linux administration

Logical Volume Manager(LVM)- L.V.M(Logical Volume Manager) LVM is a method of allocating harddrive space into logical volumes that can be easily resized instead of partitions. With LVM the harddrive (or) set of harddrives are allocated to one or more physical volumes.  The physical volumes are combined into volume groups  Each volume group is divided into logical volumes which are assigned mountpoints such as /home and filesystem types such as ext3 To configure LVM -Create three LVM partitions -Convert them as physical volumes -Create volume groups from physical volumes -Create logical volumes from volume groups and assign mountpoints Implemention: fdisk -l #fdisk /dev/sda :n +500M :t <partition number> :8e    (Linux LVM) :w   (save & exit) #partx -a /dev/sda (update kernel) To convert LVM partitions as physical volumes #pvcreate /dev/sda<partition numbers> ex: pvcreate /dev/sda{9,10,11} To view physical volumes #pvdisplay To cre

<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script> <!-- Free shopping LOW COST --> <ins class="adsbygoogle"      style="display:inline-block;width:300px;height:250px"      data-ad-client="ca-pub-3647473415094616"      data-ad-slot="8200015080"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> Disk Quota - Disk Quota’s    Restricting a user or a group by creating files in a specific location.    Restricting a user or a group by the disk space in a specific location.      The idea behind quotas is that users are forced to stay under their disk consumption limit or with number of files in a particular location. Quota is handled on a per user, per file system basis. Quotas are of two types :    User level quotas      - usrquota    Group level quotas     - grpquota To apply userquota vi /etc/

Disk Partitions or Disk Management- Disk Management  All Existing Disk Partitions Using      fdisk -l fdisk -  command using the partitions you create a new partition, or modify an existing partition, you might want to view all available partition in the system. Use fdisk -l to view all available partitions as shown below.   device info will present under  /dev      ide ------------------   /dev/had     sata------------------   /dev/sda Creating a Partition [root@linuxadmin sysusers]# fdisk   /dev/sda Options-       m – To get  the help      p  -  To print the partition table      n  -  To create a Partition      d – To delete a   Partition      w  -  To save the modification      q  - To quit without save      n : for new partition Note- if we want to create a new primary partition already existing primary partitions will be deleted. so we will go for logical partitions        l : logical (we can't able to

Job Scheduling- As a system administrator some tasks are respective like backup. monitoring, log files.   To automate them below the commands or keys -at   -batch -crontab Crontab: to run some tasks automatically   to set a crontab for an user #crontab -e -u <user name> * * * * * /bin/echo "hello" A crontab file contains instructions to the cron deamon of the general form   "run this command at this time on this date" Cron examines entries once every minute Time mentioned here  field        allowed values  -----                   --------------  minutes               0-59  hour                  0-23  day of month     1-31  month               1-12 (or names, see below)  day of week      0-7 (0 or 7 is Sun, or use names)      A field may be an asterisk (*), which always stands for 'first-last’.        Ranges  of  numbers  are allowed.  Ranges are two numbers separated with a        hyphen.  The specified range is  inclusive

Sudo is super user  a concept which is used to specify a customized  privilege commands to non-privileged  users. All sudo configuration is located under /etc/sudoers file.       To edit sudo configuration file use visudo command.             Add users using useradd command                                                  #useradd   sree                                 #useradd   sinu                         #useradd   srini12                         #useradd   srin                         #useradd   srini            -Assign the passwords using passwd command.            -Open sudo configuration.                         #visudo  -f  /etc/sudoers        In any where type (Root access to srinui) srinu     All   = (All)   All where              srini   = Name of user to be allowed to use sudo            All =  Allow sudo access from any terminal (any Machine)      (All) = Allow sudo command to be executed as any use