Chroot - Revision history

Christoph: /* Copy files while in Rescue Mode */

2020-07-01T07:21:45Z

‎Copy files while in Rescue Mode

Christoph at 13:33, 3 November 2014

2014-11-03T13:33:43Z

Christoph: /* Copy files while in Rescue Mode */

2014-11-03T12:40:21Z

‎Copy files while in Rescue Mode

Christoph: New page: A '''chroot''' on Linux operating systems is an operation that changes the apparent root directory for the current running process and its children. The modified environment is called ...

2014-11-03T12:39:16Z

New page: A '''chroot''' on Linux operating systems is an operation that changes the apparent root directory for the current running process and its children. The modified environment is called ...

New page

A '''chroot''' on [[Linux]] operating systems is an operation that changes the apparent root directory for the current running process and its children. The modified environment is called a "chroot jail".

==Copy files while in Rescue Mode==
''Note: The following section shows how to copy files from a [[:Category:Rackspace]] Cloud Server while in Rescue Mode.''

* Find out which is your "real" root device (i.e., the one that is not the Rescue Mode's root device / the one already mounted):
$ fdisk -l

* Mount "real" root device and required filesystem dirs:
$ mount /dev/xvdb1 /mnt
$ mount -o bind /dev /mnt/dev
$ mount -o bind /sys /mnt/sys
$ mount -o bind /dev/shm /mnt/dev/shm
$ mount -o bind /proc /mnt/proc
$ #***** OR *****:
$ mount /dev/xvdb1 /mnt
$ mount -t proc none /mnt/proc
$ mount --rbind /sys /mnt/sys
$ mount --rbind /dev /mnt/dev

* Set up networking for your chrooted jail:

$ ln -s /etc/resolv.conf /mnt/etc/resolv.conf

* Chroot into your jail:

$ chroot /mnt /bin/bash

* Copy the files to a remote/destination server:
$ rsync -avr /path/to/data/dir user@x.x.x.x:/path/to/dest/data/dir

* Exit the chrooted jail
$ sync
$ exit
$ umount -lf /mnt/{dev,sys,proc}
$ umount /mnt

Finally, exit "Rescue Mode" and you are done.

==Converting a root filesystem to ext4==
''Note: The following section shows how to convert the root filesystem from ext3 to ext4 on a [[:Category:Rackspace]] Cloud Server while in Rescue Mode.''

* Assuming your root device is <code>/dev/xvda1</code>, before you enter Rescue Mode, change your <code>/etc/fstab</code> entry for root from:
/dev/xvda1 / ext3 errors=remount-ro,noatime,barrier=0 0 1
to:
/dev/xvda1 / ext4 errors=remount-ro,noatime,barrier=0 0 1

then enter Rescue Mode (do ''not'' reboot your server before entering Rescue Mode).

* While in Rescue Mode, find out which device is your "real" root device (i.e., not the Rescue Mode's root device):
$ fdisk -l

* Then run a filesystem check on the "real" root filesystem:
$ fsck.ext3 -pf /dev/xvdb1

* Enable all the ext4 features on the root filesystem:
$ tune2fs -O extents,uninit_bg,dir_index /dev/xvdb1

* Run another filesystem check on the root filesystem (it will most likely find and fix errors. This is completely normal):
$ fsck.ext4 -yfD /dev/xvdb1

You should now be able to exit Rescue Mode and your root filesystem will be using ext4.

[[Category:Linux Command Line Tools]]

@@ Line 13: / Line 13: @@
   $ mount -o bind /dev/shm /mnt/dev/shm
   $ mount -o bind /proc /mnt/proc
-  $ #***** OR *****:
+  #***** OR *****:
   $ mount /dev/xvdb1 /mnt
   $ mount -t proc none /mnt/proc

@@ Line 2: / Line 2: @@
 ==Copy files while in Rescue Mode==
-''Note: The following section shows how to copy files from a [[:Category:Rackspace]] Cloud Server while in Rescue Mode.''
+''Note: The following section shows how to copy files from a [[:Category:Rackspace|Rackspace]] Cloud Server while in Rescue Mode.''
 * Find out which is your "real" root device (i.e., the one that is not the Rescue Mode's root device / the one already mounted):
@@ Line 39: / Line 39: @@
 ==Converting a root filesystem to ext4==
-''Note: The following section shows how to convert the root filesystem from ext3 to ext4 on a [[:Category:Rackspace]] Cloud Server while in Rescue Mode.''
+''Note: The following section shows how to convert the root filesystem from ext3 to ext4 on a [[:Category:Rackspace|Rackspace]] Cloud Server while in Rescue Mode.''
 * Assuming your root device is <code>/dev/xvda1</code>, before you enter Rescue Mode, change your <code>/etc/fstab</code> entry for root from:

@@ Line 27: / Line 27: @@
   $ chroot /mnt /bin/bash
-* Copy the files to a remote/destination server:
+* Copy the files to a remote/destination server (using [[rsync]]):
-  $ rsync -avr /path/to/data/dir user@x.x.x.x:/path/to/dest/data/dir
+  $ rsync -e 'ssh -p 22' -avl --stats --progress /path/to/data/dir user@x.x.x.x:/path/to/dest/data/dir
-−
 * Exit the chrooted jail
   $ sync