roswtf工具的基本介绍
1 检查你的安装
roswft可以检查你的系统是不是有什么错误：
$ roscd
$ roswtf
你会看到如下信息：
Stack: ros
======================================================
Static checks summary:
No errors or warnings
======================================================
Cannot communicate with master, ignoring graph checks
如果你的安装是正确的，你就会看到类似上面的东西：
-“Stack:ros”：rosetf从你当前的目录来决定你想让它检查什么东西。这一句就是告诉你，它是从ros stack启动的。
-“Static checks summary”：静态检查总结。这是一个文件系统问题报告，它告诉我们这里不存在任何error。
-“Cannot communicate with master, ignoring graph checks”：这个是说肉score没有运行，所以没有进行在线检查。
我的运行出来是这样的：
Loaded plugin tf.tfwtf
No package or stack in context
================================================================================
Static checks summary:
No errors or warnings
================================================================================
ROS Master does not appear to be running.
Online graph checks will not be run.
ROS_MASTER_URI is [http://localhost:11311]
2 尝试在线检查
首先启动ROS:
roscore
打开一个新窗口，重复刚才的步骤：
roscd
roswtf
你会看到类似这样的东西：
Stack: ros
======================================================
Static checks summary:
No errors or warnings
======================================================
Beginning tests of your ROS graph. These may take awhile...
analyzing graph...
... done analyzing graph
running graph rules...
... done running graph rules
Online checks summary:
Found 1 warning(s).
Warnings are things that may be just fine, but are sometimes at fault
WARNING The following node subscriptions are unconnected:
* /rosout:
* /rosout
我的显示的是下面这样的：
Loaded plugin tf.tfwtf
No package or stack in context
================================================================================
Static checks summary:
No errors or warnings
================================================================================
Beginning tests of your ROS graph. These may take awhile...
analyzing graph...
... done analyzing graph
running graph rules...
... done running graph rules
Online checks summary:
Found 1 warning(s).
Warnings are things that may be just fine, but are sometimes at fault
WARNING The following node subscriptions are unconnected:
* /rosout:
* /rosout
roswtf在你rosscore运行的情况下做了一些在线检测，它要运行多长时间才能完成取决于你运行了多少ROS node，它有时候是可以花费很长很长时间的。在这次检查中，它提示了一个warning：
WARNING The following node subscriptions are unconnected:
* /rosout:
* /rosout
这个是提示我们rosout订阅了一个根本没有人发布东西的topic。这是因为现在还没有别的东西在运行，我们可以忽略这个warning。
3 Errors
roswtf会警告你那些看起来可疑但是可能在你的系统里是正常的东西。它还会把它知道是错误的东西通过error报告给你。
这部分，我们会把 ROS_PACKAGE_PATH设置成一个错误的值，我们还要关掉roscore，这样能使检查结果精简一点。
然后输入：
$ roscd
$ ROS_PACKAGE_PATH=bad:$ROS_PACKAGE_PATH roswtf
这次你会看到：
Stack: ros
======================================================
Static checks summary:
Found 1 error(s).
ERROR Not all paths in ROS_PACKAGE_PATH [bad] point to an existing directory:
* bad
======================================================
Cannot communicate with master, ignoring graph checks
这次，roswtf给出了关于 ROS_PACKAGE_PATH 设置的error提示。它还可以检查出许多别的错误，如果你被编译或者通讯的问题困扰住了，可以试一下它能不能指出问题在哪里。
