While I have shown some fairly complex patterns, real patterns are usually pretty simple. In fact, sometimes other issues can make the patterns seem like the easy part of writing scripts.
rsh program executes a command on a remote host. For example, the following command executes the command "
quack twice" on host
rsh duck quack twice
quack is a mythical program, you can imagine it shares a trait common to many programs. Namely,
quack reports its status by returning an exit value. If
quack works correctly, it exits with the value 0 (which by convention means success). Otherwise it exits with the value 1 (failure). From the C-shell, the status of the last command is stored in the variable
status. I can demonstrate a successful interactive invocation by interacting directly with the C-shell.
quack is executed via
rsh, the same
echo command will not provide the exit status of
quack. In fact,
rsh does not provide any way of returning the status of a command. Checking the value of
status after running
rsh tells you only whether
rsh itself ran successfully. The status of
rsh is not really that useful. It reports problems such as "
unknown host" if you give it a bogus host. But if
rsh locates the host and executes the command, that is considered a success and 0 is returned no matter what happens inside the command. In fact, the
rsh is considered a success even if the command is not ...