Bash Wait Command – When and Why It Is Needed

You can do this by using a temporary directory.

# Create a temporary directory to store the statuses
dir=$(mktemp -d)

# Execute the backgrouded code. Create a file that contains the exit status.
# The filename is the PID of this group's subshell.
for i in 1 2; do
    { ssh mysql "/root/test$i.sh" ; echo "$?" > "$dir/$BASHPID" ; } &
done

# Wait for all jobs to complete
wait

# Get return information for each pid
for file in "$dir"/*; do
    printf 'PID %d returned %d\n' "${file##*/}" "$(<"$file")"
done

# Remove the temporary directory
rm -r "$dir"

while true;do echo -n .;sleep 1;done &
sleep 10 # or do something else here
kill $!; trap 'kill $!' SIGTERM
echo done

this will start an infinite while loop that echos a spinner every second, executed in the background.

Instead of the sleep10 command run any command you want.

When that command finishes executing this will kill the last job running in the background (which is the infinite while loop)

source: https://stackoverflow.com/a/16348366/1069083

You can use various while loops instead, e.g. a spinner like this:

while :;do for s in / - \\ \|; do printf "\r$s";sleep 1;done;done