bash interactive menu, exit on empty input - bash

Question

I have tried to piece together a script to list different jws directories and allow user to select different client directories before it continues on to edit jnlp files within the directory. I have the edit part working, I have the menu working mostly; I can't figure out how to exit the loop once the selections have been made.
I'd like it to exit once ENTER is hit without a number selection, and continue with the next part of the script.
function update_jnlp
{
while :
do
# JNLP update submenu
options=($(ls /tmp/test/ | grep "jws$"))
menu() {
clear
echo "Locally installed jnlps:"
for i in ${!options[#]}; do
printf "%3d%s) %s\n" $((i+1)) "${choices[i]:- }" "${options[i]}"
done
[[ "$msg" ]] && echo "$msg"; :
}
prompt="Check an option (again to uncheck, ENTER when done): "
while menu && read -rp "$prompt" num && [[ "$num" ]]; do
[[ "$num" != *[![:digit:]]* ]] &&
(( num > 0 && num <= ${#options[#]} )) ||
{ msg="Invalid option: $num"; continue; }
((num--)); msg="${options[num]} was ${choices[num]:+un}checked"
[[ "${choices[num]}" ]] && choices[num]="" || choices[num]="+"
done
printf "You selected"; msg=" nothing"
for i in ${!options[#]}; do
[[ "${choices[i]}" ]] && { printf " %s" "${options[i]}"; msg=""; }
done
done
for i in ${choices[#]}; do
printf "%s\n" ${choices[#]};
echo "fun"
done
echo "#msg"
# here is the script to edit the files now contained as ${choices[#]}
}
I recognize that I am in a menu loop and that I need to validate that input from the read command = "" or that $prompt input is null, and I assume I break from there

Answer 1

Please format your code more readably. As it stands, the erratic indentation makes it close to unreadable. Well, the indentation combined with defining a function in the body of a loop inside another function, and some of the more inscrutable loop bodies I've ever seen. (I thought I'd seen quite a lot; clearly, I've still got some learning to do.)
With the code formatted somewhat more orthodoxly, you have:
function update_jnlp
{
while :
do
# JNLP update submenu
options=($(ls /tmp/test/ | grep "jws$"))
menu() {
clear
echo "Locally installed jnlps:"
for i in ${!options[#]}; do
printf "%3d%s) %s\n" $((i+1)) "${choices[i]:- }" "${options[i]}"
done
[[ "$msg" ]] && echo "$msg"; :
}
prompt="Check an option (again to uncheck, ENTER when done): "
while menu && read -rp "$prompt" num && [[ "$num" ]]; do
[[ "$num" != *[![:digit:]]* ]] &&
(( num > 0 && num <= ${#options[#]} )) ||
{ msg="Invalid option: $num"; continue; }
((num--)); msg="${options[num]} was ${choices[num]:+un}checked"
[[ "${choices[num]}" ]] && choices[num]="" || choices[num]="+"
done
printf "You selected"; msg=" nothing"
for i in ${!options[#]}; do
[[ "${choices[i]}" ]] && { printf " %s" "${options[i]}"; msg=""; }
done
echo "$msg" # Added
break # Added
done
for i in ${choices[#]}; do
printf "%s\n" ${choices[#]};
echo "fun"
done
echo "#msg"
# here is the script to edit the files now contained as ${choices[#]}
}
When I ran it, I selected 1, 3, 7 and then hit return, and the final page of output looked like:
Locally installed jnlps:
1+) abc.jws
2 ) def.jws
3+) ghi.jws
4 ) jkl.jws
5 ) mno.jws
6 ) pqr.jws
7+) stu.jws
8 ) vwx.jws
9 ) xyz.jws
stu.jws was checked
Check an option (again to uncheck, ENTER when done):
You selected abc.jws ghi.jws stu.jws
+
+
+
fun
+
+
+
fun
+
+
+
fun
#msg
Without the added break, you don't get to see what's selected because the outer while : loop clears the screen too quickly. With the echo "$msg" added, you get You selected nothing as you'd want.
The material after the main while : loop is clearly not finalized.
In fact, you don't need the while : loop at all, or the incomplete material. You could use:
function update_jnlp
{
# JNLP update submenu
options=($(ls /tmp/test/ | grep "jws$"))
menu() {
clear
echo "Locally installed jnlps:"
for i in ${!options[#]}; do
printf "%3d%s) %s\n" $((i+1)) "${choices[i]:- }" "${options[i]}"
done
[[ "$msg" ]] && echo "$msg"; :
}
prompt="Check an option (again to uncheck, ENTER when done): "
while menu && read -rp "$prompt" num && [[ -n "$num" ]]; do
[[ "$num" != *[![:digit:]]* ]] &&
(( num > 0 && num <= ${#options[#]} )) ||
{ msg="Invalid option: $num"; continue; }
((num--)); msg="${options[num]} was ${choices[num]:+un}checked"
[[ "${choices[num]}" ]] && choices[num]="" || choices[num]="+"
done
printf "You selected"; msg=" nothing"
for i in ${!options[#]}; do
[[ "${choices[i]}" ]] && { printf " %s" "${options[i]}"; msg=""; }
done
echo "$msg"
}
That's still rather inscrutable, but at least it works more or less sanely.