It's not quite as "deep" as Cygwin.
It doesn't allow access to the lowest level (/dev/sda).
When you run the Bash shell, you can
cd /mnt/C
and all the Windows drive letters are under the /mnt point.
/mnt/C , /mnt/D , /mnt/E ...
ls
pagefile.sys
hiberfil.sys
...
Bash shell uses "ls" instead of "dir".
You can install packages.
apt install disktype
If you type the name of a utility that is not installed
disktype
the shell will print out a one-liner telling you how to get it.
That's why I don't have to worry about the exact syntax. It'll
tell you. You put sudo in front of the command, to run it
with root privileges.
sudo apt install disktype
You can tell "who" you are, account wise, with
whoami
which Windows also supports now :-)
There is no XWindows (Xorg). You cannot run the Linux Firefox, *unless*
you arrange some sort of X solution. You can use a Windows Xorg,
as a replacement (XMing). So you could run Firefox from the Linux side.
Start XMing first. Set the Display environment variable in your
Bash shell. Then launch Firefox.
https://en.wikipedia.org/wiki/Xming
You could use
xdpyinfo
to find out what "extensions" your Xming supports after you've
started it, and then work out whether Firefox needs something
that isn't present in the X you're using. That's one of the
shortcomings of "bodging" a graphics subsystem onto the Bash
shell, is the Windows freebies, don't have nearly as many
extensions compiled in, as the one native to Linux. That's not
to say it can't be done - if you're paying someone for the
program, chances are it would be more complete (there are
commercial packages - I think I have one sitting around
somewhere here).
And it's bound to have some subsystem limitations. If it
doesn't admit to having /dev/sda, then there are going to
be a few things that won't work. It's supposed to be
a scripting environment, not a full copy of a Linux Distro.
I had a gawk script that was causing my gnuwin32 copy of
Gawk.exe to crash (I've only had that thing crash the one time).
And the first usage I made of the Bash shell, was to run the
Linux Gawk 4, which ran at exactly the same speed as my other
one, but didn't crash :-) Not crashing makes a big difference
to your productivity. It was a happy coincidence that the
one time gawk.exe crashed on me, that Bash shell was sitting there
waiting for a test case.
But other people, like to try "bar bet" test cases on it.
Like getting Linux Firefox running on it, a day or two after the
Win10 Bash beta was released.
Paul