.\" Copyright (C) 2006, Janak Desai <janak@us.ibm.com>
.\" and Copyright (C) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Licensed under the GPL
.\"
.\" Patch Justification:
.\" unshare system call is needed to implement, using PAM,
.\" per-security_context and/or per-user namespace to provide
.\" polyinstantiated directories. Using unshare and bind mounts, a
.\" PAM module can create private namespace with appropriate
.\" directories(based on user's security context) bind mounted on
.\" public directories such as /tmp, thus providing an instance of
.\" /tmp that is based on user's security context. Without the
.\" unshare system call, namespace separation can only be achieved
.\" by clone, which would require porting and maintaining all commands
.\" such as login, and su, that establish a user session.
.\"
.\" FIXME Document CLONE_NEWIPC, which is new in 2.6.18
.\" FIXME Document CLONE_NEWUTS, which is new in 2.6.19
.\"
.\" Japanese Version Copyright (c) 2006 Yuichi SATO
.\"         all rights reserved.
.\" Translated 2006-08-10 by Yuichi SATO <ysato444@yahoo.co.jp>, LDP v2.36
.\"
.TH UNSHARE 2 2007-07-26 "Linux" "Linux Programmer's Manual"
.SH ̾
unshare \- ץ¹ԥƥȤΰʬΥ
.SH 
.nf
.B #define _GNU_SOURCE
.\" Actually _BSD_SOURCE || _SVID_SOURCE
.\" See http://sources.redhat.com/bugzilla/show_bug.cgi?id=4749
.B #include <sched.h>
.sp
.BI "int unshare(int " flags );
.fi
.SH 
.BR unshare ()
Ȥȡץ¾Υץȸ߶ͭƤ
¹ԥƥȤΰʬΥ뤳ȤǤ롣
¹ԥƥȤΰȤ֤̾ʤɤϡ
ץ
.BR fork (2)
ޤ
.BR vfork (2)
ȤäȤˡۤΤ˶ͭ롣
ۥʤɤϡ
.BR clone (2)
ȤäƥץȤˡŪ˶ͭ뤳Ȥ׵Ǥ롣

.BR unshare ()
μˡϡץץ뤳Ȥʤ
ͭ¹ԥƥȤ椹뤳ȤǤ롣

.I flags
ϥӥåȥޥǤꡢ
¹ԥƥȤΤɤʬζͭ뤫ɽ
ΰϡʲ 0 İʾ OR ǻꤹ:
.TP
.B CLONE_FILES
.BR clone (2)
.B CLONE_FILES
ե饰θ̤ä
եǥץơ֥ͭ
ƤӽФץ¾Υץȥեǥץͭʤʤ롣
.TP
.B CLONE_FS
.BR clone (2)
.B CLONE_FS
ե饰θ̤ä
ե륷ƥ°ͭ
ƤӽФץ¾Υץȥ롼ȥǥ쥯ȥꡦ
ȥǥ쥯ȥꡦumask °ͭʤʤ롣
.BR chroot (2),
.BR chdir (2),
.BR umask (2)
˱ƶ롣
.TP
.B CLONE_NEWNS
.\" These flag name are inconsistent:
.\" CLONE_NEWNS does the same thing in clone(), but CLONE_VM,
.\" CLONE_FS, and CLONE_FILES reverse the action of the clone()
.\" flags of the same name.
Υե饰
.BR clone (2)
.B CLONE_NEWNS
ե饰\fIƱ\fR̤ġ
֤̾ͭƤӽФץ
¾ΥץȤ϶ͭʤ֤ͭ̾Υԡġ
Υե饰ꤹȡ
.B CLONE_FS
ۤΤ˻ꤵ롣
.\" As at 2.6.16, the following forced implications also apply,
.\" although the relevant flags are not yet implemented.
.\" If CLONE_THREAD is set force CLONE_VM.
.\" If CLONE_VM is set, force CLONE_SIGHAND.
.\" If CLONE_SIGHAND is set and signals are also being shared
.\" (i.e., current->signal->count > 1), force CLONE_THREAD.
.\"
.\" FIXME . CLONE_VM is not (yet, as at 2.6.16) implemented.
.\" .TP
.\" .B CLONE_VM
.\" Reverse the effect of the
.\" .BR clone (2)
.\" .B CLONE_VM
.\" flag.
.\" .RB ( CLONE_VM
.\" is also implicitly set by
.\" .BR vfork (2),
.\" and can be reversed using this
.\" .BR unshare ()
.\" flag.)
.\" Unshare virtual memory, so that the calling process no
.\" longer shares its virtual address space with any other process.
.PP
.I flags
 0 ꤵ줿硢
.BR unshare ()
ϲԤʤΤǡ
ƤӽФץμ¹ԥƥȤϡѹʤ
.SH ֤
 0 ֤롣
Ԥ \-1 ֤ơ
.I errno
ˤϥ顼򼨤ͤꤵ롣
.SH 顼
.TP
.B EINVAL
.I flags
ʥӥåȤꤵ줿
.TP
.B ENOMEM
ƤӽФΥƥȤΤͭɬפʬ򥳥ԡ뤿ˡ
ʬʥ꤬ݤǤʤä
.TP
.B EPERM
.I flags

.B CLONE_NEWNS
ꤵ줿ƤӽФץø
.RB ( CAP_SYS_ADMIN
ѥӥƥ) ʤä
.SH С
.BR unshare ()
ƥॳ Linux ͥ 2.6.16 ɲä줿
.SH 
.BR unshare ()
ƥॳ Linux ͭǤ롣
.SH 
.BR clone (2)
ǿץȤ˶ͭƤΥץ°
.BR unshare ()
ˤäƶͭβǤ櫓ǤϤʤ
äˡͥ 2.6.16 ˤƤϡ
.BR unshare ()

.BR CLONE_SIGHAND ,
.\" However, we can do unshare(CLONE_SIGHAND) if CLONE_SIGHAND
.\" was not specified when doing clone(); i.e., unsharing
.\" signal handlers is permitted if we are not actually
.\" sharing signal handlers.   mtk
.BR CLONE_SYSVSEM ,
.BR CLONE_THREAD ,
.\" FIXME . check future kernel versions (e.g., 2.6.17)
.\" to see if CLONE_VM gets implemented.
.B CLONE_VM
θ̤äΥե饰Ƥʤ
.\" However, as at 2.6.16, we can do unshare(CLONE_VM) if CLONE_VM
.\" was not specified when doing clone(); i.e., unsharing
.\" virtual memory is permitted if we are not actually
.\" sharing virtual memory.   mtk
εǽϡɬפǤоɲä뤫⤷ʤ
.\"
.\"9) Future Work
.\"--------------
.\"The current implementation of unshare does not allow unsharing of
.\"signals and signal handlers. Signals are complex to begin with and
.\"to unshare signals and/or signal handlers of a currently running
.\"process is even more complex. If in the future there is a specific
.\"need to allow unsharing of signals and/or signal handlers, it can
.\"be incrementally added to unshare without affecting legacy
.\"applications using unshare.
.\"
.SH Ϣ
.BR clone (2),
.BR fork (2),
.BR vfork (2),
Documentation/unshare.txt