LSEEK
Section: System Calls (2)
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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.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- SEE ALSO
-
- DIAGNOSTICS
-
- BUGS
-
- ASSEMBLER
-
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