LSEEK(3spp)         RISC/os Reference Manual          LSEEK(3spp)



NAME
     lseek - move read/write pointer

SYNOPSIS
     #include <sys/file.h>

     #define LSET   0 /* set the seek pointer */
     #define LINCR  1 /* increment the seek pointer */

     int lseek(fd, offset, whence)
     int fd;
     offt offset;
     int whence;

DESCRIPTION
     The descriptor fd refers to a file or device open for read-
     ing and/or writing.  Lseek sets the file pointer of d as
     follows:

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

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

     Upon successful completion, the resulting pointer location
     is returned measured in bytes from beginning of the file.
     Some devices are incapable of seeking.  The value of the
     pointer associated with such a device is undefined.

RETURN VALUE
     Upon successful completion, the current file pointer value
     is returned.  Otherwise, a value of -1 is returned and errno
     is set to indicate the error.

ERRORS
     Lseek will fail and the file pointer will remain unchanged
     if:

     [EBADF]        fd is not an open file descriptor.

     [EINVAL]       whence is not a proper value.

SEE ALSO
     open(3spp)

BUGS
     This document's use of whence is incorrect English, but
     maintained for historical reasons.







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