Most Asked Linux Interview Questions and Answers
What are symbolic links?
Symbolic links act similarly to shortcuts in Windows. Such links point to programs, files or directories. It also allows you instant access to it without having to go directly to the entire pathname.
What is the pwd command?
The pwd command is short for print working directory command. It’s counterpart in DOS is the cd command, and is used to display the current location in the directory tree.
How do you insert comments in the command line prompt?
Comments are created by typing the # symbol before the actual comment text. This tells the shell to completely ignore what follows. For example: “# This is just a comment that the shell will ignore.”
What is a swap space?
A swap space 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.
Does the Ctrl+Alt+Del key combination work on Linux?
Yes, it does. Just like Windows, you can use this key combination to perform a system restart. One difference is that you won’t be getting any confirmation message and therefore, reboot is immediate.
What are daemons?
Daemons are services that provide several functions that may not be available under the base operating system. Its main task is to listen for service request and at the same time to act on these requests. After the service is done, it is then disconnected and waits for further requests.
What is command grouping and how does it work?
You can use parentheses to group commands. For example, if you want to send the current date and time along with the contents of a file named OUTPUT to a second file named MYDATES, you can apply command grouping as follows: (date cat OUTPUT) > MYDATES
What is the advantage of open source?
Open source allows you to distribute your software, including source codes freely to anyone who is interested. People would then be able to add features and even debug and correct errors that are in the source code. They can even make it run better, and then redistribute these enhanced source code freely again. This eventually benefits everyone in the community.
How do you refer to the parallel port where devices such as printers are connected?
Whereas under Windows you refer to the parallel port as the LPT port, under Linux you refer to it as /dev/lp . LPT1, LPT2 and LPT3 would therefore be referred to as /dev/lp0, /dev/lp1, or /dev/lp2 under Linux.
How do you switch from one desktop environment to another, such as switching from KDE to Gnome?
Assuming you have these two environments installed, just log out from the graphical interface. Then at the Log in screen, type your login ID and password and choose which session type you wish to load. This choice will remain your default until you change it to something else.
How do you execute more than one command or program from a single command line entry?
You can combine several commands by separating each command or program using a semicolon symbol. For example, you can issue such a series of commands in a single entry:
ls –l cd .. ls –a MYWORK which is equivalent to 3 commands: ls -l cd.. ls -a MYWORK
**Note that this will be executed one after the other, in the order specified.
What are the basic components of Linux?
Just like any other typical operating system, Linux has all of these components: kernel, shells and GUIs, system utilities, and application program. What makes Linux advantageous over other operating system is that every aspect comes with additional features and all codes for these are downloadable for free.
Are drives such as harddrive and floppy drives represented with drive letters?
No. In Linux, each drive and device has different designations. For example, floppy drives are referred to as /dev/fd0 and /dev/fd1. IDE/EIDE hard drives are referred to as /dev/hda, /dev/hdb, /dev/hdc, and so forth.
What are the kinds of permissions under Linux?
There are 3 kinds of permissions under Linux:
– Read: users may read the files or list the directory
– Write: users may write to the file of new files to the directory
– Execute: users may run the file or lookup a specific file within a directory
Write a command that will look for files with an extension “c”, and has the occurrence of the string “apple” in it.
Find ./ -name “*.c” | xargs grep –i “apple”