sudo mkdir -p /mnt/runimg
pi@raspberry48:~ $ sudo mount --bind /media/netdir/raspbrreyPi/mnt_runimg    /mnt/runimg
pi@raspberry48:~ $ ls -l /mnt/runimg/
total 18797568
-rwxrwxrwx+ 1               99   99 4555014144 Jan  7 22:32 2019-04-08-raspbian-stretch_chroot.img
-rwxrwxrwx+ 1 systemd-timesync   98 3481272320 Feb  9 23:45 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
drwxrwxrwx+ 1 root             root        160 Dec 19 22:41 bak
-rw-rw-rw-+ 1               99   99 1728053248 Feb 10 20:28 readynas_compile_tool2.img
-rw-rw-rw-+ 1               99   99 2173698048 Jan  8 23:25 readynas_compile_tool.img
pi@raspberry48:~ $ sudo mkdir -p ~/rpi_mnt
pi@raspberry48:~ $ sudo losetup -f -P --show /mnt/runimg/readynas_compile_tool2.img
/dev/loop0
pi@raspberry48:~ $ sudo mount /dev/loop0p2 -o rw ~/rpi_mnt
pi@raspberry48:~ $ cd ~/rpi_mnt
pi@raspberry48:~/rpi_mnt $ sudo mount --bind /dev ~/rpi_mnt/dev/
pi@raspberry48:~/rpi_mnt $ sudo mount --bind /sys ~/rpi_mnt/sys/
pi@raspberry48:~/rpi_mnt $ sudo mount --bind /proc ~/rpi_mnt/proc/
pi@raspberry48:~/rpi_mnt $ sudo mount --bind /dev/pts ~/rpi_mnt/dev/pts
pi@raspberry48:~/rpi_mnt $ sudo mkdir -p  /media/netdir/source/raspberrypi/4-02_readynas
pi@raspberry48:~/rpi_mnt $ sudo mkdir -p  ~/rpi_mnt/mnt/compile
pi@raspberry48:~/rpi_mnt $ sudo mount  --bind  /media/netdir/source/raspberrypi/4-02_readynas ~/rpi_mnt/mnt/compile
pi@raspberry48:~/rpi_mnt $ cd ~/rpi_mnt
pi@raspberry48:~/rpi_mnt $ sudo chroot . bin/bash
root@raspberry48:/# 
root@raspberry48:/# ls -l
total 76
drwxr-xr-x   2 root root  4096 Jan 13 02:37 bin
drwxr-xr-x   2 root root  4096 Jun 17  2018 boot
drwxr-xr-x  17 root root  3960 Feb 28 13:23 dev
drwxr-xr-x  66 root root  4096 Jan 13 00:46 etc
drwxr-xr-x   2 root root  4096 Jun 17  2018 home
drwxr-xr-x  12 root root  4096 Jan 13 02:37 lib
drwx------   2 root root 16384 Jan 12 13:37 lost+found
drwxr-xr-x   2 root root  4096 Jan 13 02:37 media
drwxr-xr-x   3 root root  4096 Jan 13 02:37 mnt
drwxr-xr-x   2 root root  4096 Jan 13 02:37 opt
dr-xr-xr-x 180 root root     0 Jan  1  1970 proc
drwx------   2 root root  4096 Jan 12 14:00 root
drwxr-xr-x   4 root root  4096 Jan 12 13:43 run
drwxr-xr-x   2 root root  4096 Jan 12 13:43 sbin
drwxr-xr-x   2 root root  4096 Jan 13 02:37 srv
dr-xr-xr-x  12 root root     0 Jan  1  1970 sys
drwxrwxrwt   2 root root  4096 Feb 10 11:27 tmp
drwxr-xr-x  10 root root  4096 Jan 13 02:37 usr
drwxr-xr-x  11 root root  4096 Jan 13 02:37 var
root@raspberry48:/# echo 00:00:00
00:00:00
root@raspberry48:/# date
Fri Feb 28 13:23:04 UTC 2020
root@raspberry48:/# cat /usr/bin/gcc
#!/bin/bash
gcc-4.9 $* -mcpu=cortex-a7

root@raspberry48:/# cat /usr/bin/g++
#!/bin/bash
g++-4.9 $* -mcpu=cortex-a7

root@raspberry48:/# compile i         
root@raspberry48:/# compile finish
bash: compile: command not found
root@raspberry48:/# exit
exit
pi@raspberry48:~/rpi_mnt $ cd 
pi@raspberry48:~ $ sudo umount  ~/rpi_mnt/mnt/compile
pi@raspberry48:~ $ sudo umount  ~/rpi_mnt/dev/pts
pi@raspberry48:~ $ sudo umount  ~/rpi_mnt/proc
pi@raspberry48:~ $ sudo umount  ~/rpi_mnt/sys
pi@raspberry48:~ $ sudo umount  ~/rpi_mnt/dev
pi@raspberry48:~ $ sudo umount  ~/rpi_mnt
pi@raspberry48:~ $ sudo losetup -d  /dev/loop0
pi@raspberry48:~ $