Shell Script to find factorial of a number using Recursion

Q. How do I find factorial of a number using recursion function in Bash

Ans:

#!/bin/bash
#Recursive factorial function
factorial()
{
local=$1
if((local<=2)); then
echo $local
else
f=$((local -1))
#Recursive call
f=$(factorial $f)
f=$((f*local))
echo $f
fi
}
#main script
read -p "Enter the number:" n
if((n==0)); then
echo 1
else
#calling factorial function
factorial $n
fi

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Shell Script to find "a" to the power "b" using function

Q. How do I write Shell Script function to find "a" to the power "b"

Ans.

#!/bin/bash
#function to find "a" to the power "b"
power()
{
num=$1
pow=$2
counter=1
result=1
if((pow==0)); then
result=1
fi
if ((num==0)); then
result=0
fi
if((num>=1&&pow>=1)); then
while((counter<=pow))
do
result=$((result*num))
counter=$((counter + 1))
done
fi
#Printing the result
echo "$1 to the power $2 is $result"
}

#main script
read -p "Enter number:" num
read -p "Enter power:" pow

#calling above function
power $num $pow

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Shell Script to reverse a String

Q: How do I reverse a string in Linux/Unix?

Ans:

#!/bin/bash
read -p "Enter string:" string
len=${#string}
for (( i=$len-1; i>=0; i-- ))
do
# "${string:$i:1}"extract single single character from string.
reverse="$reverse${string:$i:1}"
done
echo "$reverse"

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Shell Script to Print Fibonacci Series

Q. How do I print fibonacci series in Bash

Ans:

#!/bin/bash
c=0
a=1
b=1
read -p "Enter limit of fibonacci Series:" n
echo -n "$a "
echo -n "$b "
#Fibonacci series logic
while((c<n))
do
c=$((a+b))
echo -n "$c "
a=$b
b=$c
done
echo -e "\n"

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