how to run a non-ROS software in ubuntu after i downloaded from github ?

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The software you refer to doesn't seem like a ROS package. So you can just follow the package's instruction to (build if necessary and) run it.

If you're asking how to run the software as a ROS package, I can think of some levels of tasks depending on what part of ROS you want to utilize:

• a. You just want to build the software via ROS' build system (catkin). Then "catkin-ize" it (making software with catkin-compatible). There's actually no document AFAIK that specifically talks about this task, but you may start from catkin's tutorial. Typically this task requires adding package.xml and modifying CMakeLists.txt at minimum.

• b. You want to utilize ROS commandline to access your package or executables in your package (example commands are below). To this you don't need extra tasks except for a.

  roscd your_pkg 
  rosrun your_pkg your_exec
  

• c. If you want to run executables as ROS nodes, you need to change codes in addition to what was necessary in a and b. Again I don't think there are any documents that teach you how to turn non-ROS programs to ROS nodes, so I can only suggest you to go through some of existing tutorials (maybe this, this) to get ideas.