamalari dogrultusunda portlarindan kurdugunuz mysqlclient mysql kullanicisindan baskasiyla acmaniza izin vermiyor.Aslina bakarsaniz dogru olanda bu.Bu durumda linuxten farkli olarak birkac ek ayarlama yapmak gerekiyor.Portlardan mysql kurulumundan sonra linuxte oldugu gibi;

# mysql_install_db

komutunu girerek default mysql db dosyalari olusturuyoruz.Daha sonra FreeBSD de default mysql dizini olan /var/db/mysql dizinini mysql kullanicisi erisebilecek sekilde;

# chown -R mysql /var/db/mysql/

ve

# chgrp -R mysql /var/db/mysql/

komutlarini girdikten sonra geriye sadece mysqld calistirmak kaliyor;

# /usr/local/bin/mysqld_safe -user=mysql &

boylece mysql hazir.Her sistem acilisinda mysqli baslatmak icin

# echo 'mysql_enable="YES"' >> /etc/rc.conf

komutundan yaralanilir.Istege bagli olarak mysql root passwordu ayni linuxte oldugu gibi degistirilir..

Mysql config

2007-08-25T12:44:00.000-07:00

After installing mysql on your linux box there is some configuration that you should make;

1-> Assign a password for "root" account.Give mysql that commands:

mysql> UPDATE user
-> SET password=password("newpassword")
-> WHERE user="root";

The new root passwd is now "newpassword"

2-> Create a new database and assign all options on specific user:
imagine that you need to create a new database for your holy music player amarok, and you wanna use mysql as database..

mysql> create database amarok;
mysql> create user amarokuser;
mysql> GRANT ALL PRIVILEGES ON amarok.* TO 'amarokuser'@'localhost'
>IDENTIFIED BY 'some_pass' WITH GRANT OPTION;
mysql> flush privileges;

That's all.You can use amarok database with amarokuser in amarok application.. cool ha?

wireless networking basics

2007-06-30T05:11:00.000-07:00

A little info about wireless networking;

ESSID : The Extended Service Set Identification (ESSID) simpliest way is the name of the Access Point.You see ESSID as the string when you search for the AP

BSSID : MAC address of AP.Its an id of AP.

Wireless Channels : Wireless AP and clients talks to each other by using 2.4-2.5 ghz radio signals by default.Its a standard at IEEE 802.11b/g.

Wireless Security Models : To provide security between access nodes, IEEE defined 2 ways of method : WEP and WPA.WPA is stronger than WEP and support 128 bit authentication keys.WEP is also easy to recover password by using programs such as aircack or airsnort etc..

This things generally happens when a wireless client(notebook etc) attemps to connect to a Open Security based(no key authentication) AP :
1-> Client sends a request to AP.
2-> The access point authenticates the client.
3-> Client connects to AP.

But if AP protected by a WEP connection turns this :

The following steps occur when two devices use Shared Key(WEP) Authentication:

1. The client sends an authentication request to the access point.

2. The access point sends challenge text to the station.

3. The station uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and it sends the encrypted text to the access point.

4. The access point decrypts the encrypted text using its configured WEP key that corresponds to the station's default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the station share the same WEP key, and the access point authenticates the station.Because of that it calls Shared Key.

5. The client connects to the network.

There is two way of key generation model at WEP : 64 bits or 128 bits.24 of 64 bits is using for a 40 bit key generation.That means only 5 character key (40bits) can be generated by 64 bit authentication...

WPA Based wifi Security

WPA security model highly increases wireless security against WEP.Unlikely WEP, TKIP method required at WPA security model.TKIP is the new encrypt algorithm stronger than WEP.At one day you can sniff and crack WEP key.But WPA requires to collect more than one million package and "handshakes" between client and AP.

that link may work :p

Slackware xorg.conf

2007-05-12T06:11:00.000-07:00

Slackware de xorgu en kolay configure etmenin bir diger yoluda, donaniminizi iyi taniyan bir dagitim bulup(Pardus,Knoppix vb) bu dagitimlarin olusturdugu xorg.conf dosyasini direkt olarak slackware e tasimaktir.Daha sonra xorgun talep ettigi modulleri iceren bir kernel derlenerek
daha once kullandiginiz dagitim seviyesinde xorgu kullanabilirsiniz.Bu yontem baya bi kopya icermekte olup yok ben bunlarla ugrasmayi seviyorum diyenlere tavsiye edilmez :P..

Kaybolan root passwordlari ve cozumu..

2007-02-26T07:56:00.000-08:00

Unix-like diye nitelendirdigimiz isletim sistemlerini kullananlar bilirler, eger root passwordunuzu yitirmisseniz , yada sizinde benim gibi canı sıkıldıgında root passwordunuzu degistiren saklaban* arkadaslariniz varsa(Fethi ve Orhana opucukler :D) artik o sistem uzerinde pekte bir gucunuz kalmaz hatta hicbirsey yapamazsiniz.Bu durumdan kurtulmak icin kullanabileceginiz cesitli yontemler var;
Herseyden once belirtmeliyimki Unix ve turevlerinde passwordlardan sorumlu dosya :/etc/shadow dosyasidir.Bu dosyayi actiginizda soyle birseyle karsilasirsiniz :

root:$1$JvYQL23Up$k2aJ6wD47tAT1nIYRNkAO1:13570:0:::::
bin:*:9797:0:::::
daemon:*:9797:0:::::
adm:*:9797:0:::::
sync:*:9797:0:::::
shutdown:*:9797:0:::::
halt:*:9797:0:::::
mail:*:9797:0:::::
news:*:9797:0:::::
operator:*:9797:0:::::
man:*:9797:0:::::
postmaster:*:9797:0:::::
dialout:*:13094:0:99999:7:::
ftp:*:9797:0:::::
named:*:13094:0:99999:7:::
mysql:*:13094:0:99999:7:::
postgres:*:13094:0:99999:7:::
apache:*:13094:0:99999:7:::
dovecot:*:13094:0:99999:7:::
dbus:*:13094:0:99999:7:::
hal:*:13094:0:99999:7:::
polkit:*:13094:0:99999:7:::
postfix:*:13094:0:99999:7:::
smmsp:*:13094:0:99999:7:::
firebird:*:13094:0:99999:7:::
dhcp:*:13094:0:99999:7:::
ldap:*:13094:0:99999:7:::
clamav:*:13094:0:99999:7:::
ntlmaps:*:13094:0:99999:7:::
ntp:*:13094:0:99999:7:::
tss:*:13094:0:99999:7:::
pnp:*:13094:0:99999:7:::
slack:$1$31141276$uaXFYNdmdEn12qN2OA3aD1:13094:0:99999:7:::
nobody:*:9797:0:::::

Bu dosyada suanda slack ve tabiki root kullanicilari var.
Ornegin root kullanicisinin passwd sinin sifrelenmis halidir :

root:$1$JvYQL23Up$k2aJ6wD47tAT1nIYRNkAO1:13570:0:::::

burada ki dizini su sekle donusturebiliriz :
root::0:0:root:/:/bin/sh

bu sekilde root passwd unu sifirladik..bundan sonra passwd a gerek kalmadan sisteme girebiliriz

Bir diger secenek ise eger elinizde baska sahdow dosyalari varsa (ornegin sistemde baska linux-unix sistemler varsa yada knoppix benzeri baska bir livecd ile) root passwd u olusturarak elde edilen shadow
dosyasini ozgun shadow dosyasi ile degistirebilirsiniz.Boylece diger sistemde gecerli olan passwd ler
artik yeni sistemdede gecerlidir.Herkese saglam passwdlar kazasiz belasiz gunler efendim..

Intel 915GM ye ozel ekran karti ayarlamasi

2007-02-22T15:35:00.000-08:00

Eger sizinde 915 Intel chipsetli bir laptopunuz var, 15.4" inch bir monitorunuz var ve ekran cozunurlugunu 1280x800 'e ayarlayamiyorsaniz 915resolution adli program tam size gore..programin kullanimi basit..
program temel olarak sistemin tanimadigi ekran kartinin biosunu sisteme tanitmaya yariyor..boylece monitorun olmasi gereken cozunurluge geciriyor..kullanimi su sekilde efendim:

>Temel olarak program X acilmadan once baslamali o yuzden programin acilis scriptini
(dagitima gore degisiyor ,rc.local-local.start gibi isimleri olabilir) Slackware 'de varsayilan acilis scripti olan cd /etc/rc.d/rc.local ( pardus te ise /etc/conf.d/local.start )scripti su sekilde duzenlenmelidir:

#!/bin/sh
#
# /etc/rc.d/rc.local: Local system initialization script.
#
# Put any local startup commands in here. Also, if you have
# anything that needs to be run at shutdown time you can
# make an /etc/rc.d/rc.local_shutdown script and put those
# commands in there.

if [ -x /bin/915resolution ]; then
exec /bin/915resolution -l 58 1280 800 32
fi

Efendim tum bu ayarlari yaptiktan sonra Slackware imiz 1280x800 ekranmodunda ve 32 bit destekli olaak acilmasi lazim..yok eger genede olmadi derseniz scripti tekrar gozden gecirin..genede olmadi derseniz masaustunde saga tiklatip Configure Desktop seceneginden ekran cozunurlugu kismini kurcalayin-cozunurlugu degistirip tekrar eski haline getirin ,bana bir keresinde olmustu..-tum bu kontrollerden sonra olmasi lazim..yok olmadi derseniz su python scripti isinizi gormesi lazim(Pardus icin):

#!/usr/bin/python
#-*-coding:utf8 -*-

# face the reality

import re
import os

def get915():
print ">installing.."
os.system("pisi -y it 915resolution")
print ">installed now configuring.."

def change():
conf = open("/etc/conf.d/local.start","a") # open file ro
print "file opened.."

conf.writelines("\nif [ -x /usr/bin/915resolution ]; then\n" \
"\texec /usr/bin/915resolution 58 1280 800 32\n" \
"fi\n");

def changeMod():
os.system("chmod +x /etc/conf.d/local.start")

get915()
change()
changeMod()
print ">done!"

ooldu o zaman