checking two conditions using while loop in bash script

Question

I want to check if the user has not entered 'y' or 'n' and if not then to keep looping asking the user to entered the correct letter but it is not working... the code below shows what I have tried so far ....can someone help me please???

echo "Enter 'y' to exit or 'n' to continue" 
echo -n "Do you want to exit? "
read character

while [ "$character" != "y" || "$character" != "n" ];
do

    echo -n "Wrong key re-enter 'y' to exit or 'n' to continue"
    read character
done

$var != y || $var != n is always true. Anything that isn't y will make the first part true and y will make the second part true. — Etan Reisner
– Etan Reisner, Commented Feb 4, 2015 at 22:47
Think about the logic of what you are trying to test. Do you want $var is not x OR not y? Or do you want $var is not x AND not y? — Etan Reisner
– Etan Reisner, Commented Feb 4, 2015 at 22:56
can you talking to me about the difference because now I am a bit confused about what I want it to do.....sorry — Crisly Domingos
– Crisly Domingos, Commented Feb 4, 2015 at 23:03

osirisgothra · Accepted Answer · 2015-02-05 00:02:05Z

1

you can just:

while [[ $(read -sn1 character; echo ${character^^})  =~ [^YN] ]]; do
  echo -n "Wrong key ..."
done

you'll want -s unless you want the key echoed
you will want to have -n1 to limit the input to ONE character
you can also check for ctrl+c and ctrl+d pressed via $? (ctrl-d is 1 and ctrl+c is 130, but ctrl+d catching only works if you include the -e flag and use readline)
you can include a prompt in there too if you want, and also, you dont have to use '$character' you can just give it nothing and check $REPLY
if you really dont want ctrl+c pressed at all consider using a trap

answered Feb 5, 2015 at 0:02

osirisgothra

2,27225 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Crisly Domingos · Accepted Answer · 2015-02-05 01:07:23Z

1

Thanks a lot to all of you... after a good persistence and resilience I finally found the answer of what I was looking for... A posted the code below:

#if the user's input is not Y or N
while [[ $(read -sn1; echo ${character^^})  =~ [^YN] ]];
do
    echo -n "Re-enter 'y' to exit or 'n'to continue: ?"
    read character
done

answered Feb 5, 2015 at 1:07

Crisly Domingos

751 silver badge9 bronze badges

Comments

code · Accepted Answer · 2015-05-27 09:13:45Z

0

This approach tries to account for more user possibilities and still accomplish the same thing.

#if the user's input is not Y or N, Yes or No, y or n, yes or no
while [[ ! "$character" =~ ^([yY][eE][sS]|[yY])$ ]] && [[ ! "$character" =~ ^([nN][oO]|[nN])$ ]]
do
    echo -n "Wrong key re-enter 'y' to exit or 'n' to continue"
    read character
done

edited May 27, 2015 at 9:13

answered May 27, 2015 at 9:06

code

4,2314 gold badges31 silver badges48 bronze badges

Collectives™ on Stack Overflow

checking two conditions using while loop in bash script

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related