_llseek — reposition read/write file offset


#include <sys/types.h>
#include <unistd.h>

int _llseek(unsigned int fd, unsigned long offset_high,
            unsigned long offset_low, loff_t *result,
            unsigned int whence);

Note: There is no glibc wrapper for this system call; see Notes.


The _llseek() system call repositions the offset of the open file description associated with the file descriptor fd to (offset_high<<32) | offset_low bytes relative to the beginning of the file, the current file offset, or the end of the file, depending on whether whence is SEEK_SET, SEEK_CUR, or SEEK_END, respectively. It returns the resulting file position in the argument result.

This system call exists on various 32-bit platforms to support seeking to large file offsets.

Return Value

Upon successful completion, _llseek() returns 0. Otherwise, a value of -1 is returned and errno is set to indicate the error.



fd is not an open file descriptor.


Problem with copying results to user space.


whence is invalid.

Conforming to

This function is Linux-specific, and should not be used in programs intended to be portable.


Glibc does not provide a wrapper for this system call. To invoke it directly, use syscall(2). However, you probably want to use the lseek(2) wrapper function instead.

See Also

lseek(2), open(2), lseek64(3)


This page is part of release 5.04 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Referenced By

lseek64(3), syscall(2), syscalls(2).

The man page _llseek(2) is an alias of llseek(2).

2017-09-15 Linux Programmer's Manual