this picture for print You didn't do the question. Go back.
if $1 = 0
but until now it give me this message [: 11: missing ]
what i should be do ?
if [ -z "$1" (space needed here) ]
When you test -z you expect an empty (NULL) value. You should to put it in quotes.
The [ ] characters have to have at least one space on each side of them. They are actually keywords in shell.
Thank you very much.
for helping me.