Linux Format forums

siggij · Joined: Wed Aug 23, 2006 10:14 pm Posts: 5

Having trouble with the if statement. Can anybody help please?

#!/bin/bash
while true
do
echo -n "Enter a number between 20 and 30: "
read answer
if [ "$answer" >= 20 || "$answer" <= 30 ]
then
echo "Right answer"
exit 0
else
echo "Wrong answer"
continue
fi
done

bobthebob1234 · Posted: Mon Mar 07, 2011 1:16 am Post subject:

No expert with bash but :
http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_01.html

and

http://www.linuxconfig.org/Bash_scripting_Tutorial

would suggest you want -le and -ge
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nelz · Posted: Mon Mar 07, 2011 9:10 am Post subject:

It's hard to suggest a solution to a problem you haven't stated. What's the script supposed to do? What is it actually doing? Have you tried it with bash -x scriptname (or added set +x to the start of the script)? And why have you got a continue statement at the end of a loop, when all it can d is continue anyway.
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siggij · Joined: Wed Aug 23, 2006 10:14 pm Posts: 5

I'm just trying to learn bash scripting, basically. The script is supposed to give a right answer if you enter a number between 20 and 30 including. Everyting else gives an error. Thought the code would speak for itself. I know the if statement is wrong, dont need further error detection, but set +x is a good idea anyway. I'm trying to have just one if statement something like 'if [ "$answer" -ge 20 -o -le 30 ]' but it doesnt work. They work seperatealy though. I think bash is more advanced than having a seperate if statement for every comparison. Good to know I dont need continue, I learned something new. Thanks! But the problem is not resolved.

MartyBartfast · Posted: Mon Mar 07, 2011 2:17 pm Post subject:

both || and -o are logical OR, you need a logical AND, if the answer is ge 20 AND the answer is le 30 then it's OK, so the line you need is something like

nelz · Posted: Mon Mar 07, 2011 2:23 pm Post subject:

Why don't you post the actual error? That way we can look for a solution to the problem, rather than trying to guess what the problem is.
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Unix is user-friendly. It's just very selective about who it's friends are.

siggij · Joined: Wed Aug 23, 2006 10:14 pm Posts: 5

Thanks MartyBartfast you nailed it Smile

Why are so many of you irritated? Its a huge turnoff (no sex involved).

Best regards,
Siggi
Iceland

MartyBartfast · Posted: Mon Mar 07, 2011 8:33 pm Post subject:

nelz · Posted: Mon Mar 07, 2011 10:03 pm Post subject:

siggij · Joined: Wed Aug 23, 2006 10:14 pm Posts: 5

Im truly sorry if I was offensive, I'm just feeling vulnerable right now. Thanks for the help, guys. And thanks to nelz for the rules of engagement. I will try to follow it to my heart's content from now on.

Peace,
Siggi

nelz · Posted: Tue Mar 08, 2011 1:17 am Post subject:

You weren't being offensive, you were only hurting yourself. The only person that stands to gain from others being able to answer your question is you, so it is in your best interests to give sufficient information for them to be able to do so - rather than having to make wild guesses as to what may be wrong.
_________________
Unix is user-friendly. It's just very selective about who it's friends are.