ROS launch setup problem

I have this Error How to fix it ?
when ı wrote this ı got this error
input :
roslaunch mavros apm.launch.
[apm.launch.] is neither a launch file in package [mavros] nor is [mavros] a launch file name
The traceback for the exception was written to the log file

Hi @EmreEngin,

The correct command is roslaunch mavros apm.launch

Without dot in the end.

We will fix this typo in our docs soon. Thanks!