Originální popis anglicky:
pread, pwrite - read from or write to a file descriptor at a given offset
Návod, kniha: Linux Programmer's Manual
#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);
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.
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.
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).
Unix98
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.
lseek(2),
read(2),
write(2)
