Couchbase Server

Couchbase Server is the world’s most complete, scalable, and highest performing NoSQL distributed database.

yum install -y pkgconfig

yum install openssl098e

wget http://packages.couchbase.com/releases/3.0.1/couchbase-server-enterprise-3.0.1-centos6.x86_64.rpm

rpm -ivh couchbase-server-enterprise-3.0.1-centos6.x86_64.rpm
Preparing...                ########################################### [100%]
Warning: Transparent hugepages may be used. To disable the usage
of transparent hugepages, set the kernel settings at runtime with
echo never > /sys/kernel/mm/transparent_hugepage/enabled
Warning: Transparent hugepages may be used. To disable the usage
of transparent hugepages, set the kernel settings at runtime with
echo never > /sys/kernel/mm/redhat_transparent_hugepage/enabled
Warning: Swappiness is not 0.
You can set the swappiness at runtime with
sysctl vm.swappiness=0
Minimum RAM required  : 4 GB
System RAM configured : 3.74 GB

Minimum number of processors required : 4 cores
Number of processors on the system    : 2 cores

   1:couchbase-server       ########################################### [100%]
Starting couchbase-server[  OK  ]

You have successfully installed Couchbase Server.
Please browse to http://mb1udarmiweb02.pearsontc.com:8091/ to configure your server.
Please refer to http://couchbase.com for additional resources.

Please note that you have to update your firewall configuration to
allow connections to the following ports: 11211, 11210, 11209, 4369,
8091, 8092, 18091, 18092, 11214, 11215 and from 21100 to 21299.

By using this software you agree to the End User License Agreement.
See /opt/couchbase/LICENSE.txt.

/etc/init.d/couchbase-server status
couchbase-server is running

Ref:
http://www.couchbase.com/nosql-databases/about-couchbase-server#ElasticScalability
http://docs.couchbase.com/couchbase-manual-2.5/cb-install/

Update time zone in Linux

date
Thu Nov 27 19:40:33 EST 2014

ls -l /etc/localtime
lrwxrwxrwx 1 root root 39 Nov 27 19:40 /etc/localtime -> /usr/share/zoneinfo/Australia/Melbourne

unlink /etc/localtime

ln -s /usr/share/zoneinfo/Asia/Kolkata /etc/localtime

ls -l /etc/localtime
lrwxrwxrwx 1 root root 32 Nov 27 14:08 /etc/localtime -> /usr/share/zoneinfo/Asia/Kolkata

date
Thu Nov 27 14:09:15 IST 2014

Ref:- http://www.linuxnix.com/2014/11/linuxunix-how-update-timezone-in-a-system.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+TheLinuxJuggernaut+%28The+Linux+Juggernaut%29

PHP Warning: PHP Startup: Unable to load dynamic library

Scenario :-

php -v

PHP Warning:  PHP Startup: Unable to load dynamic library '/usr/lib64/php/modules/module.so' - /usr/lib64/php/modules/module.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP 5.3.3 (cli) (built: Sep 10 2014 05:27:26)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies

cat /etc/php.d/mcrypt.ini
; Enable mcrypt extension module
extension=module.so

but module.so not exist in /usr/lib64/php/modules/

Resolution :-
uninstall the php-mcrypt and reinstall the suitable rpm

rpm -e php-mcrypt-5.3.3-1.el6.rf.x86_64
wget ftp://ftp.pbone.net/mirror/download.fedora.redhat.com/pub/fedora/epel/6/x86_64/php-mcrypt-5.3.3-3.el6.x86_64.rpm
rpm -ivh php-mcrypt-5.3.3-3.el6.x86_64.rpm

php -v
PHP 5.3.3 (cli) (built: Sep 10 2014 05:27:26)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies

cat /etc/php.d/mcrypt.ini
; Enable mcrypt extension module
extension=mcrypt.so

now mcrypt.so exist in /usr/lib64/php/modules/mcrypt.so

Monitor MySQL performance with innotop

Innotop is an excellent command line program, similar to ‘top command‘ to monitor local and remote MySQL servers running under InnoDB engine.

yum install innotop

innotop -u root -p 'mysqlpassword'

Innotop Help
Press “?” to get the summary of command line options and usage.

Switch to a different mode:
   A  Dashboard         I  InnoDB I/O Info     Q  Query List
   B  InnoDB Buffers    K  InnoDB Lock Waits   R  InnoDB Row Ops
   C  Command Summary   L  Locks               S  Variables & Status
   D  InnoDB Deadlocks  M  Replication Status  T  InnoDB Txns
   F  InnoDB FK Err     O  Open Tables         U  User Statistics

Actions:
   d  Change refresh interval        p  Pause innotop
   k  Kill a query's connection      q  Quit innotop
   n  Switch to the next connection  x  Kill a query

Other:
 TAB  Switch to the next server group   /  Quickly filter what you see
   !  Show license and warranty         =  Toggle aggregation
   #  Select/create server groups       @  Select/create server connections
   $  Edit configuration settings       \  Clear quick-filters
Press any key to continue

Non-Interactively

innotop -u root -p 'mysqlpassword' --count 5 -d 1 -n

Monitor Remote Database

innotop -u username -p password -h hostname

Ref : -
http://www.tecmint.com/install-innotop-to-monitor-mysql-server-performance/
http://linux.die.net/man/1/innotop

SeaLion Monitoring in Linux

Install and configure SeaLion

wget https://s3.amazonaws.com/sealion.com/3.2.3/sealion-agent-3.2.3-noarch.tar.gz
tar -xzvf sealion-agent-3.2.3-noarch.tar.gz
cd sealion-agent

sudo ./install.sh -o 299ade98-ab92-44bd-a9e6-3cefd1a9aeda

dependency : SeaLion agent requires python version 2.6 or above

Ref : -
https://www.youtube.com/watch?v=fLqVQd1SMmY
https://sealion.com

Bash Code Injection Vulnerability

rpm -qa | grep bash

bash-3.2-32.el5

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
vulnerable
this is a test
You have new mail in /var/spool/mail/root

yum upgrade bash

env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
bash: warning: x: ignoring function definition attempt
bash: error importing function definition for `x'

rpm -qa | grep bash
bash-3.2-33.el5.1

Ref :- https://access.redhat.com/articles/1200223

Install mod_ssl on Apache2 - Ubuntu

Steps to install mod_ssl on Apache2 - Ubuntu

apt-get install mod_ssl

dpkg -S mod_ssl.so
apache2.2-bin: /usr/lib/apache2/modules/mod_ssl.so

a2enmod ssl
Module ssl already enabled

To make sure that the SSL module was loaded properly :

apache2ctl -t -D DUMP_MODULES | grep ssl
[Thu Sep 25 11:28:16 2014] [warn] NameVirtualHost *:80 has no VirtualHosts
Syntax OK
ssl_module (shared)

Mutual SSL authentication in Ubuntu

Two-way SSL using CA certificates

 cd /root

 mkdir CA

 cd CA

 mkdir newcerts private

vi openssl.cnf

#
# OpenSSL configuration file.
#
# Establish working directory.
dir = .
ts = 1024 # Size of keys
default_keyfile = key.pem # name of generated keys
default_md = md5 # message digest algorithm
string_mask = nombstr # permitted characters
distinguished_name = req_distinguished_name
req_extensions = v3_req

[ ca ]

default_ca = CA_default

[ CA_default ]

serial = $dir/serial
database = $dir/index.txt
new_certs_dir = $dir/newcerts
certificate = $dir/cacert.pem
private_key = $dir/private/cakey.pem
default_days = 365
default_md = md5
preserve = no
email_in_dn = no
nameopt = default_ca
certopt = default_ca
policy = policy_match

[ policy_match ]

countryName = match
stateOrProvinceName = match
organizationName = match
organizationalUnitName = optional
commonName = supplied
emailAddress = optional

[ req ]

default_md = sha1
distinguished_name = req_distinguished_name

[ req_distinguished_name ]

countryName = Country
countryName_default = IN
countryName_min = 2
countryName_max = 2
localityName = Locality
stateOrProvinceName_default = Karnataka
localityName_default = Bangalore
organizationName = Organization
organizationName_default = edurite
commonName = Common Name
commonName_max = 64

[ certauth ]

subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer:always
basicConstraints = CA:true

[ server ]

basicConstraints = CA:FALSE
keyUsage = digitalSignature, keyEncipherment, dataEncipherment
extendedKeyUsage = serverAuth
nsCertType = server

[ client ]

basicConstraints = CA:FALSE
keyUsage = digitalSignature, keyEncipherment, dataEncipherment
extendedKeyUsage = clientAuth
nsCertType = client

[ v3_req ]

basicConstraints = CA:FALSE
subjectKeyIdentifier = hash

Generate self-signed certificate

 openssl req -config ./openssl.cnf -newkey rsa:2048 -nodes -keyform PEM -keyout ca.key -x509 -days 3650 -extensions certauth -outform PEM -out ca.cer

 openssl genrsa -out server.key 2048

 openssl req -config ./openssl.cnf -new -key server.key -out server.req

 openssl x509 -req -in server.req -CA ca.cer -CAkey ca.key -set_serial 100 -extfile openssl.cnf -extensions server -days 365 -outform PEM -out server.cer

 rm server.req

 openssl genrsa -out client.key 2048

openssl req -config ./openssl.cnf -new -key client.key -out client.req

 openssl x509 -req -in client.req -CA ca.cer -CAkey ca.key -set_serial 101 -extfile openssl.cnf -extensions client -days 365 -outform PEM -out client.cer

 openssl pkcs12 -export -inkey client.key -in client.cer -out client.p12

 rm client.key client.cer client.req

vi /etc/apache2/sites-available/default

<VirtualHost *:443>
        ServerAdmin webmaster@localhost
        ServerName 10.98.33.136:443

        DocumentRoot /var/www
        <Directory />
                Options FollowSymLinks
                AllowOverride None
        </Directory>
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all
        </Directory>

        ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
        <Directory "/usr/lib/cgi-bin">
                AllowOverride None
                Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
                Order allow,deny
                Allow from all
        </Directory>

        ErrorLog ${APACHE_LOG_DIR}/error.log

        # Possible values include: debug, info, notice, warn, error, crit,
        # alert, emerg.
        LogLevel warn

        CustomLog ${APACHE_LOG_DIR}/access.log combined

    Alias /doc/ "/usr/share/doc/"
    <Directory "/usr/share/doc/">
        Options Indexes MultiViews FollowSymLinks
        AllowOverride None
        Order deny,allow
        Deny from all
        Allow from 127.0.0.0/255.0.0.0 ::1/128
    </Directory>
SSLEngine on
LogLevel warn
SSLProtocol all -SSLv2
SSLCipherSuite HIGH:MEDIUM
SSLVerifyClient require
SSLVerifyDepth 10
SSLCertificateFile /etc/apache2/ssl/apache.crt
SSLCertificateKeyFile /etc/apache2/ssl/apache.key
#SSLCACertificateFile /etc/apache2/ssl/ca.cer
</VirtualHost>

/etc/init.d/apache2 restart

./OpenSSL_Client rname@some.com 365 passwd /var/www/html/CERT

Now Import the P12 file to the browser.

Ref :- http://www.flatmtn.com/article/setting-openssl-create-certificates

Two-way SSL authentication

Two-way SSL authentication or mutual SSL authentication or client
authentication works by resolving its identity to SSL server with a use of
the client certificate.

All certificates will be issued by using OpenSSL application and openssl.cnf
configuration file.

 cd /root

 mkdir CA

 cd CA

 mkdir newcerts private

 vi /root/CA/openssl.cnf

#
# OpenSSL configuration file.
#
# Establish working directory.
dir = .
ts = 1024 # Size of keys
default_keyfile = key.pem # name of generated keys
default_md = md5 # message digest algorithm
string_mask = nombstr # permitted characters
distinguished_name = req_distinguished_name
req_extensions = v3_req

[ ca ]

default_ca = CA_default

[ CA_default ]

serial = $dir/serial
database = $dir/index.txt
new_certs_dir = $dir/newcerts
certificate = $dir/cacert.pem
private_key = $dir/private/cakey.pem
default_days = 365
default_md = md5
preserve = no
email_in_dn = no
nameopt = default_ca
certopt = default_ca
policy = policy_match

[ policy_match ]

countryName = match
stateOrProvinceName = match
organizationName = match
organizationalUnitName = optional
commonName = supplied
emailAddress = optional

[ req ]

default_md = sha1
distinguished_name = req_distinguished_name

[ req_distinguished_name ]

countryName = Country
countryName_default = IN
countryName_min = 2
countryName_max = 2
localityName = Locality
stateOrProvinceName_default = Karnataka
localityName_default = Bangalore
organizationName = Organization
organizationName_default = edurite
commonName = Common Name
commonName_max = 64

[ certauth ]

subjectKeyIdentifier = hash
authorityKeyIdentifier = keyid:always,issuer:always
basicConstraints = CA:true

[ server ]

basicConstraints = CA:FALSE
keyUsage = digitalSignature, keyEncipherment, dataEncipherment
extendedKeyUsage = serverAuth
nsCertType = server

[ client ]

basicConstraints = CA:FALSE
keyUsage = digitalSignature, keyEncipherment, dataEncipherment
extendedKeyUsage = clientAuth
nsCertType = client

[ v3_req ]

basicConstraints = CA:FALSE
subjectKeyIdentifier = hash

 echo '01' > serial
 touch index.txt

 to generate self-signed certificate

 openssl req -config ./openssl.cnf -newkey rsa:2048 -nodes -keyform PEM -keyout ca.key -x509 -days 3650 -extensions certauth -outform PEM -out ca.cer

 openssl genrsa -out server.key 2048

 openssl req -config ./openssl.cnf -new -key server.key -out server.req

 openssl x509 -req -in server.req -CA ca.cer -CAkey ca.key -set_serial 100 -extfile openssl.cnf -extensions server -days 365 -outform PEM -out server.cer

 rm server.req

 openssl genrsa -out client.key 2048

openssl req -config ./openssl.cnf -new -key client.key -out client.req

 openssl x509 -req -in client.req -CA ca.cer -CAkey ca.key -set_serial 101 -extfile openssl.cnf -extensions client -days 365 -outform PEM -out client.cer

 openssl pkcs12 -export -inkey client.key -in client.cer -out client.p12

 rm client.key client.cer client.req

vi /etc/httpd/conf.d/ssl.conf

LoadModule ssl_module modules/mod_ssl.so
AddType application/x-x509-ca-cert .crt
AddType application/x-pkcs7-crl .crl

Listen 443

<VirtualHost 172.16.0.14:443>
DocumentRoot "/var/www/SSL/digitally"
CheckSpelling on
DirectoryIndex opsindex.php
ServerName 172.16.0.14
ServerAdmin root@localhost
ErrorLog logs/ssl_error_log
TransferLog logs/ssl_access_log
LogLevel warn
SSLEngine on
SSLProtocol all -SSLv2
SSLCipherSuite HIGH:MEDIUM
SSLCertificateFile /etc/httpd/conf/ssl/server.cer
SSLCertificateKeyFile /etc/httpd/conf/ssl/server.key
SSLVerifyClient require
SSLVerifyDepth 10
SSLCACertificateFile /etc/httpd/conf/ssl/ca.cer
<Files ~ "\.(cgi|shtml|phtml|php3?)$">
SSLOptions +StdEnvVars
</Files>
SetEnvIf User-Agent ".*MSIE.*" \
nokeepalive ssl-unclean-shutdown \
downgrade-1.0 force-response-1.0
CustomLog logs/ssl_request_log \
"%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"
</VirtualHost>

 httpd -S

 /etc/init.d/httpd/restart

 mkdir -p /var/www/html/CERTS

./OpenSSL_Client rname@some.com 365 passwd /var/www/html/CERTS

Now Import the P12 file to the browser.

Ref :- http://www.flatmtn.com/article/setting-openssl-create-certificates

Purge logs of MySQL

The PURGE BINARY LOGS statement deletes all the binary log files listed in the log index file prior to the specified log file name or date. BINARY and MASTER are synonyms. Deleted log files also are removed from the list recorded in the index file, so that the given log file becomes the first in the list.

Examples:-

mysql> SHOW BINARY LOGS;
+------------------+-----------+
| Log_name         | File_size |
+------------------+-----------+
| mysql-bin.000034 |  14785707 |
| mysql-bin.000035 |       143 |
| mysql-bin.000036 |       143 |
| mysql-bin.000037 |       120 |
+------------------+-----------+
4 rows in set (0.00 sec)

mysql> PURGE BINARY LOGS BEFORE '2014-09-10';

mysql> PURGE BINARY LOGS BEFORE '2013-04-22 09:55:22';

mysql>PURGE BINARY LOGS TO 'mysql-bin.000015';


ref : https://mariadb.com/kb/en/mariadb/documentation/sql-commands/administration-commands/sql-commands-purge-logs/

rsync without prompt for password

Do rsync without prompt for password, useful for cronjob and scripting.

sshpass -p "password" Source-path Destination-path

example:-
sshpass -p "mypassword" rsync -avzpW --recursive root@10.11.11.10:/data/testdata /data/

SSL Certificate on Ubuntu Server

Install SSL Certificate on Ubuntu Server

sudo apt-get install apache2
ifconfig
brose 10.98.33.136
It works!

a2enmod ssl

service apache2 restart

mkdir /etc/apache2/ssl

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/apache2/ssl/apache.key -out /etc/apache2/ssl/apache.crt

Country Name (2 letter code) [AU]:IN
State or Province Name (full name) [Some-State]:KA
Locality Name (eg, city) []:Bangalore
Organization Name (eg, company) [Internet Widgits Pty Ltd]:Pearson
Organizational Unit Name (eg, section) []:Pearson
Common Name (e.g. server FQDN or YOUR name) []:10.98.33.136
Email Address []:jojan.paul@pearson.com

vi /etc/apache2/sites-available/default

<VirtualHost *:443>
        ServerAdmin webmaster@localhost
        ServerName 10.98.33.136:443
--------------
--------------
SSLEngine on
SSLCertificateFile /etc/apache2/ssl/apache.crt
SSLCertificateKeyFile /etc/apache2/ssl/apache.key
</VirtualHost>

Service apache2 restart

brose 10.98.33.136

It will prompt for This Connection is Untrusted and follow, I Understand the Risks-Add Exception-On Add Security-Exception window-Confirm Security Exception

It works!

Ref: https://www.digitalocean.com/community/tutorials/how-to-create-a-ssl-certificate-on-apache-for-ubuntu-14-04

Remove the apache2 in Ubuntu

To remove the apache2 service using Terminal:

First stop the apache2 service if it is running with:

sudo service apache2 stop

Now remove and cleanup all the apache2 packages with:

sudo apt-get purge apache2 apache2-utils apache2.2-bin apache2-common

run in case any other cleanup in needed

sudo apt-get autoremove 

You can do the following two tests to confirm apache has been removed:

which apache2
- should return a blank line

sudo service apache2 start 
apache2: unrecognized service

Installing WordPress Apache on RHEL

Download WordPress for apache
wget http://wordpress.org/latest.tar.gz

tar -xvzf latest.tar.gz -C /data

Configure MySQL Database

Connect to MySQL Server & Enter Password
mysql -u root -p
Enter password:

Creating New User for WordPress Database

CREATE USER wordpress@localhost IDENTIFIED BY "your_password_here";

Create New Database
create database wordpress;

Grant Privileges to Database
GRANT ALL ON wordpress.* TO wordpress@localhost;

FLUSH privileges
FLUSH PRIVILEGES;

exit

Configure Apache VirtualHost

vi /etc/httpd/conf/httpd.conf

<VirtualHost 10.33.68.27:80>
ServerAdmin test@test.com
DocumentRoot /data/wordpress
ServerName www.wordpresstest.com
        <Directory /data/wordpress>
        Options FollowSymLinks
        AllowOverride ALL
        </Directory>
</VirtualHost>

service httpd restart

vi /etc/hosts

127.0.0.1  wordpress

Configuring WordPress

cd /data/wordpress
cp wp-config-sample.php wp-config.php

vi wp-config.php

/** The name of the database for WordPress */
define('DB_NAME', 'wordpress');

/** MySQL database username */
define('DB_USER', 'wordpressuser');

/** MySQL database password */
define('DB_PASSWORD', 'Pearson1');

/** MySQL hostname */
define('DB_HOST', '10.161.141.36');

Open your browser and type any of the following address.

http://wordpress/
http://localhost
http://your-ip

Ref: http://www.tecmint.com/install-wordpress-using-lamp-or-lemp-on-rhel-centos-fedora/

Install Drupal 7 on Linux

Install the PHP 5.3.3 and Apache 2.2.15,

restart your apache server:
/etc/init.d/httpd restart

To function Drupal properly with apache and php

vi /etc/httpd/conf/httpd.conf
AddType application/x-httpd-php .html

vi /data/testphp.php
and enter this then save :

<?php
phpinfo();
?>

restart your apache server:

/etc/init.d/httpd restart

Configure Mysql to work with Drupal

Install MySQL-5.6

mysql -u root -p
mysql> CREATE DATABASE drupal;
mysql> CREATE USER drupaluser@localhost;
mysql> SET PASSWORD FOR drupaluser@localhost= PASSWORD('typepasswordhere');
mysql> GRANT ALL PRIVILEGES ON drupal.* TO drupaluser@localhost IDENTIFIED BY 'password';
mysql> quit

Finally lets start with Drupal

Get the latest package here : http://drupal.org/project/drupal

Copy the file to /data
and unpack it by typing :

tar -xvzf drupal-7.28.tar.gz
cd drupal-7.28
chmod a+w sites/default
cd sites/default
cp default.settings.php settings.php
chmod a+w settings.php
mkdir files
chmod a+w files

vi /etc/httpd/conf.d/vhost

<VirtualHost 10.10.xx.xxx:80>
    ServerName www.testsite.com
    ServerAlias testsite.com
    DocumentRoot "/data/drupal"
    DirectoryIndex index.php
    <Directory "/data/drupal">
        AllowOverride All
        Allow from All
        Options -Indexes
    </Directory>
</VirtualHost>

/etc/init.d/httpd restart

Add an entry in C:\Windows\System32\drivers\etc\hosts
10.10.xx.xxx www.testsite.com

Open up browser and go to :
http://www.testsite.com/drupal-7.28
it will open up a Drupal page !

To prevent unwanted users working on them..

chmod go-w settings.php
chmod 757 files

Ref: http://altinukshini.wordpress.com/2011/01/09/how-to-install-drupal-7-on-linux/

Set Up Replication in MySQL

MySQL replication is a process that allows you to easily maintain multiple copies of MySQL data by having them copied automatically from the main-server to a Replica-server database. This can be helpful for many reasons including facilitating a backup for the data, a way to analyze it without using the main database, or simply as a means to scale out.

For the process to work you will need two IP addresses: one of the main-server and one of the Replica-server.

10.10.0.39- main-server Database
10.10.0.40- Replica-server Database

User with Sudo privileges and have MySQL installed.

rpm -qa | grep MySQL
MySQL-client-5.6.12-1.el6.x86_64
MySQL-server-5.6.12-1.el6.x86_64
MySQL-devel-5.6.12-1.el6.x86_64
MySQL-shared-compat-5.6.12-1.el6.x86_64
MySQL-shared-5.6.12-2.el6.x86_64

Configure the Main-Server Database

Open up the mysql configuration file

vi /etc/my.cnf
bind-address = 10.10.0.39
log_bin = /data/var/lib/mysql/mysql-bin.log
binlog_do_db = newdatabase
server-id=1

service mysql restart

Grant privileges to the slave.

mysql -u root -p

mysql> GRANT REPLICATION SLAVE ON *.* TO '10.10.0.40'@'%' IDENTIFIED BY 'IctdscayK4blr';
Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

mysql> USE newdatabase;
Database changed

mysql> FLUSH TABLES WITH READ LOCK;
Query OK, 0 rows affected (0.01 sec)


mysql> SHOW MASTER STATUS;
+------------------+----------+--------------+------------------+-------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000032 |      523 | newdatabase  |                  |                   |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

The File and Position details are required while configuring slave.

mysqldump -u root -p --opt newdatabase > newdatabase.sql

mysql> UNLOCK TABLES;

mysql> QUIT;


Configure the Replica-Server Database

mysql -u root -p

mysql> CREATE DATABASE newdatabase;

mysql> QUIT;

Import the database that you previously exported from the main-server database.

mysql -u root -p newdatabase < /path/to/newdatabase.sql

vi /etc/my.cnf
#Slave
relay-log = /data/var/lib/mysql/mysql-relay-bin.log
log_bin = /data/var/lib/mysql/mysql-bin.log
binlog_do_db = newdatabase
server-id=2

service mysql restart

Enable the replication from within the MySQL shell.

mysql -u root -p

mysql> CHANGE MASTER TO MASTER_HOST='10.10.0.39',MASTER_USER='root', MASTER_PASSWORD='IctdsdkMSK4blr', MASTER_LOG_FILE='mysql-bin.000001', MASTER_LOG_POS=  523;
Query OK, 0 rows affected 2 warnings (0.01 sec)

The above step designates, (1) the current server as the slave of our main server. (2) It provides the server the correct login credentials. (3) Last of all, it lets the slave server know where to start replicating from; the main-server log file and log position come from the numbers we wrote down previously.

mysql> START SLAVE;

mysql> SHOW SLAVE STATUS\G;

mysql> QUIT;


If there is an issue in connecting, you can try starting slave with a command to skip over it:

mysql> STOP SLAVE;

mysql> SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1;

mysql> START SLAVE;

Ref :- digitalocean.com

Remove LVM Partitions in Linux

vi /etc/fstab
remove the present lvm entry.

lvremove /dev/VGdata/LVdata
Do you really want to remove active logical volume LVdata? [y/n]: y
  Logical volume "LVdata" successfully removed

vgremove VGdata
  Volume group "VGdata" successfully removed

pvremove /dev/sdb1
  Labels on physical volume "/dev/sdb1" successfully wiped

fdisk /dev/sdb

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): p

Disk /dev/sdb: 26.8 GB, 26843545600 bytes
64 heads, 32 sectors/track, 25600 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000b6891

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       25600    26214384   8e  Linux LVM

Command (m for help): d
Selected partition 1

Command (m for help): p

Disk /dev/sdb: 26.8 GB, 26843545600 bytes
64 heads, 32 sectors/track, 25600 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000b6891

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
You have new mail in /var/spool/mail/root

partprobe
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (Device or resource busy).  As a result,

it may not reflect all of your changes until after reboot.

reboot

Broadcast message from arao9aj@mb1utarmiweb01.pearsontc.com
        (/dev/pts/0) at 16:12 ...

The system is going down for reboot NOW!

Ref: http://www.linuxspy.com/1810/how-to-remove-lvm-partitions/

Change the default size of an inode

It is possible to define a non-standard sized inode by using the mke2fs tool with an undocumented option, -I. The size of the inode has to be a power of two and between the size of EXT2_GOOD_OLD_INODE_SIZE (128 bytes) and size of blocks in bytes. One reason for doing this could be that user is going to use extended attributes. Extended attributes are arbitrary name/value pairs used to store system objects like Access Control Lists (ACL). If the size of the inodes is larger than the default size, then sufficiently small attributes can be stored in inode

tune2fs -l /dev/mapper/VGdata-LVdata | grep Inode
Inode count:              1572864
Inodes per group:         8192
Inode blocks per group:   512
Inode size:               256

mke2fs -I 8192 /dev/mapper/VGdata-LVdata
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1572864 inodes, 6291456 blocks
314572 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
192 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000

Writing inode tables: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 35 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

tune2fs -l /dev/mapper/VGdata-LVdata | grep Inode
Inode count:              3276800
Inodes per group:         16384
Inode blocks per group:   1024
Inode size:               256

Ref: http://magazine.redhat.com/2007/04/23/how-can-i-change-the-default-size-of-an-inode-when-i-create-an-ext2ext3-filesystem/

Commonly Used Shell Variables

echo $BASH_VERSION --holds the version of this instance of bash
3.2.25(1)-release

echo $HOSTNAME --the name of the your computer
LinuxHost

echo $CDPATH --the search path for the cd command

echo $HISTFILE --the file in which command history is saved
/root/.bash_history

echo $HISTFILESIZE --the maximum number of lines contained in the history file
1000

echo $HISTSIZE --the number of commands to remember in the command history
1000

echo $HOME --the home directory of the current user
/root

echo $IFS --the Internal Field Separator

echo $LANG --used to determine the lang

echo $PATH --the search path for commands
/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

echo $PS1 --shows prompt settings
[\u@\h \W]\$

echo $TMOUT --the default timeout for the read builtin command

echo $TERM --the login terminal type
xterm
export TERM=vt100
export TERM=xterm

echo $SHELL --set path to login shell
/bin/bash

echo $DISPLAY --Set X display name
export DISPLAY=:0.1

export EDITOR=/usr/bin/vim --name of default text editor

Find out built in or an external command

type -a bind
bind is a shell builtin

type -a cat
cat is /bin/cat

type -a awk
awk is /bin/awk
awk is /usr/bin/awk

type -a true
true is a shell builtin
true is /bin/true

type -a select
select is a shell keyword