Shell Scripting

Question 1

$?

Answer 1

• it gives the status of the last command executed

- if the command was successful, $? will contain 0, else a non-zero value

Question 2

What is Shell?

Answer 2

• it’s basically a command-line interface to the Unix system

- it is a medium provided to interact with the kernel, which is a CLI to the Unix system

Question 3

Types of Shells

Answer 3

• Bourne shell

- C shell

Question 4

Bash export

Answer 4

• it is a built-in command of the Bash shell

- it designates specified variables and functions to be passed to child-process

Question 5

> operator (right-angle bracket)

Answer 5

• output redirection
• redirect the output from a command typically into a file
• it overwrites any existing data in the file

Question 6

stdout

Answer 6

• the standard output

- it is usually the terminal window

Question 7

> > operator

Answer 7

• regular output append

- adds the output to the existing content instead of overwriting it

Question 8

What is a .sh file?

Answer 8

• Bourne shell script
• it is a computer program designed to be run by the Unix shell, a command-line interpreter
• Typical operations performed by shell scripts include file manipulation, program execution, and printing text.

Question 9

!/usr/bin/ksh

Answer 9

• a hashbang or shebang

- it tells Unix that this script should be run through the /bin/bash shell

Question 10

umask

Answer 10

• user file-creation mode

- it lets you set up default permissions for newly created files and folders