Slide 20 of 42

Notes:

Supply actual 2nd descriptor with dup2

- If fd2 is open, it is first closed

Fcntl - 4 different functions in 1

1. Duplicate

2. File descriptor flags - only 1 - FD_CLOEXEC - file is closed across an exec

3. File status flags - O_RDONLY, O_WRONLY, O_RDWR, O_APPEND, O_CREAT, O_TRUNC, O_EXCL, O_NONBLOCK
   -set: only O_APPEND and O_NONBLOCK can be changed

4. Record or range locking or byte locking

File Sharing

• Duplicating file descriptors - dup & dup2
• File management - fcntl
- Duplicate an existing file descriptor
- Get & set file descriptor flags
- Get & set file status flags
- Record locking