修改root密碼

虛拟機修改root密碼

1,挂載虛拟機的img 檔案

mount -o loop,offset=$((512*1060290)) vm.img /opt/

chroot /opt

one-node239:/# df

filesystem           1k-blocks      used available use% mounted on

/dev/xvda2             3662668   1127288   2535380  31% /

proc                   3662668   1127288   2535380  31% /proc

sysfs                  3662668   1127288   2535380  31% /sys

debugfs                3662668   1127288   2535380  31% /sys/kernel/debug

udev                   3662668   1127288   2535380  31% /dev

devpts                 3662668   1127288   2535380  31% /dev/pts

proc                   3662668   1127288   2535380  31% /var/lib/ntp/proc

one-node239:/# ls

bin  boot  dev  etc  home  lib  lib64  media  mnt  opt  proc  root  sbin  srv  sys  tmp  usr  var

one-node239:/# 

2，重挂根目錄，使之可讀寫

one-node239:/# mount -o remount,rw /

3，修改root密碼

a,如果此時改root密碼出現如下錯誤

one-node239:/etc# passwd 

changing password for root.

new password: 

bad password: too simple

reenter new password: 

cannot open /dev/urandom for reading: no such file or directory

cannot create salt for blowfish crypt

error: password not changed.

passwd: authentication token manipulation error

b,請執行以下步驟

exit 

mount --bind /dev/ /opt/dev/

chroot /opt/

one-node239:/# passwd 

password changed.

4,此時修改密碼成功,我們需要解除安裝目錄，重挂根，重新開機機器

 # umount /opt/

umount: /opt: device is busy.

        (in some cases useful info about processes that use

         the device is found by lsof(8) or fuser(1))

解除安裝報錯

umount /opt/dev/

umount /opt

5,重新開機輸入密碼，修改成功。