+++ /dev/null
-.\" Copyright (C) 2000 by Werner Almesberger
-.\"
-.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
-.\" May be distributed under GPL
-.\" %%%LICENSE_END
-.\"
-.\" Written 2000-02-23 by Werner Almesberger
-.\" Modified 2004-06-17 Michael Kerrisk <mtk.manpages@gmail.com>
-.\"
-.TH PIVOT_ROOT 2 2012-07-13 "Linux" "Linux Programmer's Manual"
-.SH NAME
-pivot_root \- change the root filesystem
-.SH SYNOPSIS
-.BI "int pivot_root(const char *" new_root ", const char *" put_old );
-
-.IR Note :
-There is no glibc wrapper for this system call; see NOTES.
-.SH DESCRIPTION
-.BR pivot_root ()
-moves the root filesystem of the calling process to the
-directory \fIput_old\fP and makes \fInew_root\fP the new root filesystem
-of the calling process.
-.\"
-.\" The
-.\" .B CAP_SYS_ADMIN
-.\" capability is required.
-
-The typical use of
-.BR pivot_root ()
-is during system startup, when the
-system mounts a temporary root filesystem (e.g., an \fBinitrd\fP), then
-mounts the real root filesystem, and eventually turns the latter into
-the current root of all relevant processes or threads.
-
-.BR pivot_root ()
-may or may not change the current root and the current
-working directory of any processes or threads which use the old
-root directory.
-The caller of
-.BR pivot_root ()
-must ensure that processes with root or current working directory
-at the old root operate correctly in either case.
-An easy way to ensure this is to change their
-root and current working directory to \fInew_root\fP before invoking
-.BR pivot_root ().
-
-The paragraph above is intentionally vague because the implementation
-of
-.BR pivot_root ()
-may change in the future.
-At the time of writing,
-.BR pivot_root ()
-changes root and current working directory of each process or
-thread to \fInew_root\fP if they point to the old root directory.
-This
-is necessary in order to prevent kernel threads from keeping the old
-root directory busy with their root and current working directory,
-even if they never access
-the filesystem in any way.
-In the future, there may be a mechanism for
-kernel threads to explicitly relinquish any access to the filesystem,
-such that this fairly intrusive mechanism can be removed from
-.BR pivot_root ().
-
-Note that this also applies to the calling process:
-.BR pivot_root ()
-may
-or may not affect its current working directory.
-It is therefore recommended to call
-\fBchdir("/")\fP immediately after
-.BR pivot_root ().
-
-The following restrictions apply to \fInew_root\fP and \fIput_old\fP:
-.IP \- 3
-They must be directories.
-.IP \- 3
-\fInew_root\fP and \fIput_old\fP must not be on the same filesystem as
-the current root.
-.IP \- 3
-\fIput_old\fP must be underneath \fInew_root\fP, that is, adding a nonzero
-number of \fI/..\fP to the string pointed to by \fIput_old\fP must yield
-the same directory as \fInew_root\fP.
-.IP \- 3
-No other filesystem may be mounted on \fIput_old\fP.
-.PP
-See also
-.BR pivot_root (8)
-for additional usage examples.
-
-If the current root is not a mount point (e.g., after
-.BR chroot (2)
-or
-.BR pivot_root (),
-see also below), not the old root directory, but the
-mount point of that filesystem is mounted on \fIput_old\fP.
-
-\fInew_root\fP does not have to be a mount point.
-In this case,
-\fI/proc/mounts\fP will show the mount point of the filesystem containing
-\fInew_root\fP as root (\fI/\fP).
-.SH RETURN VALUE
-On success, zero is returned.
-On error, \-1 is returned, and
-\fIerrno\fP is set appropriately.
-.SH ERRORS
-.BR pivot_root ()
-may return (in \fIerrno\fP) any of the errors returned by
-.BR stat (2).
-Additionally, it may return:
-.TP
-.B EBUSY
-\fInew_root\fP or \fIput_old\fP are on the current root filesystem,
-or a filesystem is already mounted on \fIput_old\fP.
-.TP
-.B EINVAL
-\fIput_old\fP is not underneath \fInew_root\fP.
-.TP
-.B ENOTDIR
-\fInew_root\fP or \fIput_old\fP is not a directory.
-.TP
-.B EPERM
-The calling process does not have the
-.B CAP_SYS_ADMIN
-capability.
-.SH VERSIONS
-.BR pivot_root ()
-was introduced in Linux 2.3.41.
-.SH CONFORMING TO
-.BR pivot_root ()
-is Linux-specific and hence is not portable.
-.SH NOTES
-Glibc does not provide a wrapper for this system call; call it using
-.BR syscall (2).
-.SH BUGS
-.BR pivot_root ()
-should not have to change root and current working directory of all other
-processes in the system.
-
-Some of the more obscure uses of
-.BR pivot_root ()
-may quickly lead to
-insanity.
-.SH SEE ALSO
-.BR chdir (2),
-.BR chroot (2),
-.BR stat (2),
-.BR initrd (4),
-.BR pivot_root (8)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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