Why are post-up commands in /etc/network/interfaces ran multiple times at boot?

Here is the content of /etc/network/interfaces: auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp post-up /etc/network/if-up.d/sshstart And sshstart is a script with the following in it: curl something something darkside send a file over ftps in the background & /usr/bin/autossh -M 0 -f -N -o ServerAliveInterval=15 -o ServerAliveCountMax=3 -R 127.0.0.1:2005:127.0.0.1:22 -R 192.168.1.10:2006:192.168.2.110:1912 -L 127.0.0.1:5249:192.168.1.212:5249 username@17.16.15.2 -p 8080 When the machine reboots, the curl command is executed multiple times, the file ends up 2 or 3 times on the ftp server and when I look at the processes it seems like there are multiple instances of autossh running... Not sure if this is how autossh does things or not, but for sure curl shouldn't upload the file multiple times. My hunch is that the whole sshstart script is ran multiple times but I don't understand why. I tried searching for details on the network setup process at boot but all I could find was syntax information for the interfaces file. Can someone help please? Thank you. **---Edit---**

As suggested bellow I have modified my interfaces file as follow (removed the empty lines above post-up): auto lo iface lo inet loopback auto eth0 iface eth0 inet dhcp post-up /etc/network/if-up.d/sshstart And added the following line to sshstart: echo $(date)>>/run/shm/sshstart.log Here is the content of /run/shm/sshstart.log after a reboot: Wed Oct 29 08:07:00 EDT 2014 Wed Oct 29 08:07:07 EDT 2014 Wed Oct 29 08:07:07 EDT 2014 Wed Oct 29 08:07:07 EDT 2014 So its been ran 4 times :( what's going on?