Programming

Hi,

I am implementing a shell in C, with the following problem...

Suppose the shell is invoked from the command line as
>> myshell < test.in > test.out 2>&1

I have to execute the commands in test.in and redirect them to test.out
How does one detect in the main function that the shell has been
invoked with input and
output redirection files? Invoking it thus, I do not get any parameters
in argv[].
Also can one detect the "2>&1" part to direct stderr to stdout?

Some other program, an instance of ksh perhaps, had to present the ">> " prompt and process the response. This "outer" shell is responsible for setting up stdin, stdout, and stderr. They will be ready for use before "myshell" is exec'ed. So myshell will simply read from stdin, which in this case will be test.in. And stdout (and stderr) are ready for writing as well.