# fcntl.h - [Overview](#section837157889165627) - [Summary](#section128064695165627) - [Macros](#define-members) - [Functions](#func-members) ## **Overview** **Related Modules:** [FS](FS.md) **Description:** Declares structures and functions used for file and directory operations such as opening a file, creating a file, and allocating space. **Since:** 1.0 **Version:** 1.0 ## **Summary** ## Macros

Macro Name and Value	Description
O_ACCMODE (03\|O_SEARCH)	Access mode.
O_RDONLY 00	Read-only.
O_WRONLY 01	Write-only.
O_RDWR 02	Read and write.
fallocate64 fallocate	Pre-allocates space to a file. See fallocate.

## Functions

Function	Description
creat (const char *path, mode_t mode)	int Creates a file or rewrites an existing file.
open (const char *path, int oflags,...)	int Opens a file.
fallocate (int fd, int mode, off_t offset, off_t len)	int Pre-allocates space to a file.
fcntl (int fd, int cmd,...)	int Manipulates a specified file descriptor.