问题
When I start emacs I get the error
Debugger entered--Lisp error: (wrong-type-argument stringp nil)
string-match("cmd\\.exe" nil)
(if (string-match "cmd\\.exe" tramp-encoding-shell) "/c" "-c")
eval((if (string-match "cmd\\.exe" tramp-encoding-shell) "/c" "-c"))
this appears to occur when loading the magit pack
eval-buffer(#<buffer *load*-330059> nil "c:/cygwin64/home/johnstonk/.emacs.d/emacs-live/packs/stable/git-pack/lib/magit/magit.el" nil t) ; Reading at buffer position 3100
I confirmed this occurs with a fresh git clone of emacs-live. I tried removing the magit pack from loading in the live init file but I got the same error again when it loaded the clojure pack. Looks like a nil string error in tramp.
Does anyone know why?
回答1:
Going through and loading the source code for tramp-sh.el I got the same (wrong-type-argument stringp nil) on the first line (require 'tramp)
So I loaded tramp.el (version 22.1) and got to the section
(defcustom tramp-encoding-shell
(if (memq system-type '(windows-nt))
(getenv "COMSPEC")...
I noticed that this system-type is getting set to windows-nt (As it should, I'm on windows7) but (getenv "COMSPEC") is returning nil. From what I googled elsewhere this COMSPEC environment variable is expected to exist on windows machines and point to the shell. Tramp uses the tramp-encoding-shell var for encoding and decoding commands on the local machine such as "~" -- at least according to tramps comments.
COMSPEC didn't exist as an system environment variable for me so I created it and pointed it to cmd.exe C:\Windows\System32\cmd.exe That fixed it for me.
Note don't set COMSPEC to powershell, I tried that first but got a nasty memory leak when I tried to use lein (keeps trying to create a server, fails, and tries again but doesn't clean up previous thread).
来源：https://stackoverflow.com/questions/29477035/error-when-loading-emacs-with-emacs-live