有没有一个标准方法可以在空的情况下有条件地添加到env变量中?`

我正在创建一个脚本来配置和启动软件。我当前的应用程序需要附加到ld_library_path。我知道我可以先测试它是否是空的,然后直接设置它,否则附加它。

以下内容似乎不起作用,它会一直附加到变量,即使它包含我在case语句中测试的字符串。

米塞普什

export AXIS2C_HOME=/home/ojblass/Source/axis2c-src-1.6.0
if [ "$LD_LIBRARY_PATH" == "" ]; then
   echo empty setting
   export LD_LIBRARY_PATH=${AXIS2C_HOME}/lib
else
   case $LD_LIB_PATH in
   *$AXIS2C_HOME/lib* )
       echo already there skipping;;
   * )
       echo has entries but appending
       export LD_LIBRARY_PATH=${AXIS2C_HOME}/lib:${LD_LIBRARY_PATH};;
   esac
fi
echo AXIS2C_HOME=${AXIS2C_HOME}
echo LD_LIBRARY_PATH=${LD_LIBRARY_PATH}

示例运行

ojblass@helium:~/Source/axis2c-src-1.6.0$ pwd
/home/ojblass/Source/axis2c-src-1.6.0
ojblass@helium:~/Source/axis2c-src-1.6.0$ . ./mysetup.sh
empty setting
AXIS2C_HOME=/home/ojblass/Source/axis2c-src-1.6.0
LD_LIBRARY_PATH=/home/ojblass/Source/axis2c-src-1.6.0/lib
ojblass@helium:~/Source/axis2c-src-1.6.0$ . ./mysetup.sh
has entries but appending
AXIS2C_HOME=/home/ojblass/Source/axis2c-src-1.6.0
LD_LIBRARY_PATH=/home/ojblass/Source/axis2c-src-1.6.0/lib:/home/ojblass/Source/axis2c-src-1.6.0/lib

正如您注意到的,ld_库\路径不断被添加到。另外,我有点担心自己是特定于外壳的,不能像我想的那样方便携带。感谢您的任何建议。