Will copy one line of the standard input to standard output.

These represent the "standard" input and output channels that have been established for the process.

If no file is specified then standard input will be used.

Each child process first s the appropriate pipe file descriptor to either its standard input or output.

Commands like and can accept the standard input as a parameter, or argument by using a pipe.

There is also an option to read one file (but not both) from standard input.

If the response from the standard input begins with the character'y' or 'Y', the move is attempted.

The way to account for all that is with a standard input!

If no files are specified, cat reads from standard input only.

Interaction is done through the child's standard input and output.