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Due to emacs interlocking files I want to run org-mobile command via cron but using the emacsclient:

emacsclient -nw --eval "(org-mobile-pull)" --eval "(org-mobile-push)"

but if there is no emacs server running I want the command to run using emacs batch mode:

emacs --batch --eval "(org-mobile-pull)" --eval "(org-mobile-push)"

I'm not sure how to accomplish this so curious if anyone has any ideas.

J Spen
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2 Answers2

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I'm curious what you're ultimately trying to accomplish? Why not just always start a new Emacs process? The additional overhead would be a small fraction of a second

On my 2 year old MBP:

% time emacs --batch --eval nil emacs --batch --eval nil 0.03s user 0.01s system 87% cpu 0.054 total

Going down your current path, you can check the exit code from emacsclient to decide if you should run in batch

if emacsclient --eval nil >/dev/null 2>&1; then echo "run client"; else echo "run emacs"; fi

EDIT: I see you want to script an answer to the lock stealing question. Check out my answer to this question for using ask-user-about-lock to solve this.

EDIT: So the idea is to redefine ask-user-about-lock to return t. See docs:

ask-user-about-lock is an autoloaded Lisp function in `userlock.el'.

(ask-user-about-lock FILE OPPONENT)

Ask user what to do when he wants to edit FILE but it is locked by OPPONENT. This function has a choice of three things to do: do (signal 'file-locked (list FILE OPPONENT)) to refrain from editing the file return t (grab the lock on the file) return nil (edit the file even though it is locked). You can redefine this function to choose among those three alternatives in any way you like.

[back]

script example (remember to chmod)

#!/usr/bin/env emacs --script

(defun ask-user-about-lock (file opponent)
  t)

(org-mobile-pull)
(org-mobile-push)
Community
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event_jr
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  • Of course, if you're *really* out of luck one day, the server will terminate right between the `if` and the `then`... ;-) – Thomas Jul 15 '12 at 07:13
  • @Thomas - The main issue is emacs locks the files so running emacs --batch gets the question of whether to steal, proceed, etc... and in batch mode this won't run if I have an emacs already open because the files are locked! If emacs is open, I would want to run the emacsclient. Also I was worried because I don't want the process sitting there waiting because it's waiting for s,q,p input. I thought cron set input to < /dev/null but this doesn't seem to stop the script when I run it from the terminal. Otherwise I might be fine with the script only running when emacs isn't open. – J Spen Jul 15 '12 at 08:55
  • @event_jr - Then terminating in all other cases. – J Spen Jul 15 '12 at 09:14
  • @JSpen see my edit for how to solve the lock stealing question. – event_jr Jul 15 '12 at 12:34
  • @event_jr - I assume I would then just need to run the emacs batch script but how do I integrate the function my-set-buffer-modified-p. Sorry I was a little confused from reading the link on how exactly to force it to send an answer to the lock question while running in batch mode. – J Spen Jul 15 '12 at 12:48
  • @event_jr - Got it working but ended up using emacs --batch and placing the defun in an eval statement. For some reason couldn't get the script to load my .emacs file. Was just loading the system file. – J Spen Jul 17 '12 at 09:11
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The emacsclient returns an error code if the server is not running. If you are certain that the code you want to eval will make emacsclient exit normally, then the following should work:

emacsclient -nw --eval "(org-mobile-pull)" --eval "(org-mobile-push)" 2>/dev/null || emacs --batch --eval "(org-mobile-pull)" --eval "(org-mobile-push)"

Note however that this simple approach discards potential error messages you might be interested in (but only in the case where emacsclient is run).

Thomas
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  • Note that the code would always run twice if an error is encountered. – event_jr Jul 15 '12 at 07:06
  • @event_jr: Exactly, hence this should only be used if you are certain that emacsclient will exit normally whenever the server is running. – Thomas Jul 15 '12 at 07:11