Question about K Shell

[microsky]

Please see following K shell command, in the IF statement, why the result is same when use "-z" and "-n" parameter?

$ set |grep SHELL
SHELL=/bin/ksh
$ set |grep FILE_NAME
FILE_NAME=''
$ if [ -n $FILE_NAME ] ;
> then
> echo "fa"
> fi
fa
$ if [ -z $FILE_NAME ] ;
> then
> echo "fa"
> fi
fa
$

 

[mrmac228]

Think you need some quotes round the $FILE_NAME to ensure that it gets treated as a string.

 

[microsky]

Thank you very much!
I changed as following, it is right.
$if [ -n "$FILE_NAME" ] ;
> then
> echo "fa"
> fi
$