Lseek

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

Reposition the current file offset

namespace HH\Lib\OS;

function lseek(
  FileDescriptor $fd,
  int $offset,
  SeekWhence $whence,
): int;

See man 2 lseek for details. On error, an ErrnoException will be thrown.

Parameters

• FileDescriptor $fd
• int $offset
• SeekWhence $whence

Returns

• int