Why can't the execution program be found in emacs?

I remember a friend asked me some time ago why I couldn't open the matlab program in emacs? It can be opened in terminal but not in emacs.

Today, I finally encountered a similar problem. After installing racket 6. 0. After installing racket, the execution path of the racket program is/usr/local/racket/bin.

Then I added this PATH to the PATH, which can be opened in the terminal environment.

Next, install Geiser. It is a plug-in connecting to racket in emacs. It is easy to install. I put the compiled file ~ /. Emacs. d/site-lisp/geiser

Then add the following lines in init. el. For my preparation files, see https://github.com/aborn/ulitcs

(load "~/.emacs.d/site-lisp/geiser/elisp/geiser-load")

Then M-x run-geiser was used to find that the racket program could not be found. At this time, I was thinking that the PATH in the bash environment should not be used in emacs,

Otherwise, why can't I find it?

The two links link1 and link2 are found online, and the execution path of emacs is determined by the exec-path variable.

Open M-x ielm to view the exec-path and find the following content:

exec-path("/usr/local/sbin" "/usr/local/bin" "/usr/sbin" "/usr/bin" "/sbin" "/bin" "/usr/games" "/usr/local/games" "/usr/lib/emacs/24.3/i686-linux-gnu")

No/usr/local/racket/bin found

In this case, you only need to add the following lines to the preparation file init. el and add the path/usr/local/racket/bin to exec-path.

(add-to-list 'exec-path "/usr/local/racket/bin")

Check exec-path.

ELISP> exec-path("/usr/local/racket/bin" "/usr/local/sbin" "/usr/local/bin" "/usr/sbin" "/usr/bin" "/sbin" "/bin" "/usr/games" "/usr/local/games" "/usr/lib/emacs/24.3/i686-linux-gnu")

Then execute M-x run-geiser.

My operating system is Ubuntu 14.04 LTS