Este deve fazer o que você espera
#!/usr/bin/env bash
if [ $# -eq 0 ]; then
echo "No arguments supplied";
else # at least the process name was passed ()
num=$(pgrep -c -x "");
if [ "$num" -gt 1 ]; then # more than one process found
pidof ""
elif [ "$num" -lt 1 ]; then
echo "Warning: the program doesn't have any processes";
else
signal=SIGINT # default signal
if [ $# -ge 2 ]; then # signal provided, use it
signal=
fi
pr=$(pidof "")
kill -"$signal" "$pr"
fi
fi