NAME

lseek − move read/write file pointer

SYNOPSIS

long lseek (fildes, offset, whence)
int fildes;
long offset;
int whence;

DESCRIPTION

fildes is a file descriptor returned from a creat, open, dup, or fcntl system call.  lseek sets the file pointer associated with fildes as follows:

If whence is 0, the pointer is set to offset bytes. 

If whence is 1, the pointer is set to its current location plus offset.

If whence is 2, the pointer is set to the size of the file plus offset.

Upon successful completion, the resulting pointer location, as measured in bytes from the beginning of the file, is returned.  Note that if fildes is a remote file descriptor and offset is negative, lseek returns the file pointer even if it is negative. 

lseek fails and the file pointer remains unchanged if one or more of the following are 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 0, 1, or 2. 

­[EINVAL] fildes is not a remote file descriptor, and the resulting file pointer would be negative. 

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

SEE ALSO

creat(2), dup(2), fcntl(2), open(2). 

DIAGNOSTICS

Upon successful completion, a non-negative integer indicating the file pointer value is returned.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

September 02, 1992