> > Does any body have any idea ? > shure . It simple . What I'm writting here is quite simplification, but still describes the problem. When you do man you usually do something like nroff -man "file" |less . Whenever you exit from less with q nroff dies with "broken pipe" signal. You can see allmost any unix programming book about it. I suggest Stivens "Advanced Programming in Unix Enviroment" . Meir