sv-replace

#!/bin/bash
#
#  "sv-replace" script by furryfixer to replace one runit service with another.
#  Invoke in the form "sv-replace <old service> <new service>"
#  Useful for swapping login display managers such as XDM, LXDM, SDDM,
#  or network managers, etc.
#  Stops running service before replacing.
#  Service names must match entries in /etc/sv

if [ "$EUID" -ne 0 ]; then
	echo "You must be ROOT for this command to work"
	exit 1
fi
if [ -z "$2" ] || [ ! -z "$3" ]; then       
        echo "Syntax error. Two and only two operands expected. "\""sv-replace A B"\"
        exit 1
fi
if [ ! -e "/etc/sv/$1" ] || [ ! -e "/etc/sv/$2" ]; then
	echo "Syntax error. Usage is "\""sv-replace A B"\"", where A and B services both exist in /etc/sv"
	exit 1
fi
if [ ! -e "/var/service/$1" ]; then
	echo $1" service not linked in /var/service/. Try "\""sv-add "$2\"" instead."
	exit 1
fi
sv d $1
rm -r /var/service/$1
ln -s /etc/sv/$2 /var/service/
echo "Successfully replaced service "\"$1\"" with "\"$2\" 
exit