UNIX Basics

“ls” command in UNIX

• Lists the files in a directory

• Compare the size of two files

• Gives the currently logged session details

• Compares two numerals and prints the lower value

Answer explanation

“ls” command in UNIX lists all the contents in a directory. Ls can be used with many options to display additional details

Which among the following is not a part of UNIX operating system

• Programs

• Libraries

• Kernel

• Shell

Answer explanation

The UNIX operating system is made up of three parts; the kernel, the shell and the programs

In UNIX, the shell act as an interface between user and

• Kernel

• Operating System

• Hardware

• Programs

Answer explanation

The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell. The shell is a command line interpreter (CLI). It interprets the commands the user types in and arranges for them to be carried out.

Everything in UNIX is

• None

• a Process

• a file or a process

• a File

Answer explanation

Everything in UNIX is either a file or a process. A process is an executing program identified by a unique PID (process identifier). A file is a collection of data. They are created by users using text editors, running compilers etc.

Which command is used for changing directory in UNIX?

• mkdir

• cd

• chgdir

• cddir

Answer explanation

The command cd directory means change the current working directory to ‘directory’. The current working directory may be thought of as the directory you are in, i.e. your current position in the file-system tree.

In UNIX, file permissions are not set for

• User

• Other users

• Devices

• User Groups

Answer explanation

Every directory and file on the system has an owner, and also an associated group. It also has a set of permission flags which specify separate read, write and execute permissions for the ‘user’ (owner), ‘group’, and ‘other’ (everyone else with an account on the computer)

In Unix, how can you read the manual – help pages – about a command

• Type ‘help’ and the command

• Type ‘options’ and the command

• Type ‘details’ and the command

• Type ‘man’ and the command

Answer explanation

To see what all a Linux command can do, type “man ”. This will show you the manual of the specified

Which is the most common text editor in UNIX ?

• Visual editor

• notepad

• word

• openoffice

Answer explanation

The default editor that comes with the UNIX operating system is called vi (visual editor). Alternate editors for UNIX environments include pico and emacs, a product of GNU.

You have created a shell script and wants to run the script. What should you do before trying to run the script ? 

• No action required

• Compile the script to create the executable

• Update the execute permission of the script

• Give ownership of the file to system admin

Answer explanation

You have to update the execute permission of the script using the command ‘chmod’

Which is valid mode of operation in vi editor ?

• Typing mode

• Command Mode

• Append mode

• Open mode

Answer explanation

The UNIX vi editor has two modes of operation:1.Command mode commands which cause action to be taken on the file, and2.Insert mode in which entered text is inserted into the file.In the command mode, every character typed is a command that does something to the text file being edited; a character typed in the command mode may even cause the vi editor to enter the insert mode. In the insert mode, every character typed is added to the text in the file; pressing the (Escape) key turns off the Insert mode.