How to validate that a parameter is an integer number in UNIX?

Question

I am writing a script where the second parameter must be an integer, but I don't know how to check if a parameter is an integer or not.

if test $2 =~ "^[0-9]+$"
 then
  echo "\nNumero  entero"
 else
  echo "\nError: El numero $2 no es un numero entero !!!\a"
 fi

aalazz · Accepted Answer · 2016-03-15T02:11:21.993

1

Almost. I'm assuming a bash shell:

#!/bin/bash
result=$(echo "$2" | grep '^[0-9][0-9]*$')
if [ -n "$result" ]
then
    echo 'Integer!'
else
    echo "Error: '$2' is not an integer"
fi

edited Mar 15 '16 at 02:11

answered Mar 15 '16 at 01:57

aalazz

D: It throws me this: grep: illegal option -- E Usage: grep -hblcnsviw pattern file . . . – Mac Mar 15 '16 at 02:04
1

and this? grep '^[0-9][0-9]*$' – aalazz Mar 15 '16 at 02:07
Now it works! Thanks a lot man... Hey but could you tell me what topic should I search to learn more about? – Mac Mar 15 '16 at 02:09
1

You should try to learn about the shell you're using. I assumed bash because it's the most common. For example: http://stackoverflow.com/questions/4651437/how-to-set-a-variable-equal-to-the-output-from-a-command-in-bash and, of course, the command "man grep" or any text about regular expressions – aalazz Mar 15 '16 at 02:15

1 Answers1