This is done by the shell, not the kerrnel. Look into shells to get your answer. The book 'Linux Application Develpment' goes through the steps of writing a shell and will answer your question completely. On Thursday 16 January 2003 2:05 am, Rupa wrote: > Hello, > I have very simple question. How kernel recognizes whether the command > given is valid or invalid. I mean whenever a invalid command is given, it > will display "bad command". I want to know whether it checks symbol table > for this information. If Iam wrong please correct me. > > Regards, > Rupa -- Tom Bradley Software Engineer Jaycor / Titan Systems -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/