NAME

lseek − move read/write file pointer; seek

SYNOPSIS

#include <sys/types.h>
#include <unistd.h> off_t lseek (fildes, offset, whence)
int fildes;
off_t offset;
int whence;

DESCRIPTION

Lseek sets the file pointer associated with the file descriptor as follows:

If whence is SEEK_SET, the pointer is set to offset bytes. 

If whence is SEEK_CUR, the pointer is set to its current location plus offset.

If whence is SEEK_END, the pointer is set to the size of the file plus offset.

These symbolic constants are defined in <unistd.h>. 

RETURN VALUE

When lseek completes successfully, it returns a non-negative integer, which is the resulting file offset as measured in bytes from the beginning of the file.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

ERRORS

Lseek fails and the file offset remains unchanged if one or more of the following is true:

­[EBADF] Fildes is not an open file descriptor. 

­[ESPIPE] Fildes is associated with a pipe or FIFO. 

­[EINVAL and SIGSYS signal]
Whence is not one of the supported values. 

­[EINVAL] The resulting file offset would be negative. 

WARNINGS

Some devices are incapable of seeking.  The value of the file offset associated with such a device is undefined. 

Using lseek with a whence of SEEK_END on device special files is not supported and the results are not defined. 

SEE ALSO

creat(2), dup(2), fcntl(2), open(2), unistd(5). 

STANDARDS CONFORMANCE

lseek: SVID2, XPG2, XPG3, POSIX.1, FIPS 151-1

Hewlett-Packard Company  —  HP-UX Release 7.0: Sept 1989