Tks Mr.miLosh & Mr.Dean, This problem is getting clear now. However, let me please ask one more question that still remains in me. ____________________________________________________________ Mr.miLosh advised; >first of all, in the '-z' example u r giving a string, >which means 'test' has something to test for. depending on >the argument, it returns its exit code. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ No, in the '-z' example, I am NOT giveing a string. $test -z<CR> -- NOT $test -z<space><CR> ____________________________________________________________ Mr.Dean advised; So `test' is saying to itself "I have no arg2 to test against. Formally, arg2 does not exist ==> arg2 is not a string. Hence you get an automatic "false". ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Yes, I understand why $test -n<CR> returns 0. As you mentioned, no argment is different from no string. But this assumptions also apply '-z' option, isn't it? If so, $test -z<CR> should return 1 not 0, because `test' should say to itself (as in -z case) that I have no arg to test against, then it should return authentic `false'. I read comments from Mr.miLosh & Mr.Dean many time and tried test command in various patters many times. (I should have studied English harder!!) And finally I came up with a conclusion as Mr.which quotes; 'it is common in programms return a >0 value if a needed argument is missing.' So test returns 0 if no arg is given after -* option. Thus both $test -z<CR> and $test -n<CR> returns 0. Now I forced myself to be clear on this!! But why $test<CR> (no option, no args) returns 1 now, not 0!! I agagin have to force myself into thinking that it's a rule. """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" +---------+ * Get your own Jmail account.|URL= http://www.jmail.co.jp |--jmail--| * Get your own home page.|URL= http://www.servance.jp +---------+ * Get your own domain.|URL= http://domaintorou.com/ """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
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