I know this has been written a few time online, but the last time I needed to read up on it, it took a little long to find the answer.
What I wanted to do was to chroot in to a new root, then exit that chroot via python .
Below we have my current working directory that is /root , take a look at what we have in the directory:
In [1]: import os
In [2]: os.system('pwd')
/root
Out[2]: 0
In [3]: os.system('ls -l /root')
total 12
drwxr-xr-x 3 root root 4096 Dec 5 15:47 filesystems
drwxr-xr-x 3 root root 4096 Dec 5 15:01 iso
drwxr-xr-x 3 root root 4096 Dec 5 15:14 squashfs
Out[3]: 0
I’m then going to keep track of my current root, this part is very important:
In [4]: real_root = os.open('/', os.O_RDONLY)
And change to a new root, I’m going to use a archlinux squashfs I had laying around:
In [5]: os.chroot('/root/squashfs/archlinux/')
In [6]: os.chdir('/root')
We are now in the new room, lets have a look around:
In [7]: os.system('pwd')
/root
Out[7]: 0
In [8]: os.system('ls -l /root/')
total 16
-rw-r--r-- 1 root root 7725 Dec 5 21:12 install.txt
And lets go ahead and back out of this chroot back up to the real root filesystem:
In [9]: os.fchdir(real_root)
In [10]: os.chroot('.')
In [11]: os.chdir('/root')
And lets verify our old data is in place:
In [12]: os.system('pwd')
/root
Out[12]: 0
In [13]: os.system('ls -l /root/')
total 12
drwxr-xr-x 3 root root 4096 Dec 5 15:47 filesystems
drwxr-xr-x 3 root root 4096 Dec 5 15:01 iso
drwxr-xr-x 3 root root 4096 Dec 5 15:14 squashfs