Passing pointers to struct Post: 302486469

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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 offset (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 without 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)

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