amit

print nth field using awk / cut echo 'This is a test' | awk '{print substr($0, index($0,$3))}' awk '{print substr($0, index($0,$3))}' <<< 'This is a test' echo 'This is a test' | cut -d '

Wget Tips & Tricks Download to a different folder : > wget -O /etc/yum.repos.d/CentOS-Testing.repo http://dev.centos.org/centos/5/CentOS-Testing.repo Download File with Authentication: > wget –http-user=Username –http-password=password  ‘url_to_download’ Using Curl : > curl –user $USERNAME ‘url’ Download with Rate Limited

dd if=/dev/zero of=/dev/sdc bs=512 count=1

Tar : Create a tar ball tar -cvf  tarfile.tar Extract from Tar tar -zxvf tarfile.tar Create Tar ball with compression tar -czvf tarfile.tar or tar -cjvf tarfile.tar Display Files inside a tarball: tar -tvf  tarball.tar Delete a single file from inside the tarball tar –delete  -f

**    Install Nagios on Centos** Download the latest version of nagios core and plugins from : http://www.nagios.org/download Install Pre-requisites: > yum install httpd gc glibc glibc-common gd gd-devel php Add user and group : > useradd -m nagios groupadd nagcmd usermod -a -G nagcmd nagios usermod -a -G nagcmd

Download Rootkit Hunter Here [http://downloads.sourceforge.net/project/rkhunter/rkhunter/1.3.8/rkhunter-1.3.8.tar.gz?r=http%3A%2F%2Fsourceforge.net%2Fprojects%2Frkhunter%2F&ts=1316446867&use_mirror=voxel] Untar and cd into the directory ./installer.sh –layout default –isntall rkhunter –update Now, you

Securing Server with Iptables Iptables is a great firewall when configured properly but sometimes you can lock yourself out with what you didn’t mean to. When you are starting to work on your firewall, it is always a good idea to create a cron job that will stop iptables

Blocking Ports in Iptables In order to block  a single port you can use the following statement : > iptables -A INPUT -p <protocol – udp or tcp>  –dport -j REJECT In order to block multiple ports , use the following statement : > iptables -A INPUT -p -m multiport –dports port1,

1. Copy the my-large.cnf which usually comes with mysql-server , usually inside the /usr/share/mysql  directory Note: you might want to backup your existing my.cnf before doing this. > cp -p /usr/share/mysql/my-large.cnf /etc/my.cnf Note: All values are in seconds for time and

Top Useful MySQL Variables, That you Might Want to Monitor Max_used_connections: Displays the maximum number of connection made at any instance of time. > mysql -p -e”show global status” | grep Max_used_connections Threads_connected: Indicates the total number of open connections to the server > mysql

There can be cases when you want to password protect the tar files. There are two ways you can do it. First Method Using SSL and Salt: Encrypt: > tar -cj directory | openssl des3 -salt > encrypted.tarfile Decrypt: > cat encrypted.tarfile | openssl des3 -d -salt |tar -xvj Second

Optimize A Table : mysql>optimize table ; Performance Tuning Parameters: > max_connections= 100 System RAM= Global Buffers + (Thread Buffers * max_connections) max_connections= (Available RAM – Global Buffers) / Thread Buffers Values for buffer sizes, lengths, and stack sizes are given in bytes unless otherwise specified. Typical Linux Installations can handle

net use * /d /y net use \server\share /d /y

To Create a 2M swap file ( 1024 * 2048M = 2097152) or this works as well bs = 1M count = 2048 dd if=/dev/zero of=/swapfile bs=1024 count=524288 mkswap /swapfile swapon /swapfile vi /etc/fstab /swapfile swap swap defaults 0 0

Margin Property : margin:  10px 5px 15px 20px; ( top , right, bottom, left )

> rm -rf  $(ls * | grep -v “directory or file to save”) In order to delete all files except multiple files you can do : > rm -rf $(ls * | egrep -v “foo|bar|test|”

* Mysql error – Got a packet bigger than ‘max_allowed_packet’ bytes **            In mysql console type the following :** `set global net_buffer_length=1000000;``` `set global max_allowed_packet=10000000000000;``` and then import as : mysql -u root -p --max_allowed_packet=1000M < dbdump.sql * Cannot load from mysql.proc. The

./configure –with-mysql=/usr/bin/ –with-libdir=lib64

> for i in *.dump; do mv  “$i” “${i/.dump}”;done for i in *.JPG; do mv "$i" "${i/.JPG}".jpg; done

Cd in to your svn repository path and create and run this script #!/bin/bash<br></br> for i in *<br></br> do<br></br> if [ "${i}" != "backupsvn.sh" ]; then<br><

./configure  –prefix=/usr –sysconfdir=/etc –with-config-file-path=/etc/ –localstatedir=/var –with-apxs2 –with-openssl –with-zlib –enable-calendar –with-gd –with-jpeg-dir=/usr/lib –with-png-dir=/usr/lib –with-imap –with-imap-ssl –with-kerberos –enable-sysvsem –enable-sysvshm –enable-sockets –with-curl –enable-mbstring –with-mcrypt –with-mysql –with-mysqli –with-gettext –with-freetype-dir –enable-gd-native-ttf

You  need to have a package phpize in order to compile an additional module. If you dont have phpize,  you need to install php-devel . When you install php from source.. you should get the phpize package. Go to the directory where you have the extensions. eg. /usr/src/php-5.2.

> ./configure –prefix=/usr –sysconfdir=/etc –localstatedir=/var –disable-largefile –with-charset=utf8 –with-unix-socket-path=/var/lib/mysql/mysql.sock –with-mysqld-user=mysql –with-zlib-dir=/usr –without-debug –with-ssl –with-ndbcluster –without-ndb-debug –with-extra-charsets=gb2312