Moves the file pointer to a location specified as an offset from the origin in a file.

#include <unistd.h>

off_t lseek (int handle, off_t offset, int origin);

long64 _lseek64 (int handle, long64 offset, int origin);

Parameters

handle

Descriptor referring to an open file.

offset

Number of bytes from origin, specified as one of these constants, or beyond end-of-file.

Value	Description
SEEK_SET	Beginning of file.
SEEK_CUR	Current position of file pointer.
SEEK_END	End of file.
origin	Initial position.

Remarks

The next operation on the file occurs at the new location.

lseek can reposition the pointer anywhere in a file and beyond the end of the file. An attempt to position the pointer before the beginning of the file causes an error.

Results are undefined on devices incapable of seeking, like terminals and printers.

Return Values

The offset, in bytes, of the new position from the beginning of the file.

Success.

-1L and the function sets errno to one of these values:

EBADF	Invalid file descriptor.
EINVAL	Invalid value for origin, or position specified by offset is before the beginning of the file.
EIMPL	Library call is not implemented in the current configuration

Failure.

Requirements