Check for invalid input in a menu - bash

Question

I am making a script where the user selects a number 1-5 and it will loop until the user enters 5. I don't want to use the exit command. I wanted to check to make sure the user doesn't enter anything but 1-5 and if they do display invalid input.
any help would be appreciated
#!/bin/bash
PS3='Please enter your choice: '
options=("1.Move empty files" "2.Check file size" "3.Which files is newer" "4.File check rwx" select opt in "${options[#]}")
while($opt != 5); do
case $opt in
"Option 1")
echo "you chose choice 1"
;;
"Option 2")
echo "you chose choice 2"
;;
"Option 3")
echo "you chose choice 3"
;;
"Option 4")
echo "you chose choice 3"
;;
"Option 5")
break
;;
) echo invalid input;;

Answer 1

You seem confused. I don't even know where to begin correcting whatever misconceptions you have about how this works
In your original code the way you set options is unlikely to do anything useful.
options=("1.Move empty files" "2.Check file size" "3.Which files is newer" "4.File check rwx" select opt in "${options[#]}"
printf '%s\n' "${options[#]}"
This will emit
1.Move empty files
2.Check file size
3.Which files is newer
4.File check rwx
select
opt
in
The select command will not have been executed.
Here's something that does what you seem to want.
options=(
'Move empty files'
'Check file size'
'Which file is newer'
'File check rwx'
)
PS3='Please enter your choice: '
select opt in "${options[#]}" ; do
[[ -n $opt ]] && break || {
echo "invalid input"
}
done
echo "user chose '$opt'"
You could go with a while and case solution and get nearly the same results e.g.:
options=(
'Move empty files'
'Check file size'
'Which file is newer'
'File check rwx'
)
for (( i=0 ; i < ${#options[#]} ; i++ )) ; do
printf '%d) %s\n' $((i+1)) "${options[$i]}"
done
while true ; do
read -p 'Please enter your choice: ' opt
case "$opt" in
[1-5])
opt="${options[$opt]}"
break
;;
*)
echo "invalid input"
;;
esac
done
echo "user chose '$opt'"
But you don't need both and, as you can see, using select is much simpler.