[gazebo_ros] Fix invalid signal name on OS X for script/gazebo

[bgromov]

Fixes the following error on OS X

scripts/gazebo: line 30: kill: SIGINT: invalid signal specification

by feeding system-dependent argument to kill command. On OS X it is kill -s INT instead of kill -s SIGINT.

[scpeters]

+1

[scpeters]

Thanks! I cherry-picked to indigo-devel in 03a1e27

[dirk-thomas]

For me on Xenial I do have the same problem. When running the gazeboscript it fails to kill gzserver at the end with the following error message:

kill: invalid signal number or name: SIGINT

When changing the signal name to INT (as this PR does for OS X) it works for me on Xenial.

Another reference mentioning this: http://stackoverflow.com/questions/16423732/linux-shell-kill-signal-sigkill-kill

[dirk-thomas]

@nkoenig just mentioned to me that the problem will be addressed by #472 (and a new patch release of Gazebo 7).

[scpeters]

I'm not sure if #472 will help, since it wouldn't work with the upstream Ubuntu gazebo 7.0.0

what if we just switch to kill -n 2 instead of trying to name the signal?