Bash script: Trouble with multiple questions/inputs - bash

Question

First post. Thanks in advance for all of your help.
This is a basic script I am trying to write which will change a CentOS system's DNS settings (/etc/resolv.conf). The script should do the following:
Get DNS1
Ask if there is another DNS
If yes, move to #3 (get DNS2)
If no, write '/etc/resolv.conf' with only a single DNS entry.
Get DNS2
Ask if there is another DNS
If yes, move to #5 (get DNS3)
If no, write '/etc/resolv.conf' with only two DNS entries.
Get DNS3
echo DNS1 DNS2 DNS3, and ask if they are correct
If yes, write '/etc/resolv.conf' with all three DNS entries.
If no, start over. (this part isn't written yet)
This script properly get's DNS1, asks if there is another DNS. If no, it properly writes the file. If no, it moves on to ask for DNS2.
Here is where it no longer works. After it reads DNS2, it does not continue on with the script to prompt if there is an additional DNS. It just freezes. Please let me know if you can see the fault in this process.
#
#!/bin/bash
# FUNCTION TO GRAB THE FIRST DNS
oneDNS()
{
read -p "Enter DNS: (looks like 123.231.132.1) " firstDNS
}
# FUNCTION TO GRAB THE SECOND DNS
twoDNS()
{
read -p "Enter second DNS: (looks like 123.231.132.2) " secondDNS
}
# FUNCTION TO GRAB THE THIRD DNS
threeDNS()
{
read -p "Enter third DNS: (looks like 123.321.132.3) " thirdDNS
}
# FUNCTION WHICH WRITE /etc/resolv.conf IF ONLY
writeOneResolveFile()
{
cat << EOF > $1
nameserver $firstDNS
EOF
#don't use any space before of after 'EOF' in the previous line
echo ""
echo "Your informatons was saved in '$1' file."
echo ""
exit 0
}
writeTwoResolveFile()
{
cat << EOF > $1
nameserver $firstDNS
nameserver $secondDNS
EOF
#don't use any space before of after 'EOF' in the previous line
echo ""
echo "Your informatons was saved in '$1' file."
echo ""
exit 0
}
writeThreeResolveFile()
{
cat << EOF > $1
nameserver $firstDNS
nameserver $secondDNS
nameserver $thirdDNS
EOF
#don't use any space before of after 'EOF' in the previous line
echo ""
echo "Your information was saved in '$1' file."
echo ""
exit 0
}
file="/etc/resolv.conf"
if [ ! -f $file ]; then
echo ""
echo "The file '$file' doesn't exist!"
echo ""
exit 1
fi
clear
echo "Let's set up the DNS your server"
echo ""
oneDNS
echo ""
echo "So DNS settings are:"
echo "DNS Address is: $firstDNS"
echo "Do you have another DNS? [y/n]: "
while true; do
read yn
case $yn in
[Yy]* ) twoDNS;;
[Nn]* ) writeOneResolveFile $file;;
* ) echo "Please enter y or n!";;
esac
done
echo ""
echo "So DNS settings are:"
echo "First DNS Address is: $firstDNS"
echo "Second DNS Address is: $secondDNS"
echo "Do you have another DNS? [y/n]: "
while true; do
read yn
case $yn in
[Yy]* ) threeDNS;;
[Nn]* ) writeTwoResolveFile $file;;
* ) echo "Please enter y or n!";;
esac
done
echo ""
echo "So DNS settings are:"
echo "First DNS Address is: $firstDNS"
echo "Second DNS Address is: $secondDNS"
echo "Third DNS Address is: $thirdDNS"
echo "Is this information correct? [y/n]: "
while true; do
read yn
case $yn in
[Yy]* ) writeThreeResolveFile $file;;
[Nn]* ) ;;
* ) echo "Please enter y or n!";;
esac
done
#
Again, any help is greatly appreciated.
Thanks.
Kamran

Answer 1

check your quotation marks carefully, you're missing one at the end of line 93.

Answer 2

The problem is that after asking for "oneDNS" you enter a endless loop in which you ask for "twoDNS". From this loop you never escape.
Try it out for yourself:
You might want to change your first line to #!/bin/bash -x for debug mode.
echo ""
oneDNS
echo ""
echo "So DNS settings are:"
echo "DNS Address is: $firstDNS"
echo "Do you have another DNS? [y/n]: "
while true; do #<-- how are you planning to escape from this ??
read yn
case $yn in
[Yy]* ) twoDNS;; #<-- this will be asked over and over again
[Nn]* ) writeOneResolveFile $file;;
* ) echo "Please enter y or n!";;
esac
done

Answer 3

Your loops have while true and nothing to break out of the endless loop. You need to specify an exit condition. The way things are, it's just asking for the yn prompt again (the second and subsequent times without any prompt).
A better design might be something like
servers=
another=true
while $another; do
read -p "DNS server address to add?" server
servers="$servers $server"
case $dns in
'') ;;
*) while true; do
read -p "Add another [yn]?" yn
case $yn in [Yy]*) break;; [Nn]*) another=false; break;; esac
done ;;
esac
done
for s in $servers; do
echo nameserver $s
done >/etc/resolv.conf
(Untested, but should hopefully at least suggest some changes.)