Bash countdown to execution if no key pressed

Question

I've seen this a bunch of times in bash programs. I need to start a timer that can be cancelled on key press. If no key is pressed it will execute a command. Using it for automated vagrant config.

What I want to see in the terminal:

Automatically installing in (10) ## this number should count down
Press any key to cancel automatic install.

Updating the count in-place is the trickiest part of doing this (assuming you don't want to just clear the screen each update). Other than that this is likely just a `read` with a timeout in a loop. — Etan Reisner, Nov 09 '15 at 17:40

score 3 · Accepted Answer · answered Nov 09 '15 at 17:43

3

You can use read for that with time-out option:

read -n 1 -t 10

This will wait 10 seconds for single char. If key was pressed return value will be 0:

if [ $? == 0 ]; then
    # key was pressed
    exit
fi

answered Nov 09 '15 at 17:43

madneon

537
3
17

That worked for me, thanks! – Grant Eagon Nov 09 '15 at 17:56

Bash countdown to execution if no key pressed

1 Answers1