Interview Questions and Answers in Linux: Part-2

Linux:

• It's an open source.
• Free downloads and distribution/cheaper options.
• Lightweight with no need for high-end hardware.
• Users: Home users, developers etc.
• Ubuntu, Debian, Red-Hat, Solaris.
• installed on mobile phones, desktops, tablets video games consoles etc.

Unix:

• No source code for the general public.
• Not free, different prices for different variants.
• Need specific hardware, is comparatively costly.
• Mainly developed for mainframe servers and workstations except for OsX.
• AIX, HP-UX, BSD, Iris.
• Used internet servers, mainframes and high-end computers.

Kernel - Core part

System Library - Special functions using which application programs access Kernel features.

System Utility - Responsible for performing individuals and specialized functions.

• Users don't have root access.
• The virus can attack local files and folders only.
• All Linux accesses are recorded in log files.
• iptables to manage incoming and outgoing traffic.

• grep (Global Regular Expression Print)
• it is a search command; that uses pattern-based searches.
• Uses options and parameters specified along with the command line.

Ex: cat /etc/users/user.txt | grep -i 'basictechno'

the above command will print a line which contains only 'basictechno' as a string.

It's a live system admin's account.

Allows you to create and maintain user accounts and assign permissions.

The parent directory is represented by "/".

Contains all other directories and files.

The method of communication is insecure and The data is sent across the network without encryptions, in plain text format.

User - Owner/Creator of the file.

Group - All users in the group have the same permission.

Other - user with access to the file but not a part of that group.

Command: "chown"

Syntax: chown <newowner> <filename>

types of permissions for a file

• Read (r) - open and read
• Write (w) - modified content, renaming
• Execute (x) - executing file

Memory space comes into play when RAM doesn't have adequate memory to hold all executing programs.

Inactive memory pages are moved to swap space.

Soft mount case - if the NFS client fails to receive a response from NFS servers, it reports an error without waiting.

Hard mount case - NFS client repeatedly tries to contact the server until a response is received.