Admin Linux ... MySQL DBA

Most of time I face problem when I lose my bookmarks. Its important to take backup of bookmarks which easily transfer between systems. After doning 10min of search I comeup with 3 method. a. Export & Import Method. From the Firefox browser, click on on the "Bookmarks" menu located at the top of the window. Next, click on the "Organize Bookmarks" This brings you to a separate window which lists all existing bookmarks (favorite websites). From the File menu at the top, you have the option to Import and Export. If you need to import external bookmarks and merge them into Firefox, do so by clicking "Import" from the File menu. This allows you to import your favorites from Internet Explorer, or just an existing file you had saved in the past. Choose the desired option, and hit "Next" to search for your bookmarks. When done, click "Finish." If you need to externally save existing Firefox bookmarks, click on the "Export" option f

1. yum install php-pecl-apc If for some reason centosplus repo is not enabled then: 1. cd /usr/src/ 2. wget http://pecl.php.net/get/APC-3.0.19.tgz 3. tar xvzf APC-3.0.19.tgz 4. cd APC-3.0.19 5. yum install php-devel 6. yum install automake 7. yum install libtool httpd-devel* 8. /usr/bin/phpize 9. ./configure --enable-apc --enable-apc-mmap --with-apxs --with-php-config=/usr/bin/php-config 10. make 11. make install 12. ls /usr/lib64/php4/ or /usr/lib64/php/modules/ 13 #emacs /etc/php.ini extension=apc.so apc.enabled=1 apc.shm_segments=1 apc.shm_size=128 apc.ttl=7200 apc.user_ttl=7200 apc.num_files_hint=1024 apc.mmap_file_mask=/tmp/apc.XXXXXX apc.enable_cli=1

LVM terminology: a. Physical Volume (PV) : A PV is nothing more than a physical medium with some administrative data added to it - once you have added this, LVM will recognise it . b. Physical Extents (PE) :- Physical Extents are like really big blocks, often with a size of megabytes. c. Volume Group (VG) - A VG is made up of a number of Physical Extents (which may have come from multiple Physical Volumes or hard drives). While it may be tempting to think of a VG as being made up of several hard drives (/dev/hda and /dev/sda for example), it's more accurate to say that it contains PEs which are provided by these hard drives. d. Logical Volumes (LV) - A logical volume functions like a normal partition -- it have a filesystem such as Ext3, and a mount point. From , Volume Group, PEs can be assigned to a logical Volume (LV). Creating Physical volumes: #pvcreate /dev/sda3 Multiple physical volumes #pvcreate /dev/sda9 /dev/sda10 Creating a volume group: #vgcreate home2 /dev/sda3 Mult

1. Make these change in samba configuration file : emacs /etc/samba/smb.conf Important terms to understand a. wins support = yes b. domain master = yes c. netbios name = samba d. workgroup = OFFICE e. domain logons = yes 2. Samba root access #smbpasswd -a 3. Add new user : #useradd prabhat (adding linux user) #passwd prabhat #smbpasswd -a prabhat (converting linux user into samba user) 4. On the windows machine,Aadd window machine in 'OFFICE' domain of samba. On desktop, Right click on "My Computer" -> "properties" -> "Network identificatation" tab -> "change" while joing it will ask for username password "root" & "OFFICE" (see serial no 2.) Important Points: 1. There will be one and only one PDC over network. 2. The machine name must be unique over network. 3. While login from client domain name must be 'OFFICE' #emacs /etc/samba/smb.conf [global] log file = /var/log/s

Making NFS server Live: Server side (Server IP 10.1.31.1): 1. Check nfs-utils is installed or not using #yum list nfs-utils 2. Edit /etc/exports , add dir you want share with netrwork information and permision # vi /etc/exports /var/ftp/pub 10.1.0.0/16(rw,sync,no_root_squash) 3. Restart nfs service # service nfs retstart or # service nfs reload 4. Check port & shared dir using # rcpinfo -p # export -v # service portmap status Client Side (Client IP : 10.1.0.0/16, eg 10.1.31.67): 1. mount shared nfs folder # mount 10.1.31.3:/var/ftp/pub /mnt 2. Do static mount using /etc/fstab # vi /etc/fstab 10.1.31.1:/var/ftp/pub /mnt nfs defaults 0 0

Creating RAID-5 For this you need 3 Partition, 2 partitions with same size and 3rd partition is 10% greater than 1st or 2nd( since 1 & 2nd partition of same size. ). You can use fdisk command to create partition and make sure partition type must be FD. In fdisk command use option t to change partition type. eg. I have created /dev/sda1, /dev/sdb1 and /dev/sdc1. Once you created 3 partitions use this to make RAID 5: #mdadm --create /dev/md0 --level=5 --raid-device=3 /dev/sd{a1,b1,c1} Check the RAID partition using: #less /proc/mdstat Or you can see detail information's using: #mdadm --detail /dev/md0 To rebuild corrupted partation use: #mdadm /dev/md0 -r /dev/sdb0

Partition Creation for Swap filesystem 1. fdisk -l 2. fdisk /dev/sda 3. Type p & Press Enter 4. Type n & Press Enter 5. Just Press Enter for 1st Cylinder size 6. Type +sizeM for last Cylinder size 7. Type p & Press Enter 8. Type t & Press Enter 9. t2 /dev/sda12 10. Type 82 & Press Enter 11. Type p & Press Enter 12. Type w & Press Enter 13. partprobe 14. swapon -s 15. swapoff /dev/sda7 => Swapoff the another swap partition 16. swapon -s Creation of a new Swap Filesystem 1. mkswap -v1 /dev/sda12 2. swapon /dev/sda12 3. swapon /dev/sda7 Here /dev/sda7 & /dev/sda12 are swap partition. For automounting the either or swap partition do the following : 1. vi /etc/fstab 2. Add the following line :- /dev/sda12 swap swap defaults 0 0 Note :- Partition Id identifies what type of filesystem will have to create. Id

Linux partition using fdisk 1. fdisk -l => To check what type of Hard Disk i.e. Sata ( /dev/sda ) or Pata ( /dev/hda ) 2. fdisk /dev/sda 3. Type n then Enter => For new Partition 4. Just press Enter => For 1st Cylinder 5. Type +size and press Enter => For Last Cylinder for Example +1000M. Size can be in terms of M or K 6. Type p => To print the partition 7. Type w => To save the new partition. It's save in the hard disk but kernel partition table not updated. (/dev/sda11 is created in my system , might be different in your system) 8. Type partprobe & Press Enter => To update the kernel. 9. mkfs.ext3 -b 2048 /dev/sda11 => Here b is the block & is \block size in bytes & /dev/sda11 is new partition has created 11. e2label /dev/sda11

-> Openfire 1 . lynx http://www.igniterealtime.org/downloads/download-landing.jsp?file=openfire/openfire-3.4.5-1.i386.rpm 2 . rpm -ivh openfire-3.4.5-1.i386.rpm 3 . /etc/rc.d/init.d/openfire status 4 . /etc/rc.d/init.d/openfire start 5. Make sure that the firewall is stopped. 6 . http://www.grmtech.com:9090/ 7 . From the plugin tab in the web based admin control panel: installed Asterisk-IM Openfire -> Spark Download and install on client system. http://www.igniterealtime.org/downloadServlet?filename=spark/spark_2_5_8.exe -> web chat Go to plugin tab in the web based admin control panel: 1.Click on 'Available Plugins' 2. Install the following plugin a. Spark Fastpath Webchat b. Fastpath Service c. Monitoring Service (its is a optional)

1. turned on IP forwarding in sysctl.conf by setting the value to 1 2. gave the ip tables command for nat masquerade. iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE Checked that the commands took effect by: iptables-save and then made the entries from iptables-save inside the file /etc/sysconfig/iptables

# cat /proc/mdstat # mdadm -D /dev/md0 Detail : http://sitearticles.com/cms/show/43.html

ssh commands to log in without the password # ssh-keygen -t rsa * This will generate your id_rsa and id_rsa.pub in the .ssh directory in your home directory * copy the id_rsa.pub to the .ssh directory of the remote host you want to logon to as authorized_keys2 * If you have more than one host from which you want to connect to the remote host, you need to add the local host's id_rsa.pub as one line in the authorized_keys2 file of the remote host command for the 1and1 servers is: # scp .ssh/id_rsa.pub u35894953@217.160.226.69:./.ssh/authorized_keys2 :)

Redirect your all traffic: Case: example.com A record is point to server with IP10.1.31.7 (mean its resolves to IP 10.1.31.7 ), but you are running your web server from example.com on server with IP 10.1.31.8. So, you want all traffic coming to 10.1.31.7 will redirect to 10.1.31.8. Do the following changes on server have IP 10.1.31.7 : 1. Run apache . 2. Do the following entry in apache. a. NameVirtualHost 10.1.31.7 b <VirtualHost 10.1.31.7:80 > ServerName example.com ServerAlias www.example.com DocumentRoot /home/test ProxyRequests off ProxyPass / http://www.example.com/ ProxyPassReverse / http://www.example.com/ <Location /> ProxyPassReverse / </Location> </VirtualHost> 3. Do the following entry in /etc/hosts. 10.1.31.8 example.com 10.1.31.8 www.example.com ( make sure once you #ping example.com from 10.1.31.7 it resolver's to 10.1.31.8 ). Note: its redirect only http request not https. more you can see on this link

Removing all blank lines, leading and trailing blank spaces : #sed '/^$/d; s/^[ ]*//g; s/[ ]*$//g' prabhat.txt > kumar.txt This command will create new file (kumar.txt) on which it removes blank lines, leading and trailing blank spaces.

On production environment normal run level 3 is used and it get rarely changed. Runlevel and usage : 0 — Halt 1 — Single-user mode 2 — Not used (user-definable) 3 — Full multi-user mode 4 — Not used (user-definable) 5 — Full multi-user mode (with an X-based login screen) 6 — Reboot Check run level using :- # who -r or # runlevel Change run level using:- # telinit 5 or open file # emacs /etc/inittab Look for the default runlevel called initdefault which look like as follows: id: 3 :initdefault: Replace run level x with y ( where x is current run level and y you want to set ). Set services in run level using : # ntsysv or # chkconfig or # serviceconf

Putty stores its settings in the Windows registry. To save a backup of your Putty settings, you'll need to export this registry key to a file. HKEY_CURRENT_USER\Software\SimonTatham Steps : 1. Click Start->Run and type "RegEdt32" in the "Open" dialog. Click "Ok" 2. One RegEdt32 starts, you'll be presented with an application. 3. Press "Ctrl+F" to bring up the Find dialog. Enter the name of the key, "SimonTratham" in the "Find What" field, and make sure only "Keys" is checked in the "Look At" section of the dialog. Finally, click "Find Next" 4. The search may take a while, reminding us that the Windows Registry is a large and mysterious place where dragons be. Let's use these few seconds to reflect on the fact that you should never, ever, never change things in the registry unless you are absolutely, positively, totally, completely, 100% dead sure that you know exactly what you'r

$ cleanlinks this is supported on few flavor of Linux (XFree86), you can use this script. #/bin/bash DIR="$1" [ -d $DIR ] && [ $(ls -l $DIR | wc -l) -eq 1 ] && rmdir $DIR || : $ script.sh dir1

Using sed. $ sed '/^$/d' withblankline.txt > withoutblankline.txt Using grep. $ grep -v '^$' withblankline.txt > withoutblankline.txt Use following for loop (shell script) to remove all blank lines from all files stored in /home/prabhat/data directory: #!/bin/sh files="/home/prabhat/data/*.txt" for f in $files do sed '/^$/d' $i > $i.out mv $i.out $i done

The DNS is used to determine what IP address is associated with a given host name, so to reverse resolve a known IP address is to lookup what the associated host name for it. A reverse lookup is often referred to simply as reverse resolving, or more specifically reverse DNS lookups. Use of reverse DNS. Anti-spam Network troubleshooting Avoid spammers and phishers using a forward confirmed reverse DNS etc Check reverse DNS for given IP address under Linux or Windows XP/Server 2003. You can use standard UNIX / Linux utilities such as nslookup, dig or hosts to find out reverse DNS of a given IP address. eg; under Linux/UNIX/ $ host 66.65.123.34 or dig -x IP (66.65.123.34) and under Linux/UNIX/Windows nslookup 66.65.123.34

This is not a big thing, but sometime this small things matter a lot. You can put a message on remote ssh login for user or it will just act as a warning for a defaulters. Steps: 1. Open a file using : emacs /etc/motd and write a messge you want e.g. ******************************************************************** * * * This system is for the use of authorized users only. Usage of * * this system may be monitored and recorded by system personnel. * * * * Anyone using this system expressly consents to such monitoring * * and is advised that if such monitoring reveals possible * * evidence of criminal activity, system personnel may provide the * * evidence from such monitoring to law enforcement officials. * * * ******************************************************************** ========================================================== Unauthorized access to this machine is prohibited Press if you are not an authorized user 2. Save the file and exist. 3. Restart the ssh service usi