Hi, This is implemented by shell internally, The parser of shell is intelligent enough to detect that these are shell facilities ,it invokes system call like chdir in case of cd. And in pwd it extracts the PWD variable from the symbol table maintained by shell,in the form of value=variable format,shoot export command on the shell and see this symbol table. Many other things are facilites of shell itself. Like execution of commands in background, Aliasing,Shell scripting,History command which is invoked by pressing up or down arrow key ,pipes,I/O redirection and many more. This man clear your doubt. Thanks Prasanna --- Jagadeesh Bhaskar P <jbhaskar@xxxxxxxxxxxx> wrote: > In TLDP tutorial about the kernel, it is saying that > all shell commands > except cd and pwd are binary executables. If cd and > pwd are not so, then > what are they?? > > > NB: Mail server was down yesterday :-( . If someone > had replied for this > pls do resend it. > > -- > With regards, > > Jagadeesh Bhaskar P > R&D Engineer > HCL Infosystems Ltd > Pondicherry > > > -- > Kernelnewbies: Help each other learn about the Linux > kernel. > Archive: > http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > > __________________________________ Do you Yahoo!? The all-new My Yahoo! - Get yours free! http://my.yahoo.com -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
