chroot wrapper

chroot.sh

NEWROOT=`dirname $(readlink -f $0)`
read -n1 -p "chroot to $NEWROOT? (y/n) :" ack

[ foo"$ack" == fooy ] || exit -1

echo " "

function mount_if_not() {
   dir=$1
   mount | grep $NEWROOT$dir >/dev/null
   if [ $? -eq 0 ]; then
      echo Skipping mounting $dir
   else
      echo "Bind $dir to $NEWROOT$dir"
      mount --bind $dir $NEWROOT$dir
   fi
}

## for references
# /dev/sda2 on / type ext3 (rw,acl,user_xattr)
# proc on /proc type proc (rw)
# sysfs on /sys type sysfs (rw)
# devtmpfs on /dev type devtmpfs (rw,mode=0755)
# tmpfs on /dev/shm type tmpfs (rw,mode=1777)
# devpts on /dev/pts type devpts (rw,mode=0620,gid=5)
# fusectl on /sys/fs/fuse/connections type fusectl (rw)
# securityfs on /sys/kernel/security type securityfs (rw)
# none on /var/lib/ntp/proc type proc (ro,nosuid,nodev)
# /dev/mapper/datavg01-data01 on /data01 type ext4 (ro)

mount_if_not /proc
mount_if_not /sys
mount_if_not /dev
mount_if_not /dev/shm
mount_if_not /dev/pts

cp -f /etc/resolv.conf ${TARGET}/etc/

echo $NEWROOT > $NEWROOT/etc/debian_chroot
chroot $NEWROOT




function umount_dir () {
  dir=$1
  echo "Unbind $NEWROOT$dir"
  umount $NEWROOT$dir
}

read -n1 -p "Umount mapped filesystems (y/n) :" ack

echo " "
if [ foo"$ack" == fooy ]; then
  umount_dir /proc
  umount_dir /sys
  umount_dir /dev/pts
  umount_dir /dev/shm
  umount_dir /dev/
fi