How to pause a loop to allow for user selection of variables

Question

I cannot seem to figure out how to make this loop pause for user selection. It automatically chooses the * selection every time. What am I doing wrong?

#!/bin/bash    

while read -r lineIn; do 
if [[ "$(cmd_output)" != "" ]]; then
   echo "choose one letter (a)(b)(c)(d)(e)" 
   read abcde  
      case $abcde in
         [aA] ) do stuff and continue the loop;;
         [bB] ) do stuff and do not continue the loop;;
         [cC] ) do other stuff and continue the loop
         [dD] ) do nothing and continue the loop;;
         [eE] ) exit;;  
            * ) echo "Danger Will Robinson!";;
      esac
else
   echo "No output from command!"
fi   
done < filename

1. Do you really want/need read -p ? I think just read abcde should work. 2. constructs like [a | A] "boil" down to [aA |], so I think you really just need [Aa] (etc). Otherwise, looks good. Good Luck! — shellter
– shellter, Commented Apr 28, 2016 at 3:11
The reason I added the -p option is because I originally thought it would pause to prompt for user input. But you are right, it is unnecessary. — I0_ol
– I0_ol, Commented Apr 28, 2016 at 3:27
for ksh, the read man page shows that -p is to "Read from the current co-process instead of standard input. An end of file causes read to disconnect the co-process so that another can be created.", but it may be different for bash (too tired to look right now). Good luck. — shellter
– shellter, Commented Apr 28, 2016 at 3:59
It chooses the * every time because there are no break commands at the end of the choices within the loop. — David C. Rankin
– David C. Rankin, Commented Apr 28, 2016 at 14:07
@DavidC.Rankin Having break commands at the end of the choices didn't stop the loop from running unless break was on the * choice. But doing that breaks out of the entire script. And it would automatically run any command found for choice * which could be really bad. Martin's answer has fixed the issue I was having. With read abcde < /dev/tty it waits for one the choices to be entered. But also break is needed now that it works. — I0_ol
– I0_ol, Commented Apr 28, 2016 at 15:26

Martin · Accepted Answer · 2016-04-28 06:58:59Z

2

You need to redirect the "read abcde" to read from the tty.

read abcde < /dev/tty

Because of the while loop the stdin is actually coming from the redirect.

answered Apr 28, 2016 at 6:58

Martin

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