Using the POSIX API:

The system-call sequence for this program (which copies the contents of a source file to the destination file) is shown below. source file destination file Example System Call Sequence Acquire input file name Write prompt to screen Accept input Acquire output file name Write prompt to screen Accept input Open the input file if file doesn't exist, abort Create output file if file exists, abort Loop Read from input file Write to output file Until read fails Close output file Write completion message to screen Terminate normally