Comments on UNIX/Linux Bash Shell Scripting: How to Validate Integer Input using Shell script

Samples: Test numeric 'foo' No: foo Test n...

2011-11-23T16:23:06.332-08:00

Samples:
Test numeric 'foo'
No: foo
Test numeric '2'
Yes: 2
Test numeric '-7'
Yes: -7
Test numeric '+8'
Yes: 8
Test numeric '2**7'
Yes: 128
Test numeric '3+4+5'
Yes: 12
Test numeric '20%14'
Yes: 6
Test numeric '+'
No: +
Test numeric '-'
No: -
Test numeric '%'
No: %

the ultimate numeric testing: #!/bin/bash n=&quo...

2011-11-23T16:19:03.584-08:00

the ultimate numeric testing:

#!/bin/bash

n="$1"

echo "Test numeric '$n' "
if ((n)) 2>/dev/null; then
n=$((n))
echo "Yes: $n"
else
echo "No: $n"
fi

From Method 1, how would I adapt if [ $Number -ne...

2011-03-30T05:17:32.031-07:00

From Method 1, how would I adapt

if [ $Number -ne 0 -o $Number -eq 0 2>/dev/null ]

so that it worked in a while loop so that I could keep prompting the user for a number until they entered one?

Hi Bond, Your idea is good, but above script has ...

2011-01-07T08:03:31.045-08:00

Hi Bond,

Your idea is good, but above script has a mistake.

$ sh validintegernum.sh -12-12

Script to validate whether input is an Integer value of not
code: 45
code: 49
code: 50
code: 45
code: 49
code: 50

The input is valid integer value

It accepts hyphen any where. I rectified it and posted as method 3.

Hi Venu, Just another version to server the same ...

2011-01-03T01:57:29.321-08:00

Hi Venu,

Just another version to server the same purpose using comparison with ASCII chart:

#!/bin/bash

echo -e "\nScript to validate whether input is an Interger value of not"

if [ $# -ne 1 ]
then
echo "Usage: $0 [Input Value to be validated]"
exit
fi

str="$1"
cnt=${#str} # Counting the length of string fetched

for ((i=0; i < cnt; i++))
do
char=${str:$i:1} # Reading one character at a time from the input string

code=`printf '%d' "'$char"` # Echo the ASCII value of character

echo "code: " $code
if [ $code -lt 48 ] || [ $code -gt 57 ] # Comparing the ASCII value range of Intergers ( 48 - 57 )
then
if [ $code -ne 45 ] # To accept the negative integer value as well
then
echo -e "Input is not an integer value\n"
exit
fi
fi
done

echo -e "\nThe input is valid integer value\n"