Amit's Blog

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

> cp -P

Xuggler uses ffmpeg to convert any media files to any media files. /usr/local/xuggler/bin/ffmpeg -y -threads 2 -i  source.avi -vcodec libx264 -fpre   video-high.ffpreset         ‘output.mp4’

e2label /dev/sdc1 /backupDisk

ls /sys/class/scsi_host replace the host below with the output of above command. echo "- - -" > /sys/class/scsi_host/<strong>host#</strong>/scan<br></br> fdisk -l<br></br> tail -f

Force Apache to use https : RequestHeader set X_FORWARDED_PROTO 'https'

Putty (Stores Session in a Folder ) [https://www.amitnepal.com/content/images/2011/08/ntputty.exe] Windows 7 Background Changer [https://www.amitnepal.com/content/images/2011/08/Win7LogonBackgroundChanger.exe]

Verify that sshd is not infected : strings /usr/sbin/sshd | grep %s:%s -A2 -B2 |head -3 If this outputs any file name, then check the filename if it has any passwords on that file. Verify that ssh, sftp etc.. are not infected : rpm -Vv openssh openssh-server openssh-clients | egrep -v

Tcp wrappers add an additional layer of security. Tcp Wrappers use two files namely : /etc/hosts.allow and /etc/hosts.deny hosts.allow file has precedence over hosts.deny . So it is a better idea to allow selectively in hosts.allow file and then deny all in the hosts.deny

> for user in $(cut -f1 -d : /etc/passwd); do crontab -u $user -l; done

rpm –import http://dev.centos.org/centos/RPM-GPG-KEY-CentOS-testing cd /etc/yum.repos.d wget http://dev.centos.org/centos/5/CentOS-Testing.repo yum install –disablerepo=* –enablerepo=c5-testing

Master – Master Replication Between two MySQL Servers The most important thing to consider in MySQL Master-Master replication is the auto increment field. In order to avoid getting data for a single field from both servers which breaks replication with the error message : duplicate entry. It is always good idea to