JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2022 LINUX PROGRAMMING Previous Question Paper (March/April - 2022 - R17)

To calculate the factorial of a number in a shell script, you can use a loop structure to multiply the sequence of integers from 1 to the input number.

#!/bin/bash
echo "Enter a number:"
read num
fact=1
if [ $num -lt 0 ]; then
  echo "Factorial does not exist for negative numbers."
else
  for (( i=1; i<=num; i++ ))
  do
    fact=$((fact * i))
  done
  echo "Factorial of $num is $fact"
fi

Shell Meta Characters are special characters that have a specific meaning to the shell, rather than being treated as literal text. They are used for pattern matching, redirection, and command control. Examples include:

• *: Matches any string of characters.
• ?: Matches any single character.
• > and <: Used for input/output redirection.
• |: Pipes the output of one command to the input of another.
• ;: Separates multiple commands on a single line.

Shell Variables are used to store data within the shell environment. They are typically defined using the syntax VARIABLE_NAME=value. Variables can be local, existing only within the current shell, or environment variables, which are exported to child processes using the export command. To access the value stored in a variable, the $ prefix is used (e.g., echo $HOME). Variables are essential for script configuration, path management, and storing temporary results during execution.