Confused? [Z] $EDITOR whether air test environment variables Echo $? Why no matter what is behind the document, the final results were 0 Confused? [code] $EDITOR] Or [z]] [[z $EDITOR Order itself (shell built), $? [[]] operation is successful. So 0 [Z], named $EDITOR echo "no editor env variable! " Incidentally, you EDITOR is to test whether the air, that is to say, it might be empty. [Z] $EDITOR EDITOR space in the present circumstances, even grammatical mistakes. [X] = X$EDITOR, named echo "no editor env variable! " This test will be suitable for some of you [/code] Confused? I am afraid the answer to the second floor there is a problem, [or] condiction condiction return value is not test the success of the implementation of the order, but the real test conditions condiction. As [z] If you $EDITOR $EDITOR return 0 otherwise return to empty one. Confused? [Z], named echo true | | echo false $EDITOR Confused? [ Closed window ]