How to change bash script output when the script is running? I have the following loop which counts from 0 till 99: #!/bin/bash for ((i=0;i<100;i++)); do echo $i sleep 1 done Is there a way to change the result of the output from terminal while this loop script is running. Lets say if I press letter k the loop automatically add 10 more number to the current number, so if we have 10 being displayed on the screen and we press K the loop should automatically change to 20! Thanks

As mentioned in comment you can use:


read -t 1 -n 1 key


which because of `-t` option we can remove `sleep`, so your script could be:


#!/bin/bash

for ((i=0; i<100; i++)); do
read -t 1 -n 1 key
if [ "$key" = "k" ]; then
i=$((i + 10))
fi
echo $i
done


But I think more portable could be:


#!/bin/bash

if [ -t 0 ]; then stty -echo -icanon -icrnl time 0 min 0; fi

keystroke=''
i=0
while [ $i -lt 100 ]; do
keystroke="$(dd bs=1 count=1 2>/dev/null)" #
if [ "$keystroke" = "k" ]; then
i=$(( i + 10 ))
elif [ "$keystroke" = "q" ]; then
break
fi
i=$(( i + 1 ))
echo $i
sleep 1
done

if [ -t 0 ]; then stty sane; fi

exit 0