求解释如下脚本

################ check CDSDIR environment variable

if (${?CDSDIR}) then

# checks, if CDS-tree exists at specified location

if ( (！ -e ${CDSDIR}/tools/dfII/bin)) then

echo -n "${AMS_ERROR} Fatal Error: "

echo "CDSDIR is set to $CDSDIR, which is not a valid CDS software tree."

exit 1

endif

else

echo -n "${AMS_ERROR} Error: "

echo "Environment variable CDSDIR is not set\！"

echo -n "${AMS_ERROR} Info: "

echo "Please set CDSDIR to the location of the CDS software tree."

exit 1

endif

‘?’什么意思?

在我看来 两端if 无论如何都会报错。

求解释

if (${?CDSDIR}) then==>如果定义了CDSDIR变量，就执行后面的语句