Shell program to read a number and reverse the number

in Categories Academic, Shell Math last updated April 8, 2008
#!/bin/bash
# Shell program to read a number and reverse the number
# for example 123 should output as 321
# -----------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
 
echo -n "Enter number : "
read n
 
# store single digit
sd=0
 
# store number in reverse order
rev=""
 
# store original number
on=$n
 
# use while loop to caclulate the sum of all digits
while [ $n -gt 0 ]
do
    sd=$(( $n % 10 )) # get Remainder 
    n=$(( $n / 10 ))  # get next digit
    # store previoues number and current digit in rev
    rev=$( echo ${rev}${sd} ) 
done
 
echo  "$on in a reverse order $rev"

Shell program to calculate the number of digits in a number read from the user

in Categories Academic, Shell Math last updated April 8, 2008
#!/bin/bash
# Shell program to calculate the number of digits in a
# number read from the user
# -----------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
 
echo -n "Enter number : "
read n
 
sd=0
 
# store number of digit 
nd=0
on=$n # store $n so that we can use it later
 
# use while loop to caclulate the number of digit
while [ $n -gt 0 ]
do
    sd=$(( $n % 10 )) # get Remainder 
    n=$(( $n / 10 )) 
    nd=$(( $nd + 1)) # calculate all digit in a number till n is not zero
done
echo  "Numnber of digit in a $on is $nd"

Shell script to read a character (upper or lower), digit, special symbol and display message according to the character entered

in Categories Decision Making last updated April 5, 2008

This script uses sed command to find out all digits or upper characters. -z string (conditional expression) will return true if the length of string is zero.

Script logic

Read one character
[1] Use sed command to determine input character is digit or not (sed -e ‘s/[A-Z]//g’))

[2] Attempt to match regex [0-9] i.e. all digit against the pattern space

[3] If successful, replace that portion matched with replacement // i.e. do nothing.
If digits are in input, it will replace all those digit, and if input is only digit, nothing is left i.e. string is zero and that is what tasted with -z conditional expression.

#!/bin/bash
# Shell script to read a character (upper or lower), digit, special symbol and
# display message according to the character entered
# -----------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
 
char=""
echo -n "Enter a one character : "
read char
# use sed command to determine input character is digit or not
# -e : start script
# s/[0-9]// : Attempt to match regex [0-9] i.e. all digit against the pattern space (echo $char).
# If  successful,  replace  that  portion  matched  with replacement i.e. // do nothing. 
# g : Global replacement
# so if digit are in input it will replace all those digit, and if input is only digit, nothing
# is left i.e. string is zero and that is what tasted with -z
if [ -z $(echo $char | sed -e 's/[0-9]//g') ]
then
	echo "$char is Number/digit"
elif [ -z $(echo $char | sed  -e 's/[A-Z]//g') ] # find out if character is upper
then
        echo "$char is UPPER character"
 
elif [ -z $(echo $char | sed -e 's/[a-z]//g') ] # find out if character is lower
then
        echo "$char is lower character"
else
	echo "$char is Special symbol" # else it is special character
fi