sudo mkdir -p /mnt/runimg
pi@raspberry4:~ $ sudo mount --bind /media/netdir/raspbrreyPi/mnt_runimg    /mnt/runimg
pi@raspberry4:~ $ ls -l /mnt/runimg/
total 85492736
-rwxrwxrwx+ 1               99   99  4555014144 Jan  7 22:32 2019-04-08-raspbian-stretch_chroot.img
-rwxrwxrwx+ 1 systemd-timesync   98  3481272320 Mar 23 22:09 2019-04-08-raspbian-stretch-make-new.img
-rwxrwxrwx+ 1 root             root  3481272320 Dec 30 09:55 2019-04-08-raspbian-stretch-make-old.img
-rwx------+ 1               99   99  3829399552 Jan 26 21:38 2019-09-26-raspbian-buster_jin.img
-rw-r--r--+ 1 root             root  5934940160 Apr 13 22:23 2020-02-13-raspbian-buster_jin-make.img
-rw-rw-rw-+ 1 root             root 31180455936 Apr 14 20:39 aarch64_bak.img
-rw-rw-rw-+ 1 root             root 31180455936 Apr 14 20:39 aarch64.img
drwxrwxrwx+ 1 root             root         160 Dec 19 22:41 bak
-rw-rw-rw-+ 1               99   99  1728053248 Mar 25 22:50 readynas_compile_tool2.img
-rw-rw-rw-+ 1               99   99  2173698048 Jan  8 23:25 readynas_compile_tool.img
pi@raspberry4:~ $ sudo mkdir -p ~/rpi_mnt
pi@raspberry4:~ $ sudo losetup -f -P --show /mnt/runimg/aarch64.img
/dev/loop0
pi@raspberry4:~ $ sudo mount /dev/loop0p2 -o rw ~/rpi_mnt
pi@raspberry4:~ $ cd ~/rpi_mnt
pi@raspberry4:~/rpi_mnt $ sudo mount /dev/loop0p1 -o rw ~/rpi_mnt/boot/
pi@raspberry4:~/rpi_mnt $ sudo mount --bind /dev ~/rpi_mnt/dev/
pi@raspberry4:~/rpi_mnt $ sudo mount --bind /sys ~/rpi_mnt/sys/
pi@raspberry4:~/rpi_mnt $ sudo mount --bind /proc ~/rpi_mnt/proc/
pi@raspberry4:~/rpi_mnt $ sudo mount --bind /dev/pts ~/rpi_mnt/dev/pts
pi@raspberry4:~/rpi_mnt $ sudo mkdir -p  /media/netdir/source/raspberrypi/4-08_new_raspi
pi@raspberry4:~/rpi_mnt $ sudo mkdir -p  ~/rpi_mnt/mnt/compile
pi@raspberry4:~/rpi_mnt $ sudo mount  --bind  /media/netdir/source/raspberrypi/4-08_new_raspi ~/rpi_mnt/mnt/compile
pi@raspberry4:~/rpi_mnt $ cd ~/rpi_mnt
pi@raspberry4:~/rpi_mnt $ sudo chroot . bin/bash
chroot: failed to run command ¡®bin/bash¡¯: Exec format error
pi@raspberry4:~/rpi_mnt $ cd ~/rpi_mnt
pi@raspberry4:~/rpi_mnt $ ls -l
total 56
lrwxrwxrwx   1 root root     7 Apr 14 20:11 bin -> usr/bin
drwxr-xr-x   3 root root  3584 Jan  1  1970 boot
drwxr-xr-x   2 root root  4096 Apr 14 20:12 debootstrap
drwxr-xr-x  18 root root  4040 Apr 14 20:41 dev
drwxr-xr-x  27 root root  4096 Apr 14 20:12 etc
drwxr-xr-x   2 root root  4096 Feb  2 02:09 home
lrwxrwxrwx   1 root root     7 Apr 14 20:11 lib -> usr/lib
drwx------   2 root root 16384 Apr 14 19:59 lost+found
drwxr-xr-x   3 root root  4096 Apr 14 20:41 mnt
dr-xr-xr-x 195 root root     0 Jan  1  1970 proc
drwx------   2 root root  4096 Feb  2 02:09 root
drwxr-xr-x   2 root root  4096 Feb  2 02:09 run
lrwxrwxrwx   1 root root     8 Apr 14 20:11 sbin -> usr/sbin
dr-xr-xr-x  12 root root     0 Apr 14 19:56 sys
drwxrwxrwt   2 root root  4096 Feb  2 02:09 tmp
drwxr-xr-x   9 root root  4096 Apr 14 20:11 usr
drwxr-xr-x  11 root root  4096 Apr 14 20:11 var
pi@raspberry4:~/rpi_mnt $ root@raspberry4:
-bash: root@raspberry4:: command not found
pi@raspberry4:~/rpi_mnt $ ls -l
total 56
lrwxrwxrwx   1 root root     7 Apr 14 20:11 bin -> usr/bin
drwxr-xr-x   3 root root  3584 Jan  1  1970 boot
drwxr-xr-x   2 root root  4096 Apr 14 20:12 debootstrap
drwxr-xr-x  18 root root  4040 Apr 14 20:41 dev
drwxr-xr-x  27 root root  4096 Apr 14 20:12 etc
drwxr-xr-x   2 root root  4096 Feb  2 02:09 home
lrwxrwxrwx   1 root root     7 Apr 14 20:11 lib -> usr/lib
drwx------   2 root root 16384 Apr 14 19:59 lost+found
drwxr-xr-x   3 root root  4096 Apr 14 20:41 mnt
dr-xr-xr-x 196 root root     0 Jan  1  1970 proc
drwx------   2 root root  4096 Feb  2 02:09 root
drwxr-xr-x   2 root root  4096 Feb  2 02:09 run
lrwxrwxrwx   1 root root     8 Apr 14 20:11 sbin -> usr/sbin
dr-xr-xr-x  12 root root     0 Apr 14 19:56 sys
drwxrwxrwt   2 root root  4096 Feb  2 02:09 tmp
drwxr-xr-x   9 root root  4096 Apr 14 20:11 usr
drwxr-xr-x  11 root root  4096 Apr 14 20:11 var
pi@raspberry4:~/rpi_mnt $ root@raspberry4:echo 00:00:10
-bash: root@raspberry4:echo: command not found
pi@raspberry4:~/rpi_mnt $ date
Tue 14 Apr 2020 08:44:14 PM JST
pi@raspberry4:~/rpi_mnt $ root@raspberry4:
pi@raspberry4:~/rpi_mnt $ 
pi@raspberry4:~/rpi_mnt $ 
pi@raspberry4:~/rpi_mnt $ su - root
Password: 
root@raspberry4:~# 
root@raspberry4:~# 
root@raspberry4:~# compile finish
-bash: compile: command not found
root@raspberry4:~# exit
logout
pi@raspberry4:~/rpi_mnt $ cd 
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt/mnt/compile
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt/dev/pts
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt/proc
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt/sys
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt/dev
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt/boot
pi@raspberry4:~ $ sudo umount  ~/rpi_mnt
pi@raspberry4:~ $ sudo losetup -d  /dev/loop0
pi@raspberry4:~ $