Translating this `ip` command to `route` command in `post-up` hook

Question

I am having trouble getting a static routing ip command to become permanent by way of the post-up hook in /etc/network/interfaces. Here are the relevant details:

/etc/network/interfaces

# The loopback network interface
auto lo
iface lo inet loopback

# Network A
allow-hotplug eth0
iface eth0 inet static
address 10.1.10.100
netmask 255.255.255.0
gateway 10.1.10.1

# Network B
allow-hotplug eth1
iface eth1 inet static
address 192.168.100.1
netmask 255.255.0.0
gateway 127.0.0.1

The relevant ip command and routing table

ip route add 192.168.50.0/24 via 10.1.10.100 dev eth0
# This command makes things happy...

$ ip route show
default via 10.40.16.1 dev eth0
10.1.10.0/24 dev eth0  proto kernel  scope link  src 10.1.10.100
192.168.0.0/16 dev eth1  proto kernel  scope link  src 192.168.100.1
192.168.50.0/24 via 10.1.10.100 dev eth0

The (not working) post-up / post-down hooks

#/etc/network/interfaces

# Network A
allow-hotplug eth0
iface eth0 inet static
address 10.1.10.100
netmask 255.255.255.0
gateway 10.1.10.1
post-up route add -net 192.168.50.0 netmask 255.255.255.0 eth0
post-down route del -net 192.168.50.0 netmask 255.255.255.0 eth0

# Network B
allow-hotplug eth1
iface eth1 inet static
address 192.168.100.1
netmask 255.255.0.0
gateway 127.0.0.1

Disclaimers

The ip route add... command does the trick, but I need this to be a permanent static route so hence the post-up stuff. I just can't seem to get the syntax right. When I run try the version of the /etc/network/interfaces on a local test network the route does not show up in the routing table after a reboot, so I think it is failing to run the post-up hook due to bad syntax.

Update

The manage for /etc/network/interfaces isn't much help on giving me a clue on the syntax for the post-up commands either here is all I found:

post-up

Run command after bringing the interface up. If this command fails then ifup aborts, refraining from marking the interface as configured (even though it has really been configured), prints an error message, and exits with status 0. This behavior may change in the future.

Answer 1

Simply add the ip command as an up command in /etc/network/interfaces (no need to translate to route, post-up is an alias for up):

allow-hotplug eth0
iface eth0 inet static
   address 10.1.10.100
   netmask 255.255.255.0
   gateway 10.1.10.1
   up ip route add 192.168.50.0/24 via 10.1.10.100 dev eth0

No need for a down, as when the interface goes down, any routes via that interface will be removed automatically.

Aside: you're adding a route to another network via the local IP address that was just brought up? Is this system being used as a gateway?

EDIT:

The up, down, pre-up etc. labels are just that: labels to indicate what commands need to be run at that time. Those commands can be anything, e.g. send an email or whatever. No special syntax...