unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (v7man)
Page:
Section:
Apropos / Subsearch:
optional field

LSEEK(2)                      System Calls Manual                     LSEEK(2)



NAME
       lseek, tell - move read/write pointer

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

       long tell(fildes)

DESCRIPTION
       The  file descriptor refers to a file open for reading or writing.  The
       read (resp. write) pointer for the file is set 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.

       The returned value is the resulting pointer location.

       The obsolete function tell(fildes) is identical  to  lseek(fildes,  0L,
       1).

       Seeking  far  beyond  the end of a file, then writing, creates a gap or
       `hole', which occupies no physical space and reads as zeros.

SEE ALSO
       open(2), creat(2), fseek(3)

DIAGNOSTICS
       -1 is returned for an undefined file descriptor, seek  on  a  pipe,  or
       seek to a position before the beginning of file.

BUGS
       Lseek is a no-op on character special files.

ASSEMBLER
       (lseek = 19.)
       (file descriptor in r0)
       sys lseek; offset1; offset2; whence

       Offset1  and  offset2  are  the high and low words of offset; r0 and r1
       contain the pointer upon return.



                                                                      LSEEK(2)