Handling files in Unix

• synchronous system calls
  • open(), read(), write(), close()
• open() returns a file descriptor
• read(), write(), and close() takes File Descriptor as an argument
• handling networking in C++ is also using File Descriptor for sockets.

Read

The return value can be:

• -1: error
• 0: EOF
• n: n bytes of data in the first n bytes of the buffer

Write

The return value can be:

• -1: error
• 0: write again with a new message
• n: n bytes of data in the first n bytes of the buffer are consumed by OS