ref: d1540c7f666e3c5d636b48c956b444205b50502d
dir: /man/3/dup/
.TH DUP 3 .SH NAME dup \- dups of open files .SH SYNOPSIS .nf .B bind #d /fd .B /fd/0 .B /fd/0ctl .B /fd/1 .B /fd/1ctl \&... .fi .SH DESCRIPTION The .I 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 .I n corresponds to open file descriptor .I n in the current process. .PP A .IR sys-open (2) of file .I n results in a file descriptor identical to what would be returned from a system call .BI sys->dup( n, .BR -1) . Note that the result is no longer a file in the .I dup device. .PP The .I stat operation returns information about the device file, not the open file it points to. A stat of .BI #d/ n will contain .I 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. .PP A file of name .IB n ctl may be read to discover the properties of the associated file descriptor, in format identical to that of the .B fd file in .IR prog (3). .SH SEE ALSO .IR sys-dup (2) .SH SOURCE .B /usr/inferno/emu/port/devdup.c .br .B /usr/inferno/os/port/devdup.c