lseek(2)                                                       lseek(2)

  lseek()

  NAME

    lseek() - reposition read/write file offset

  SYNOPSIS

    #include 

    off_t lseek (int fd, off_t offset, int whence)

  DESCRIPTION

    The lseek(2) function repositions the offset of the file descriptor fd to
    the argument offset according to the directive whence. The argument fd
    must be an open file descriptor. The lseek(2) function repositions the
    file pointer fd as follows:
    *     If whence is SEEK_SET, the offset is set to offset bytes.
    *     If whence is SEEK_CUR, the offset is set to its current location
          plus offset bytes.
    *     If whence is SEEK_END, the offset is set to the size of the file
          plus offset bytes.

    The lseek(2) function allows the file offset to be set beyond the end of
    the existing end-of-file of the file. If data is later written at this
    point, subsequent reads of the data in the gap return bytes of zeros
    (until data is actually written into the gap).

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

  RETURN VALUES

    Upon successful completion, lseek(2) returns the resulting offset location
    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

    The lseek(2) call will fail and the file pointer will remain unchanged if:

    [EBADF]
        Fd is not an open file descriptor.

    [ESPIPE]
        Fd is associated with a pipe, socket, or FIFO.

    [EINVAL]
        Whence is not a proper value.

  SEE ALSO

    dup(2)

    fseek(3)

    open(2)

  USAGE NOTES

    The lseek function is thread safe.

    The lseek function is async-signal safe.