.\"	$OpenBSD: revoke.2,v 1.14 2015/11/16 19:26:21 jmc Exp $
.\"	$NetBSD: revoke.2,v 1.3 1995/10/12 15:41:11 jtc Exp $
.\"
.\" Copyright (c) 1993
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.\"
.\" This code is derived from software contributed to Berkeley by
.\" Berkeley Software Design, Inc.
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.\" modification, are permitted provided that the following conditions
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.\"     @(#)revoke.2	8.1 (Berkeley) 6/4/93
.\"
.Dd $Mdocdate: November 16 2015 $
.Dt REVOKE 2
.Os
.Sh NAME
.Nm revoke
.Nd revoke file access
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn revoke "const char *path"
.Sh DESCRIPTION
The
.Fn revoke
function invalidates all current open file descriptors in the system
for the tty device named by
.Fa path .
Subsequent operations on any such descriptors
fail, with the exceptions that a
.Fn read
from a tty which has been revoked returns a count of zero (end of file),
and a
.Fn close
call will succeed.
If the file is a special file for a device which is open,
the device close function
is called as if all open references to the file had been closed.
.Pp
Access to a file may be revoked only by its owner or the superuser.
The
.Fn revoke
function is used to prepare a terminal device for a new login session,
preventing any access by a previous user of the terminal.
The
.Xr pty 4
subsystem has this as an implicit operation, but hardwired
.Xr tty 4
require the operation.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
Access to the named file is revoked unless one of the following:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Dv NAME_MAX
characters, or an entire pathname (including the terminating NUL)
exceeded
.Dv PATH_MAX
bytes.
.It Bq Er ENOENT
The named file or a component of the path name does not exist.
.It Bq Er ENOTTY
.Ar path
is not associated with a tty special device.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er EFAULT
.Fa path
points outside the process's allocated address space.
.It Bq Er EPERM
The caller is neither the owner of the file nor the superuser.
.El
.Sh SEE ALSO
.Xr close 2
.Sh HISTORY
The
.Fn revoke
function was introduced in
.Bx 4.3 Reno .