Math in Shell Scripts

One thing that often confuses new users to the Unix / Linux shell, ishow to do (even very simple) maths. In most languages, x = x + 1 (oreven x++) does exactly what you would expect. The Unix/Linux shell isdifferent,however. It doesn’t have any built-in mathematical operatorsfor variables. It can do comparisons, but maths isn’t supported, noteven simple addition. Shell script variables are by default treated as strings,not numbers,which adds some complexity to doing math in shell script. To keep withscript programming paradigm and allow for better...

Shell Script to Generate Fibonacci Series

By definition in mathematics, the Fibonacci Numbers are the numbersin the below sequence:0,1,1,2,3,5,8,13,21,34,55,89,144, ...... By definition, the first two Fibonacci numbers are 0 and 1, and eachsubsequent number is the sum of the previous two. Some sources omitthe initial 0, instead beginning the sequence with two 1s. In mathematical terms, the sequence Fn of Fibonacci numbers is defi-ned by the recurrence relation Fn = Fn-1 + Fn-2,with seed values F0 = 0 and F1 = 1.Iterative Method: #!/bin/bash#!/bin/bash# SCRIPT: fibo_iterative.sh#...

Shell Script to Find Armstrong Numbers Between a Given Range

#!/bin/bash# SCRIPT: armstrong_bw_range.sh# USAGE: armstrong_bw_range.sh# PURPOSE: Finding Armstrong numbers between given range.# \\\\ ////# \\ - - //# @ @# ---oOOo-( )-oOOo---#Armstrong numbers are the sum of their own digits to the power of#the number of digits. As that is a slightly brief wording, let me#give an example:#153 = 1³ + 5³ + 3³#Each digit is raised to the power three because 153 has three#digits. They are totalled and we get the original...

Shell Script to Check Armstrong Number

#!/bin/bash# SCRIPT: armstrongnumber.sh# USAGE: armstrongnumber.sh# PURPOSE: Check if the given number is Armstrong number ?# \\\\ ////# \\ - - //# @ @# ---oOOo-( )-oOOo---# Armstrong numbers are the sum of their own digits to the power of# the number of digits. As that is a slightly brief wording, let me# give an example:# 153 = 1³ + 5³ + 3³# Each digit is raised to the power three because 153 has three# digits. They are totalled and we get the original...

Decimal to Binary Conversion Shell Script

#!/bin/bash# SCRIPT: dec2binary.sh# USAGE: dec2binary.sh Decimal_Number(s)# PURPOSE: Decimal to Binary Conversion. Takes input as command line# arguments.# \\\\ ////# \\ - - //# @ @# ---oOOo-( )-oOOo---####################################################################### Script Starts Here ######################################################################if [ $# -eq 0 ]then echo "Argument(s)...

Binary to Decimal Conversion Shell Script

#!/bin/bash# SCRIPT: binary2dec.sh# USAGE: binary2dec.sh Binary_Numbers(s)# PURPOSE: Binary to Decimal Conversion. Takes input as command line# arguments.# \\\\ ////# \\ - - //# @ @# ---oOOo-( )-oOOo---####################################################################### Script Starts Here ######################################################################if [ $# -eq 0 ]then echo "Argument(s)...

How to Validate Integer Input using Shell script

Method 1:#!/bin/bash# SCRIPT: validinteger.sh# USAGE: validinteger.sh [ Input value to be validated ]# PURPOSE: validate integer input, allow negative integers also## \\\\ ////# \\ - - //# @ @# ---oOOo-( )-oOOo---## Using the $? exit status variable or integer comparison operators, a# script may test if a parameter contains only digits, so it can be# treated as an integer.####################################################################### Arguments Checking ...