pread

PREAD(2)		  Linux Programmer’s Manual		     PREAD(2)



NAME
       pread,  pwrite  -  read	from or write to a file descriptor at a given
       offset

SYNOPSIS
       #define _XOPEN_SOURCE 500

       #include <unistd.h>

       ssize_t pread(int fd, void *buf, size_t count, off_t offset);

       ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);

DESCRIPTION
       pread() reads up to count bytes from file descriptor fd at offset off-
       set (from the start of the file) into the buffer starting at buf.  The
       file offset is not changed.

       pwrite() writes up to count bytes from the buffer starting at  buf  to
       the  file  descriptor  fd  at  offset  offset.  The file offset is not
       changed.

       The file referenced by fd must be capable of seeking.

RETURN VALUE
       On success, the number of bytes read  or	 written  is  returned	(zero
       indicates  that	nothing was written, in the case of pwrite, or end of
       file, in the case of pread), or -1 on error, in which  case  errno  is
       set to indicate the error.

ERRORS
       pread  can  fail	 and  set errno to any error specified for read(2) or
       lseek(2).  pwrite can fail and set errno to any	error  specified  for
       write(2) or lseek(2).

CONFORMING TO
       Unix98

HISTORY
       The  pread  and	pwrite	system	calls  were added to Linux in version
       2.1.60; the entries in the  i386	 system	 call  table  were  added  in
       2.1.69.	 The libc support (including emulation on older kernels with-
       out the system calls) was added in glibc 2.1.

SEE ALSO
       read(2), write(2), lseek(2)



Linux 2.2.0-pre9		  1999-01-21			     PREAD(2)