1.How to check which OS version is installed on Server ?
Ans: #cat /etc/os-release command can be used to view Linux OS details.
2. How to check the ip address of LAN Card ?
Ans:#ip a or #ifconfig command can be used to view the Ip address details.
3.Command to view the kernel version in Linux?
Ans:#uname -r command helps us to view the kernel version in linux.
4.What is soft link and hard link?
Ans: Soft link is a method to create short cuts in Linux. It is similar to the windows short cut feature. Hardlink cannot be created for directories. Hard link can only be created for a file. If you remove the hard link or the symlink itself, the original file will be deleted, whereas in softlink only the shortcut will be deleted.
5.What are the run levels in Linux and how to change them?
There are 7 different run levels present (run level 0-6) in Linux system for a different purpose. The descriptions are given below.
0: Halt System (To shutdown the system)
1: Single user mode
2: Basic multi user mode without NFS
3: Full multi user mode (text based)
5: Multi user mode with Graphical User Interface 6: Reboot System
To change the run level, edit the file “/etc/inittab” and change initdefault entry ( id:5:initdefault:). If we want to change the run level on the fly, it can be done using ‘init’ command.
6.What is the command to view memory details?
Ans: #free -g command will provide you the physical and swap memory details in gigabytes.
7.What is the default uid & gid of root user ?
Ans: Default uid & gid of root user is 0.
8.What is the command to view the process running?
Ans:#top or htop are the commands used to view the process running.
9.How to stop the process?
Ans:#kill -9 pid to know the process id(PID) you can run the command #ps -aux | grep process name to get the process id.
10.what is the command to view the opened files in Linux?
Ans:#lsof is the command to view the opened files in Linux.
11.What is a swap memory and how much to be allotted?
Swap memory is a certain amount of space used by Linux to temporarily hold some programs that are running concurrently. This happens when RAM does not have enough memory to hold all programs that are executing. Swap memory size should be double the size of physical RAM.