how to check if $1 and $2 are null?

Question

I am running some script which passing the string argument and I want to do if else statement shown as below:

if [ $1 != '' ] && [ $2 != '' ]
then 
    do something.....

but it shown Error too many argument. Why?

Answer 1

Try using the -z test:

if [ -z "$1" ] && [ -z "$2" ]

From man bash:

-z string
   True if the length of string is zero.

Answer 2

由于这是标记为bash，我建议使用扩展测试结构 ( [[...]])，并忘记引号：

if [[ -z $1 && -z $2 ]]; then
...

除非您要与sh/POSIX 兼容，否则没有理由不使用[[ ]].

Answer 3

The following also works,

if [ "$1" == "" && "$2" == ""]; then
    echo NULL
fi