ROS中的环境变量
参考http://wiki.ros.org/ROS/EnvironmentVariables
Master:节点管理器，ROS名称服务 (比如帮助节点找到彼此)。
rosout: ROS中相当于stdout/stderr。
roscore: 主机+ rosout + 参数服务器 (参数服务器会在后面介绍)。
查看环境变量
robot@ubuntu:~$ env | grep ROS
ROS_ROOT=/opt/ros/indigo/share/ros
ROS_PACKAGE_PATH=/opt/ros/indigo/share:/opt/ros/indigo/stacks
ROS_MASTER_URI=http://localhost:11311
ROSLISP_PACKAGE_DIRECTORIES=
ROS_DISTRO=indigo
ROS_ETC_DIR=/opt/ros/indigo/etc/ros
环境变量的作用：
CmakeList.txt 中的finding packages（）里面需要列出所需要依赖的ros包
ROS能找到他们，需要依赖ROS_ROOT 和 ROS_PACKAGE_PATH
ROS_ROOT 指向了ROS的core package
ROS_PACKAGE_PATH指向了ros包的位置。
安装ROS把source /opt/ros/indigo/setup.bash 保证了该环境变量的生成！！
影响结点运行
ROS_MASTER_URI 告诉结点Master在哪里，提供名称服务，互相找到彼此。甚至分布式计算在不同计算机之间的通信。
ROS_MASTER_URI is a required setting that tells nodes where they can locate the master. It should be set to the XML-RPC URI of the master. Great care should be taken when using localhost, as that can lead to unintended behaviors with remotely launched nodes.
export ROS_MASTER_URI=http://mia:11311/
ROS_IP和 ROS_HOSTNAME影响结点的网络地址
ROS_NAMESPACE允许你改变命名空间
ROS_LOG_DIR 允许你改变目录文件保存的目录，默认为~/.ros/log
修改编译系统：
ROS_BINDEPS_PATH, ROS_BOOST_ROOT, ROS_PARALLEL_JOBS, ROS_LANG_DISABLE 影响了怎么查找库文件，怎么编译等
PYTHONPATH
robot@ubuntu:~$ env | grep PY
PYTHONPATH=/opt/ros/indigo/lib/python2.7/dist-packages
export PYTHONPATH=$PYTHONPATH:$ROS_ROOT/core/roslib/src
ROS_PACKAGE_PATH
export ROS_PACKAGE_PATH=/home/user/ros/ros-pkg:/another/path
#将自己的catkin_workspace增加入环境变量。这样roscd roslist 才能找到用户创建的包。
ROS_HOME
一般值~/.ROS
robot@ubuntu:~/.ros$ ls
log rospack_cache_00838615507935911151
roscore-11311.pid rospack_cache_11486458967921186402
rosdep rosstack_cache_11486458967921186402
ROS_LOG_DIR
一般指ROS_HOME/log/
可改
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节点的环境变量
ROS_IP/ROS_HOSTNAME
ROS_NAMESPACE
将一个节点放入一个命名空间。
典型的例子是turtlebot 两个小海龟，后一个海归跟随第一个海归的实例。launch中
printenv | grep CM*
CMAKE_PREFIX_PATH=/opt/ros/indigo
locate rosrun
/opt/ros/indigo/bin/rosrun
rosrun只不过是一个shell脚本，能够理解ROS的文件组织结构，当然结点之间能够互相找到，是结点管理器提供的名称注册/名称查找的作用。
而rosrun能够像linux系统命令可以执行的原因是：
echo $PATH
/opt/ros/indigo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
结点名和可执行文件名字不一定一样
1.节点名在程序内部实例化结点由一段字符串命名
1 // This is a ROS version of the standard "hello , world"
2 // program.
3
4 // This header defines the standard ROS classes .
5 #include
6
7 int main ( int argc , char ** argv ) {
8 // Initialize the ROS system .
9 ros::init ( argc , argv , " hello _ros " ) ;//"hello_ros"为结点名
10
11 // Establ ish this program as a ROS node .
12 ros::NodeHandle nh ;
13
14 // Send some output as a log message .
15 ROS_INFO_STREAM( " Hello , ␣ ROS! " ) ;
16 } 2.命令行重映射 rosrun package-name executable-name __name:=new_node_name
3.launch文件，ns="" pkg="" type="executable-file-name" name="new_node_name"
4. rosnode info/rosnode cleanup
rosout
rosout本身就是一个结点，随roscore启动（还有参数管理器，结点管理器）,类似std::cout 到屏幕的标准输出。椭圆表示结点，方框表示话题
产生一个话题/rosout
ROS_INFO()
ROS_WARN()
ROS_FAULT()
rostopic info topic-name /rostopic echo topic-name /rosmsg type msg-name
rostopic pub –r 1 /turtle1/cmd_vel geometry_msgs/Twist ’[2,0,0]’ ’[0,0,0]’ ##该消息有两个域，两个‘【】’代表两个域
自动在命令行输出特定消息格式的方式输出话题名 数据类型名 后，tab（自动补全消息的所有域及其顺序）
rostopic pub /turtle1/cmd_vel geometry_msgs/Twist "linear:
x: 0.0
y: 0.0
z: 0.0
angular:
x: 0.0
y: 0.0
z: 0.0"
编译：
当第一次在~/catkin_ws/编译时，使用catkin_make
以后添加功能包时，可以使用catkin_make --force-cmake
catkin_make -pkg your-new-pkg-name
Using CATKIN_DEVEL_PREFIX: /home/robot/danimtb_ws/devel
-- Using CMAKE_PREFIX_PATH: /opt/ros/indigo
-- This workspace overlays: /opt/ros/indigo
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /home/robot/danimtb_ws/build/test_results
-- Found gtest sources under '/usr/src/gtest': gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.6.19
-- BUILD_SHARED_LIBS is on
-- Configuring done
-- Generating done
-- Build files have been written to: /home/robot/danimtb_ws/build
关于肖军浩《机器人操作系统浅析》第61页，有一处错误，编译后build空间可以删除（正确），但是devel空间不可以删除，生成的结点在devel/lib/agitr/hello
robot@ubuntu:~/danimtb_ws$ catkin_make
Base path: /home/robot/danimtb_ws
Source space: /home/robot/danimtb_ws/src
Build space: /home/robot/danimtb_ws/build
Devel space: /home/robot/danimtb_ws/devel
Install space: /home/robot/danimtb_ws/install
####
#### Running command: "cmake /home/robot/danimtb_ws/src -DCATKIN_DEVEL_PREFIX=/home/robot/danimtb_ws/devel -DCMAKE_INSTALL_PREFIX=/home/robot/danimtb_ws/install -G Unix Makefiles" in "/home/robot/danimtb_ws/build"
####
-- The C compiler identification is GNU 4.8.4
-- The CXX compiler identification is GNU 4.8.4
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Using CATKIN_DEVEL_PREFIX: /home/robot/danimtb_ws/devel
-- Using CMAKE_PREFIX_PATH: /home/robot/danimtb_ws/devel;/opt/ros/indigo
-- This workspace overlays: /home/robot/danimtb_ws/devel;/opt/ros/indigo
-- Found PythonInterp: /usr/bin/python (found version "2.7.6")
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /home/robot/danimtb_ws/build/test_results
-- Looking for include file pthread.h
-- Looking for include file pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Found gtest sources under '/usr/src/gtest': gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.6.19
-- BUILD_SHARED_LIBS is on
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~ traversing 1 packages in topological order:
-- ~~ - agitr
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- +++ processing catkin package: 'agitr'
-- ==> add_subdirectory(agitr)
-- Configuring done
-- Generating done
-- Build files have been written to: /home/robot/danimtb_ws/build
####
#### Running command: "make -j1 -l1" in "/home/robot/danimtb_ws/build"
####
Scanning dependencies of target hello
[100%] Building CXX object agitr/CMakeFiles/hello.dir/hello.cpp.o
Linking CXX executable /home/robot/danimtb_ws/devel/lib/agitr/hello
[100%] Built target hello
使用apt安装软件包之后，ros的更新软件包目录的工具
$ rospack profile #更新一下ROS内部软件包
#rospack profile功能类似于使用sudo apt-get update更新Linux软件包一样。它的功能是：更新ros软件包robot@ubuntu:/usr/include/x86_64-linux-gnu$ echo $CMAKE_PREFIX_PATH
/opt/ros/indigo
robot@ubuntu:/usr/include/x86_64-linux-gnu$ cd ~/catkin_ws/
robot@ubuntu:~/catkin_ws$ . devel/setup.bash
robot@ubuntu:~/catkin_ws$ echo $CMAKE_PREFIX_PATH
/home/robot/catkin_ws/devel:/opt/ros/indigo
详细参见以上网址