Playing with ISO image and CD drive. 1> create .iso file from cd #dd if=/dev/cdrom of=/mnt/rhel.iso Or #dd if=/dev/sr0 of=/mnt/rhel.iso i : input file o : output file create hard disk backup #dd if=/dev/sda of=/mnt/sdabackup 2> create iso file system…

Managing SELinux security Enhance Linux 2 types of security : DAC ( discrectionaly access control ) => rwx MAc ( mandatory access control ) => selinux There are two types in SELinux 1> Target : we use this 2> MLA…

Additional commands ====================================================================== 1> watch : it used to look refresh output of command. Refresh o/p defer 2 seconds. eg. #watch free -m ====================================================================== 2> Make the file size zero ( empty ) #echo > filename ====================================================================== 3> generate fake…

Backup/ Restore of file system or partition. #dump -ouf boot.dump /dev/vda1 Or /boot o : full backup u : update f : file Restore the dump backup #restore -rf boot.dump extra : need to install dump package and take backup…

Active crontal List ACL By using this you can set access (r,w,x) permission to particular group users on files 1> How to check current ACL on file #getfacl file.txt 2> set ACL on file #setfacl -m u:userName:rw-   file.txt   ——-m(modify), u(user)…

File Encryption and Decryption. Gnu PG stand for GNU privacy guard. and its GNU tool for secure connection and data storage. It use to encrypt data and create digital signature. To encrypt / decrypt file with password. use “gpg” command.…

Special Attributes It prevent delete, edit , rename option on file to root and all users 1> check current attributes #lsattr fileName.txt 2> set attributes #chattr +i filname.txt 3>Remove attributs #chattar -i filename.txt

Soft and Hard Link Soft link : 1. having diffent inode number for original and link file 2. if original file delete, soft link will not work. 3. one copy on hard disk 4. ln -s target Link_name Hard Link…

Users and group management. Three types of users 1> Super users (root) 2> System users : this users are created during system installation. 3> Limited users : these users are created ny root user and they have access to their…

Text processing and searching commands. ======================================================================= 1> more : page wise view of text. this is old command and give only down scrolling. #more filename ======================================================================= 2> less : It also provide page wise view. But give both up and…