ویرایش grub در حالت live CD ؟

it@it:~$ sudo fdisk -l

Disk /dev/sda: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x154a121d

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63   143364059    71681998+   7  HPFS/NTFS/exFAT
/dev/sda2       143364121   433854463   145245171+   f  W95 Ext'd (LBA)
/dev/sda3       433854464   482682879    24414208   83  Linux
/dev/sda4       482682880   488396799     2856960   82  Linux swap / Solaris
/dev/sda5       143364123   225279494    40957686    7  HPFS/NTFS/exFAT
/dev/sda6       225279558   307194929    40957686    7  HPFS/NTFS/exFAT
/dev/sda7       307197953   433854463    63328255+   7  HPFS/NTFS/exFAT

Disk /dev/sdb: 8053 MB, 8053063680 bytes
255 heads, 63 sectors/track, 979 cylinders, total 15728640 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x3a453965

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *        2048    15728639     7863296    b  W95 FAT32
it@it:~$ sudo mount /dev/sda3 /mnt
it@it:~$ sudo chroot /mnt
root@it:/# sudo mousepad /etc/default/grub
sudo: unable to resolve host it
No protocol specified

(mousepad:3529): Mousepad-ERROR **: Cannot open display:
root@it:/#