Re: What's the differences b/t M-x eshell and M-x shell.

[Xah Lee]

eshell is written entirely in elisp.

practically speaking, that means when you are on Windows and don't
want to deal with cygwin or whatnot extra, you have eshell with almost
all the unix ls, cat, stuff.

• 〈Emacs Shell Tutorial (bash, cmd.exe, PowerShell)〉
http://xahlee.org/emacs/emacs_unix.html

you can get and set environment variables within emacs by:

; show env var named path
(getenv "PATH")

; example of setting env var named “path”
; by appending a new path to existing path
(setenv "PATH"
  (concat
   "C:\\cygwin\\usr\\local\\bin" ";"
   "C:\\cygwin\\usr\\bin" ";"
   "C:\\cygwin\\bin" ";"
   (getenv "PATH")
  )
)

detail at:

• 〈Emacs and Microsoft Windows Tips〉
http://xahlee.org/emacs/emacs_mswin.html

 Xah ∑ xahlee.org ☄