Bash: How to end infinite loop with any key pressed?

Question

I need to write an infinite loop that stops when any key is pressed.

Unfortunately this one loops only when a key is pressed.

Ideas please?

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Answer 1

I found this forum post and rewrote era's post into this pretty general use format:

# stuff before main function
printf "INIT\n\n"; sleep 2

INIT(){
  starting="MAIN loop starting"; ending="MAIN loop success"
  runMAIN=1; i=1; echo "0"
}; INIT

# exit script when MAIN is done, if ever (in this case counting out 4 seconds)
exitScript(){
    trap - SIGINT SIGTERM SIGTERM # clear the trap
    kill -- -$$ # Send SIGTERM to child/sub processes
    kill $( jobs -p ) # kill any remaining processes
}; trap exitScript SIGINT SIGTERM # set trap

MAIN(){
  echo "$starting"
  sleep 1

  echo "$i"; let "i++"
  if (($i > 4)); then printf "\nexiting\n"; exitScript; fi

  echo "$ending"; echo
}

# main loop running in subshell due to the '&'' after 'done'
{ while ((runMAIN)); do
  if ! MAIN; then runMain=0; fi
done; } &

# --------------------------------------------------
tput smso
# echo "Press any key to return \c"
tput rmso
oldstty=`stty -g`
stty -icanon -echo min 1 time 0
dd bs=1 count=1 >/dev/null 2>&1
stty "$oldstty"
# --------------------------------------------------

# everything after this point will occur after user inputs any key
printf "\nYou pressed a key!\n\nGoodbye!\n"

Run this script