[CentOS] making a route sticky

>>ip route add 192.168.1.0/24 via 1.2.3.4 src 192.168.2.1

> The network scripts are prepared for this. Create a file called
> /etc/sysconfig/network-scripts/route-<devicename> with content
> "192.168.1.0/24 via 1.2.3.4 src 192.168.2.1" (the ip route add is
> executed by the network script automatically). You can read about that
> in /usr/share/doc/initscripts*/sysconfig.txt.

ADDRESS0=192.168.1.0
NETMASK0=255.255.255.0
PREFIX=255.255.255.0
GATEWAY0=1.2.3.4