我正在尝试使用需要JSCH 库的SSHEXEC ANT 任务。
当我尝试使用SSHEXEC任务时，我得到以下信息：
BUILD FAILED
/home/www/test/build/build.xml:140: Problem: failed to create task or type sshexec
Cause: the class org.apache.tools.ant.taskdefs.optional.ssh.SSHExec was not found.
This looks like one of Ant's optional components.
Action: Check that the appropriate optional JAR exists in
-/usr/share/ant/lib
-/root/.ant/lib
-a directory added on the command line with the -lib argument
Do not panic, this is a common problem.
The commonest cause is a missing JAR.
This is not a bug; it is a configuration problem
我已将jsch-0.1.50.jar（最新的）放入/usr/share/ant/lib，/root/.ant/lib甚至尝试了以下操作：
ant my-sshexec-target-name -lib /path/to/jsch-0.1.50.jar
而且我不断收到同样的错误。我还尝试将文件重命名为简单地jsch.jar在所有相同的位置。结果相同。我在这里做错了什么？
更新
我也跑了ant -diagnostics，看到了这个：
...
-------------------------------------------
Tasks availability
-------------------------------------------
p4reopen : Not Available (the implementation class is not present)
image : Not Available (the implementation class is not present)
sshexec : Not Available (the implementation class is not present)
wlrun : Not Available (the implementation class is not present)
p4label : Not Available (the implementation class is not present)
p4revert : Not Available (the implementation class is not present)
p4submit : Not Available (the implementation class is not present)
scp : Not Available (the implementation class is not present)
p4change : Not Available (the implementation class is not present)
p4delete : Not Available (the implementation class is not present)
p4integrate : Not Available (the implementation class is not present)
rexec : Not Available (the implementation class is not present)
stlist : Not Available (the implementation class is not present)
telnet : Not Available (the implementation class is not present)
etc...
注意：sshexec ：不可用（实现类不存在）
这意味着什么？