NAME
dup – 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 control file. A file of name n corresponds to open file descriptor n in the current process.

An open(2) of file n results in a file descriptor identical to what would be returned from a system call 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 0400, 0200, or 0600 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 associated file descriptor, in format identical to that of the fd file in proc(3).

SEE ALSO
dup(2)

SOURCE
/sys/src/9/port/devdup.c
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