在buildforge中如何获取Linux shell运行的return code

例子：
perl test.pl -option
chmod 777 some_file
ln some_file current_link
以以上三个命令作为例子，如果这三个命令不加任何处理写在build forge的step中，build forge总是以最后一跳命令的返回值最为最后的返回值。
由于buildforge的servr可能安装不同的bash，以hash/ksh为例：


有两种方法来获取return code
1Add multiple dollar signs($) to a variable so to get past the various preparsers.  We have found that in most cases it takes four(4) $$$$?.

perl test.pl -option
if [ 0 -eq $$$$? ] ; then
 echo "(I)script.pl was successful"
else
 echo "(E)test.pl failed"
exit 2
fi

chmod 777 some_file
if [ 0 -eq $$$$? ] ; then
 echo "(I)chmod was successful"
else
 echo "(E)chmod failed"
exit 2
fi

ln some_file current_link
# Since this is the last command you would not have to check the return code as BuildForge will, but we will anyway
if [ 0 -eq $$$$? ] ; then
 echo "(I)Link was successful"
else
 echo "(E)Link failed"
exit 2
fi


2Set the _NO_PREPARSE_COMMAND variable to 1 for a project or a step
关于：
_NO_PREPARSE_COMMAND
    

The system normally attempts to resolve the values of environment variables before sending commands to agents. When the _NO_PREPARSE_COMMAND variable is defined (with any value), the system sends variables to agents without resolving them. Use this variable to ensure that your operating system shell handles the variables.

例子：
.tset env "_NO_PREPARSE_COMMAND=1"
perl test.pl -option
if [ 0 -eq $? ] ; then
 echo "(I)test.pl was successful"
else
 echo "(E)test.pl failed"
exit 2
fi

chmod 777 some_file
if [ 0 -eq $? ] ; then
 echo "(I)chmod was successful"
else
 echo "(E)chmod failed"
exit 2
fi

ln some_file current_link
# Since this is the last command you would not have to check the return code as BuildForge will, but we will anyway
if [ 0 -eq $? ] ; then
 echo "(I)Link was successful"
else
 echo "(E)Link failed"
exit 2
fi


补充一些相关的知识：
http://publib.boulder.ibm.com/infocenter/bldforge/v7r1m2/index.jsp?topic=/com.ibm.rational.buildforge.doc/topics/env_var_interpretation.html

首先：如何在step中定义变量
支持unix风格和windows风格的变量语法
windows风格的如：
set a=100
echo %a%
unix或者linux风格的如：
f=200
echo $f


.tset命令：用来临时改变设置，仅仅在当前步骤中生效。语法.tset env  "<VariableName>=<DesiredValue>" [...]

However, threading can affect this behavior. Example:

   1. A step is threaded and it specifies an Inline.
   2. The first step of the Inline is also threaded.

注意以上两句，不过我还没来及研究

.bset：范围更大，对当前job有效
.bset env "VAR1=VALUE1"
.bset env "VAR2=$VAR1"
如果对一个变量有多个.bset，总是以最后一个运行的有效