shell 嵌套条件语句时，尽量把靠近两次判断

if [ $# != 2 ]

then

if [ $1 = "h" -o $1 = "H" ]

then

echo "help info"

else

echo "ERROR: Invalid argument amount! Plz input 2 directory names!"

fi

echo "**************************************************************"

echo "* by Richard Zhang, Oct, 2008. *"

echo "* China Contruction Bank, SuZhou Branch *"

echo "* Usage example: 'sh $0 <dir1> <dir2>' *"

echo "* for help: 'sh $0 h' *"

echo "**************************************************************"

exit 0

fi

没有问题，但是，如果

if [ $# != 2 ]

then

echo "**************************************************************"

echo "* by Richard Zhang, Oct, 2008. *"

echo "* China Contruction Bank, SuZhou Branch *"

echo "* Usage example: 'sh $0 <dir1> <dir2>' *"

echo "* for help: 'sh $0 h' *"

echo "**************************************************************"

if [ $1 = "h" -o $1 = "H" ]

then

echo "help info"

else

echo "ERROR: Invalid argument amount! Plz input 2 directory names!"

fi

exit 0

fi

则在FreeBSD6.1下运行时，提示“[: =: unexpected operator”

真实奇怪。