提示用户从目录列表中选择

Question

I am writing a script that will download a dataset from a server onto the local host. I want to prompt the user to select the dataset from a list of ones available on the server. So far I have tried the following command

select DATASET in $(ssh -i ssh_key user@server "ls -1 /path/to/datasets/"); do break; done
1) dataset01
2) test1
3) test2
#?

This produces the list of available datasets as I wanted and puts the dataset filename into the DATASET directory if the user selects a value that is displayed.

However this does not do any validation on the selected entry. If a user enters a value that is not in the list, the select statement I wrote will gladly accept it and move forward.

How can I adapt this command to check if the selected value is within the range of options presented?

Answer 1

You can break only if dataset is not empty, like

PS3="Enter number or 0 for exit> "    #better prompt for the select
values=($(seq -f "set%g" 20))  #simulating 20 datasets 
select dataset in "${values[@]}"
do
    [[ "$dataset" ]] && break  #existing dataset selected, break
    (( "${REPLY}" == 0 )) && exit #0 - exit the script
done
echo =$dataset=

Answer 2

Just wrap your select into

DATASET=
while [[ ! $DATASET ]] ; do
    select DATASET in ...
done

man bash says:

If the line consists of the number corresponding to one of the displayed words, then NAME is set to that word.