where does Emacs source the shell configuration files from?

[Sivaram Neelakantan]

on GNU Emacs 29.4 (build 2, x86_64-w64-mingw32) of 2024-07-05, when I
invoke M-x shell, I get garbled characters which seem to go away with
with setting PS1; see below

--8<---------------cut here---------------start------------->8---
bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell
]0;/c/gnu/emacs-29.4/bin
agam@agamam  /c/gnu/emacs-29.4/bin
$ echo $PS1
\[\e]0;\w\a\]\n\[\e[32m\]\u@\h \[\e[35m\]$MSYSTEM\[\e[0m\] 
\[\e[33m\]\w\[\e[0m\]\n\$
]0;/c/gnu/emacs-29.4/bin
agam@agamam  /c/gnu/emacs-29.4/bin
$ export PS1="\e[0;31m[\u@\h \W]\$ \e[m "
[agam@agamam bin]$  pwd
/c/gnu/emacs-29.4/bin
[agam@agamam bin]$
--8<---------------cut here---------------end--------------->8---

So, I try to plug in the above PS1 in different places and it doesn't to
seem to get read at all.  I've tried ~/.bashrc   which points to
c:/Users/agam/AppData/Roaming and ~/.emacs_bash in the same place. I've
also tried .bashrc in mys home directory but it doesn't be seem be read

--8<---------------cut here---------------start------------->8---

    (setenv "BASH_ENV" "~/.bashrc")
    (setq explicit-shell-file-name "C:/msys64/usr/bin/bash.exe") 
    (setq shell-file-name          "C:/msys64/usr/bin/bash.exe")
    (setenv "SHELL" shell-file-name)
    (setq shell-command-switch "-ic")
    (add-hook 'comint-output-filter-functions 'comint-strip-ctrl-m)
    (autoload 'ansi-color-for-comint-mode-on "ansi-color" nil t)
    (add-hook 'shell-mode-hook 'ansi-color-for-comint-mode-on)
--8<---------------cut here---------------end--------------->8---

What am I doing incorrectly?  And where should the PS1 be plugged in?
And is there a way to see which config files are being sourced when M-x
shell is invoked?

sivaram
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