Official RedHat Documentation Link - Very Good

XOR operation for Parity Caluclation

Sample XOR operation that will be used for recovering data during parity regeneration

A		B		C
0	XOR	0	->	0
0	XOR	1	->	1
1	XOR	0	->	1
1	XOR	1	->	0

Get date information from commands.

Get the Date output.
===============
$ date +%d -- Date
26
$ date +%D -- Date format
10/26/10
$ date +%m -- Month
10
$ date +%b -- Month
Oct
$ date +%M -- Minutes
45
$ date +%W -- Week of the year
43
$ date +%w -- Week of the day
2
$ date +%Y -- Year
2010
$ date +%y -- Year (last 2 digits)
10
$ date +%n -- New line
$ date +%l -- hour (0..12)
4
$ date +%k -- hour (0..23)
16
$ date +%N -- nano seconds
855022663
$ date +%T -- time format
16:48:14
-----------------------------------
$ set `date`
$ echo $1
Tue
$ echo $2
Oct
$ echo $3
26
$ echo $4
16:52:45
$ echo $5
IST
$ echo $6
2010
$ echo $# -- Total number of command variables.
6
-----------------------------------------------
date |cut -d" " -f1 # Replace f1 to f2,3,4,5,6 to get the values.
Tue
-------------------------
You can run a loop to check the day and run some commands according using case loop.

case `date |cut -d" " -f1` in
Mon) commands ;;
Tue) commands ;;
Wed) commands ;;
...
esac

Check top CPU or Memory utilisation process.

Find Processes that uses maximum processor utilisation
#ps -eo pid,ppid,pcpu,rss,cmd --sort pcpu

Find Processes that uses maximum Memory utilisation
#ps -eo pid,ppid,pcpu,rss,cmd --sort rss

Kill multiple jobs OR Kill all jobs of a particular user

# Create a list of specific jobs of a user
ps -ef |grep [username]|grep [jobname eg. telnet]|awk '{print $2}' > /tmp/fileout
while read userpid; do kill -9 $userpid;done < /tmp/fileout

Modify FreeNas configuration file

Editing of FreeNAS configure file is not possible from the FreeNAS shell.
To modify the configuration - Eg., /etc/fstab on FreeNAS

share /etc directory using NFS / CIFS share - ( Make sure its not a read only share)
mount /etc share on linux partition.
Use vi tool to modify the configuration file and save the configuration.

:) done.

perl module checks & installation

[root@mail ~]# instmodsh

Available commands are:

l - List all installed modules

m - Select a module

q - Quit the program

perldoc perlmodlib - Will display all modules that are installed along with the standard perl packages
perldoc perllocal - Will display all additional modules that were installed.

-----------------------

To install perl modules - (Make sure your system is connected to internet)

perl -MCPAN -e shell

cpan> o conf - will display the configurations

cpan> o conf init - Will reinitiate the configuration.

cpan> install Bundle::cpan --- Sample command to install modules.

Change Solaris Server hostname

Change the hostname in the following files:

/etc/nodename
/etc/hostname.*interface
/etc/inet/hosts
/etc/inet/ipnodes

Reverse proxy configuration on Apache

Apache Server side configuration.

mod_proxy_html installation reference link http://ubuntuforums.org/showthread.php?t=350836

wget http://apache.webthing.com/mod_proxy_html/mod_proxy_html.tgz

tar -xvzf mod_proxy_html.tgz

cd mod_proxy_html

-----------------------

apt-get install apache2-prefork-dev

apt-get install libxml2-dev

ln -s /usr/include/libxml2/libxml /usr/include/libxml

apxs2 -i -c mod_proxy_html.c

------------------------------------------

Modules for proxy settings

--------------------------------

LoadModule proxy_module modules/mod_proxy.so

LoadModule proxy_balancer_module modules/mod_proxy_balancer.so

LoadModule proxy_ftp_module modules/mod_proxy_ftp.so

LoadModule proxy_http_module modules/mod_proxy_http.so

LoadModule proxy_connect_module modules/mod_proxy_connect.so

LoadFile /usr/lib/libxml2.so.2

-----------------------------------------------------------------------------

NameVirtualHost *:443

NameVirtualHost *:80

ServerName linuxmediaserver.mlmail.net

DocumentRoot /var/www/

ErrorLog /var/log/httpd/error.log

CustomLog /var/log/httpd/access.log combined

ProxyRequests Off

Order deny,allow

Allow from all

ProxyPass / http://server.domain.com/

ProxyPassReverse / http://server.domain.com/

ServerName linuxmediaserver.mlmail.net

DocumentRoot /var/www/

ErrorLog /var/log/httpd/error.log

CustomLog /var/log/httpd/access.log combined

SSLEngine on

SSLCertificateFile /etc/httpd/ssl/mycert.pem #---------------> Generated certificate

ProxyRequests Off

Order deny,allow

Allow from all

ProxyPass / http://server.domain.com/

ProxyPassReverse / http://server.domain.com/

Apache Bench test

Apache bench test can be done to find the apache server performance.
We can run multiple simultaneous connections to the apache server and check the server response time.

Download apace bench marker from the below site.
http://www.filewatcher.com/m/ApacheBench-0.62.tar.gz.61627.0.0.html

Install Apache Bench mark -
wget ftp://ftp.eenet.ee/pub/cpan/authors/id/A/AD/ADIRAJ/ApacheBench-0.62.tar.gz
mv ApacheBench-0.62.tar.gz to /opt

tar -zxvf ApacheBench-0.62.tar.gz
cd /opt/ApacheBench-0.62
perl Makefile.PL
make
make test (requires Term::ReadKey for execute() test)
make install

Now AB is installed you can run the testing from command.
ab -n 10000 -c 5 http://(servername)/index.html

-n requests Number of requests to perform
-c concurrency Number of multiple requests to make

Result
=====
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/

Benchmarking xxx.xxx.xxx.xxx (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
Completed 4000 requests
Completed 5000 requests
Completed 6000 requests
Completed 7000 requests
Completed 8000 requests
Completed 9000 requests
Finished 10000 requests


Server Software: Apache/2.2.10
Server Hostname:
Server Port: 80

Document Path: /index.html
Document Length: 197 bytes

Concurrency Level: 10
Time taken for tests: 6.98762 seconds
Complete requests: 10000
Failed requests: 0
Write errors: 0
Total transferred: 4440000 bytes
HTML transferred: 1970000 bytes
Requests per second: 1639.68 [#/sec] (mean)
Time per request: 6.099 [ms] (mean)
Time per request: 0.610 [ms] (mean, across all concurrent requests)
Transfer rate: 710.80 [Kbytes/sec] received

=========

Powering ON or OFF system using wake on LAN

http://www.tjansson.dk/?p=83
http://www.raymond.cc/blog/archives/2007/10/21/how-to-remotely-turn-on-computer-from-lan-and-wan/

Backup and Restore root filesystem using TAR command

how to get LDAP query output of more than 1000 objects

You can always change the LDAP query output from 1000 to the number of your choice on AD using ntdsutil.exe feature. - Caution - this is not the recommended option as this will increase the maxpagefilesize on your server which can be a server performance overload.
===============================

C:\WINDOWS\system32\ntdsutil.exe: ldap policies
ldap policy: connections
server connections: connect to server lab15cust5
Binding to lab15cust5 ...
Connected to lab15cust5 using credentials of locally logged on user.
server connections: q
ldap policy: show values
MaxPageSize 2000
ldap policy: set maxpagesize to 3000
ldap policy: show values
Policy Current(New)
MaxPageSize 2000(3000)
ldap policy: commit changes
ldap policy: show values
Policy Current(New)
MaxPageSize 3000
ldap policy: q

=====================================
Other way of getting more than 1000 results without modifying the maxpagefilesize is by using -E option along with Paged Results option.
ldapsearch -E pr=100/noprompt -H ldap://xxx.xxx.xxx.xxx -x -b "dc=doman,dc=com" -D "domain\username" -W
This will show all the ldap search results even if there is max of 1000 search output results.

process status - Linux

ps auxf -- Will give the processes and child processes information in hierarchical order (grpahically)
ps -p [id]-- Process info based on JobID
ps auU [username] -- All process run by a specific user

Converstion of second timestamp to date timestamp

Some of the login information is saved on the second time stamp. This will need to be converted into a format that your system can understand.

[root@mail ~]# date;date +%s
Fri Mar 19 10:40:32 IST 2010
1268975432

To convert the second back to IST format

[root@mail ~]# date -d '1970-01-01 1268975432 sec GMT'
Fri Mar 19 10:40:32 IST 2010

[root@mail ~]# date -d@1268975432
Fri Mar 19 10:40:32 IST 2010

=================================

Setting up of SVN and WebSVN.

Procedure to create a SVN
---------------------------

Package requirement:
================

• subversion.i386 1.6.5-1 installed
• subversion-devel.i386 1.6.5-1 installed
• subversion-perl.i386 1.6.5-1 installed
• subversion-python.i386 1.6.5-1 installed

Creation of SVN Directory and initialization of SVN
SVN directory location is /srv/svn/repos

• mkdir /srv/svn/repos
• svnadmin create --fs-type fsfs /srv/svn/repos

Import the initial code into SVN

• svn import -m "Initial import" project1 file:///home/project1code

Configure SVN to view changes using WebSVN.

Download a copy of WebSVN on the server

• http://websvn.tigris.org/servlets/ProjectDocumentList;jsessionid=24F17B3F5279F7DE3BB39F064A2C4A03

Copy the the extracted websvn to /var/www/html/webSVN

• cp /var/www/html/webSVN/include/distconfig.php to /var/www/html/webSVN/include/config.php

• modify /var/www/html/webSVN/include/config.php

$config->setDiffPath('/usr/bin/');
$config->setSedPath('/bin/');
$config->setTarPath('/bin/');
$config->setGZipPath('/bin/');
$config->setZipPath('/usr/bin/');
$config->parentPath('/srv/svn/repos'); -------- > Path of your repository
$config->addTemplatePath($locwebsvnreal.'/templates/calm/');
$config->addTemplatePath($locwebsvnreal.'/templates/BlueGrey/');
$config->addTemplatePath($locwebsvnreal.'/templates/Elegant/');
$config->setTemplatePath($locwebsvnreal.'/templates/BlueGrey/');

Now from your web-browser access http://servername/webSVN - this should give you access to your svn thru web interface