DUP(3)DUP(3)NAMEdup - dups of open files
SYNOPSIS
bind #d /fd
/fd/0
/fd/0ctl
/fd/1
/fd/1ctl
...
DESCRIPTION
The dup device serves a one-level directory containing files whose
names are decimal numbers. Each such file also has an associated con‐
trol file. A file of name n corresponds to open file descriptor n in
the current process.
A sys-open(2) of file n results in a file descriptor identical to what
would be returned from a system call sys->dup(n, -1). Note that the
result is no longer a file in the dup device.
The stat operation returns information about the device file, not the
open file it points to. A stat of #d/n will contain n for the name, 0
for the length, and 400, 200, or 600 (octal) for the mode, depending on
whether the dup target is open for reading, writing, or both.
A file of name nctl may be read to discover the properties of the asso‐
ciated file descriptor, in format identical to that of the fd file in
prog(3).
SEE ALSOsys-dup(2)SOURCE
/usr/inferno/emu/port/devdup.c
/usr/inferno/os/port/devdup.c
DUP(3)