shell script , while loop

ykc · 03-30-2009, 06:42 AM

hi ,

i am trying a shell script, to wait until user enter's yes/no,
i am not getting out from while loop, what ever i enter including yes/no

Code:

echo 'do u want cont.. [yes/no]'
read yorn
while  [[ "$yorn" != "yes"  ||   "$yorn" != "no" ]]
do
echo 'do u want cont.. [yes/no]'
read yorn
echo 'u say '$yorn
done

eco · 03-30-2009, 07:00 AM

No shell righ now but here is how i'd do it

Code:

until [ ${yorn} != "yes" ] || [ ${yorn} != "no" ]; do
 echo 'do u want cont.. [yes/no]'
 read yorn
 $yorn=`echo ${yorn}|tr '[A-Z]' '[a-z]'`
 echo "u say $yorn"
done

You'll need to check the syntax but you get the idea.

Hko · 03-30-2009, 07:11 AM

For testing in "if", "while" and so, use single [ and ] (you had double: [[ ]]).
Use && instead of ||. You want the loop to run if the user did not enter "yes" AND did not enter "no".
When && or ||, you need to enclose both sides of it in '[' and ']'.

Fixed script: (changed line in bold)

Code:

#!/bin/bash

echo 'do u want cont.. [yes/no]'
read   yorn
while [ "$yorn" != "yes" ] && [ "$yorn" != "no" ]
do
    echo 'do u want cont.. [yes/no]'
    read yorn
    echo 'u say '$yorn
done

ykc · 03-30-2009, 07:30 AM

Hi

thanks eco,

I am very new to shell scripiting,
errors when i run code is

Code:

./dep_1.sh: line 1: [: !=: unary operator expected
./dep_1.sh: line 1: [: !=: unary operator expected
do u want cont.. [yes/no]
3
u say 3

& i am out from the loop,

i did some gusses to that code at line one but no use...

And thanks for using tr/translate, using tr looks good,

eco · 03-30-2009, 07:41 AM

As Hko said so well, we need double '[]' and we want '==' not '!='

So:

Code:

until [[ ${yorn} == "yes" ]] || [[ ${yorn} == "no" ]]; do

ykc · 03-30-2009, 07:50 AM

thnks Hko, it working