---
title: Adopting Swift File Options
framework: system
role: article
role_heading: Article
path: system/adopting-file-options
---

# Adopting Swift File Options

Migrate existing C code to Swift, using the file-operation options provided by the System module.

## Overview

Overview The C options for how to open a file map to Swift as follows: O_RDONLY ⟶ readOnly O_WRONLY ⟶ writeOnly O_RDWR ⟶ readWrite The C constants for specifying options when opening a file map to Swift as follows: O_NONBLOCK ⟶ nonBlocking O_APPEND ⟶ append O_CREAT ⟶ create O_TRUNC ⟶ truncate O_EXCL ⟶ exclusiveCreate O_SHLOCK ⟶ sharedLock O_EXLOCK ⟶ exclusiveLock O_NOFOLLOW ⟶ noFollow O_SYMLINK ⟶ symlink O_EVTONLY ⟶ eventOnly O_CLOEXEC ⟶ closeOnExec The C constants for specify seek offsets map to Swift as follows: SEEK_SET ⟶ start SEEK_CUR ⟶ current SEEK_END ⟶ end SEEK_HOLE ⟶ nextHole SEEK_DATA ⟶ nextData

## See Also

### Adopting System

- [Adopting Swift File Operations](system/adopting-file-operations.md)
- [Adopting Swift Error Constants](system/adopting-errno.md)