Linux Administrator Interview Questions And Answers

Linux libraries contain pre-written code that a developer can reuse in their applications.
Your company purchased 5 new laptops. Laptop have Intel core i3 processor and Window 8 installed. Your network admin wants to install RHEL on them, but is concerned that it cannot be done because they already have Window 8 installed. Can this be done?
Yes you can install any operating system as long as the hardware is compatible. Hardware and operating systems are modular. Computer hardware is not tied in any way to a particular OS. Every OS have some minimum hardware requirements, if your hardware meets with that requirements, you can install that OS.
You are a network administrator, your company wants you to download the source code of latest Linux kernel for the developer team. Can you do this?
Source code of Linux kernel is available under the GPL license. Under the GPL, you are free to download the Linux source code and modify it.
Your company have less funds but need a reliable file server set up? Which OS and file server service can you use ?
Use Linux operating with NFS file service.
You have purchased new laptop and want to resell old one, but you don't want to violate any licensing for OS. What can you do to avoid violating a software license?
You can install Linux OS. All major software's for Linux are available under the GPL, those you can use without violating any software license.

Squid service can be used to turn any Linux system into an in proxy server.

MySQL and PostgreSQL are Linux database server.

NFS service is used to provide file sharing.

CUPS provide network printing between Linux systems. It can be used with Samba service to extend network printing to windows systems.

Linux was originally created to run on the Intel x86 platform.

GPL stands for General Public License and it was created to protect the intent of the GNU project.

The Linux kernel is released under the GNU General Public License version 2 (GPLv2), and is developed by contributors worldwide.

GNU project was initiated by Richard Stallman on 27 September 1983 at MIT. Main motive of this project was to give freedom and control in use of software's. GNU software guarantees these freedom-rights legally via its license. Users are free to run the software, share it, copy it, distribute it, study it and modify it.

Linux kernel was built to work like UNIX but doesn't use any of the UNIX code-this is why Linux is not UNIX. A kernel is the core of any operating system.

POSIX stands for Portable Operating System Interface for Computer Environments. It is the standard for ensuring compatibility between UNIX versions.

In 1991 Linus Torvalds, a 21-year-old student at the University of Helsinki Finland posted the source code of Linux kernel on the Internet and invited other programmers to modify and enhance it.

Minix is the UNIX clone written by Andrew Tanenbaum at VU University, in Amsterdam when universities were no longer allowed access to the UNIX source code. MINIX also inspired the creation of the Linux kernel.

Load Average is defined as the average sum of the number of process waiting in the run queue and number of process currently executing over the period of 1,5 and 15 minutes. Using the 'top' and 'uptime' command we find the load average of a linux sever.

By using the command 'find /<directory -type f'.

/var/lib/puppet/ssl/ca/signed

puppetca -sign hostname-of-agent' in (2.X) & 'puppet ca sign hostname-of-agent' in (3.X)

Manifests, in Puppet, are the files in which the client configuration is specified.

Puppet is an open-source & enterprise software for configuration management toll in UNIX like operating system. Puppet is a IT automation software used to push configuration to its clients (puppet agents) using code. Puppet code can do a variety of tasks from installing new software, to check file permissions, or updating user accounts & lots of other tasks.

To Set the kernel parameters in linux , first edit the file '/etc/sysctl.conf' after making the changes save the file and run the command 'sysctl -p' , this command will make the changes permanently without rebooting the machine.

We can find the WWN numbers of HBA cards using the command 'systool -c fc_host -v | grep port_name'

There are two ways to scan newly assigned luns :
Method 1: if sg3 rpm is installed , then run the command 'rescan-scsi-bus.sh'
Method 2: Run the Command , echo " - - - " > /sys/class/scsi_host/hostX/scan

We should never upgrade Linux Kernel , always install the new New kernel using rpm command because upgrading a kenel can make your linux box in a unbootable state.

We can enable a service using the Command 'chkconfig <Service-Name> on -level 3′

With the help of command 'chkconfig -list | grep 5:on' we can list all the service that are enabled in run level5. For other run levels just replace 5 with the respective run level.