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| -rw-r--r-- | sys-utils/pivot_root.8 | 75 |
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diff --git a/sys-utils/pivot_root.8 b/sys-utils/pivot_root.8 new file mode 100644 index 0000000..ea98f3b --- /dev/null +++ b/sys-utils/pivot_root.8 @@ -0,0 +1,75 @@ +.TH PIVOT_ROOT 8 "August 2011" "util-linux" "System Administration" +.SH NAME +pivot_root \- change the root filesystem +.SH SYNOPSIS +.B pivot_root +.I new_root put_old +.SH DESCRIPTION +\fBpivot_root\fP moves the root file system of the current process to the +directory \fIput_old\fP and makes \fInew_root\fP the new root file system. +Since \fBpivot_root\fP(8) simply calls \fBpivot_root\fP(2), we refer to +the man page of the latter for further details. + +Note that, depending on the implementation of \fBpivot_root\fP, root and +cwd of the caller may or may not change. The following is a sequence for +invoking \fBpivot_root\fP that works in either case, assuming that +\fBpivot_root\fP and \fBchroot\fP are in the current \fBPATH\fP: +.sp +cd \fInew_root\fP +.br +pivot_root . \fIput_old\fP +.br +exec chroot . \fIcommand\fP +.sp +Note that \fBchroot\fP must be available under the old root and under the new +root, because \fBpivot_root\fP may or may not have implicitly changed the +root directory of the shell. + +Note that \fBexec chroot\fP changes the running executable, which is +necessary if the old root directory should be unmounted afterwards. +Also note that standard input, output, and error may still point to a +device on the old root file system, keeping it busy. They can easily be +changed when invoking \fBchroot\fP (see below; note the absence of +leading slashes to make it work whether \fBpivot_root\fP has changed the +shell's root or not). +.SH OPTIONS +.TP +\fB\-V\fR, \fB\-\-version\fR +Display version information and exit. +.TP +\fB\-h\fR, \fB\-\-help\fR +Display help text and exit. +.SH EXAMPLE +Change the root file system to /dev/hda1 from an interactive shell: +.sp +.nf +mount /dev/hda1 /new-root +cd /new-root +pivot_root . old-root +exec chroot . sh <dev/console >dev/console 2>&1 +umount /old-root +.fi +.sp +Mount the new root file system over NFS from 10.0.0.1:/my_root and run +\fBinit\fP: +.sp +.nf +ifconfig lo 127.0.0.1 up # for portmap +# configure Ethernet or such +portmap # for lockd (implicitly started by mount) +mount \-o ro 10.0.0.1:/my_root /mnt +killall portmap # portmap keeps old root busy +cd /mnt +pivot_root . old_root +exec chroot . sh \-c 'umount /old_root; exec /sbin/init' \\ + <dev/console >dev/console 2>&1 +.fi +.SH SEE ALSO +.BR chroot (1), +.BR pivot_root (2), +.BR mount (8), +.BR switch_root (8), +.BR umount (8) +.SH AVAILABILITY +The pivot_root command is part of the util-linux package and is available from +https://www.kernel.org/pub/linux/utils/util-linux/. |