HZ's profile - activity

Hi All,

Some of my ROS nodes need to be run as a root user. I can do this by "sudo su" under Ubuntu and "source" setup.bash. My programs seem to be running correctly. An annoying issue is that, when I try to use "tab completion" to complete the package name in the terminal (e.g., rosrun package_name executable_name), I got some warnings as follows:

[rospack] WARNING: cannot create rospack cache directory: Permission denied
[rospack] WARNING: cannot create rospack cache directory: Permission denied
[rospack] Unable to create temporary cache file /root/.ros/.rospack_cache.bGXJPX: Permission denied

I have done this: chmod -R a+rwx /root/.ros/, but above warnings still come out.

Any suggestion for solving this problem is appreciated.

Hi All,

I have two nodes: A and B implemented in C++. Now I want Node A to be launched (by the program, not by users' input in the terminal) within the execution of Node B that is launched by users in the terminal. Is there a ROS way to do this? Or should I just encode a shell command in B's source code to launch A, like executing a shell command in C++ programs?

Thanks,

Hi All,

I want to develop some ROS packages which contain libraries for other packages to use, and have some questions about the development process:

1) Should I use rosmake or rosbuild to compile and build my packages? 2) Which files should I modify to create libraries (.so files) instead of executables?

Thanks, HZ

Hi All,

I encountered a problem while linking a ROS program against some external libraries. I am trying to link my ROS program against Xenomai libraries. To make sure Xenomai libraries have been successfully installed in my OS (Ubuntu 10.10), I built a simple program (non-ROS) with gcc like this:

gcc -I/usr/xenomai/include -D_GNU_SOURCE -D_REENTRANT -D__XENO__ -Wall -pipe -lnative -L/usr/xenomai/lib -lxenomai -lpthread -lrtdk hellworld.c -o helloworld

No problems arise here, and I got the executable.

To build my ROS programs (take as an example the tutorial program at the ROS website ), I add the following commands to CMakeLists.txt:

rosbuild_add_executable(listener src/listener.cpp)
include_directories(/usr/xenomai/include)
add_definitions(-D_GNU_SOURCE -D_REENTRANT -D__XENO__)
rosbuild_add_compile_flags(listener -Wall -pipe)
link_directories(/usr/xenomai/lib)
target_link_libraries(listener native xenomai pthread rtdk)

That says, I want to link the “listener” node against some Xenomai libraries, like “native”, “xenomai”, etc. However, when I rosmake’d the whole package, I got this error:

  Linking CXX executable ../bin/listener
  /usr/bin/ld: cannot find -lnative
  /usr/bin/ld: cannot find -lxenomai
  collect2: ld returned 1 exit status

It seems rosbuild did not search libraries in “/usr/xenomai/lib” which is supposed to specified by link_directories(/usr/xenomai/lib). Did I miss something to tell rosbuild to search libraries in “/usr/xenomai/lib”?

With many thanks,

You could add the ROS_PACKAGE_PATH to the root user's .bashrc. In Ubuntu, this is taboo, but in systems where you act as the root user often, it could be helpful.

The usual ROS way is running them both from a roslaunch script.

From the rosbuild wiki page:

"To build packages, use rosmake."

rosbuild is the name of the library of build-support tools; rosmake is the command you run to actually build stuff. Assuming you're developing your code just for ROS use (as distinct from implementing a ROS wrapper around some library that needn't be / isn't ROS-aware), you should do everything in CMakeLists.txt in your package's root directory. (Everything except setting the exports; that's in manifest.xml).

If you want to compile libraries, use the rosbuild_add_library macro; see the rosbuild wikipage for some examples, and the default CMakeLists.txt that roscreate-pkg gives you.

Hi All,

For some particular reason, I need to step into /opt/ros/electric/stacks/vision_opencv/cv_bridge/src/cv_bridge.cpp for debugging purpose, and I want to examine the value of int source_type in the function of toCvCopy. However, when I print source_type in gdb, it says "value optimized out". So how can I re-compile & build cv_bridge without optimization, so I can examine the value of source_type?

Thanks

After some googling, I found this. I think I can now answer the problem myself: It turned out that I need to place link_directories(/usr/xenomai/lib) before rosbuild_add_executable(listener src/listener.cpp), that is,

link_directories(/usr/xenomai/lib)
rosbuild_add_executable(listener src/listener.cpp)
include_directories(/usr/xenomai/include)
add_definitions(-D_GNU_SOURCE -D_REENTRANT -D__XENO__)
rosbuild_add_compile_flags(listener -Wall -pipe)
target_link_libraries(listener native xenomai pthread rtdk)

Is this a bug, or a restriction of CMake? Is it documented somewhere?