I'm asking this question because I'm personally confused on how org-clock works in general.

My org-clock-save.el file only has one line,

;; org-persist.el - PCNAMEHERE at <2016-04-24 Sun 11:16>

From what I understand, the only thing the file is doing is telling emacs/org-mode to save my clock times across sessions. Furthermore, the only changes I see is that it updates the time stamp and the last computer that used it whenever it gets saved. Is this true?

That said, then where does org-mode save my clock times?

I use github to sync my .emacs.d file across two computers, so there are some files I put in my .gitignore files so that packages and other files get installed and set locally. Would it be safe to add my org-clock-save.el file to this now? For clarity, I've already pushed and pulled org-clock-save.el a few times between PCs, so there is a file on each pc saying this with the only difference being the time stamp between pulls/pushes.

1 Answer 1


The file org-save-clock.el is used to store two kinds of information:

  • the active clock if emacs is shut down while a task is active (gets stored in org-clock-stored-resume-clock)
  • the history of the n last clocked tasks (in a list of conses in org-clock-stored-history), where n is determined by the number stored in org-clock-history-length (default is 5)

Whether both of these variables are saved to the file depends on the setting of org-clock-persist. If you set it to t both informations are kept.

A short look at the source code in org-clock.el reveals that the org-save-clock.el file is read by the org-clock-load function. It checks whether the file belonging to the recorded task exists, and if yes, it prompts the user whether the clock shall be resumed.

Important: The active clock is only saved to org-clock-stored-resume-clock when emacs is shut down; this can be seen in org.el where the org-clock-save function is added to the kill-emacs-hook.

The contents of org-clock-stored-history are used in more places. But mostly it serves as a clock-in convenience when using the org-clock-select-task interactive function that lets you choose from the last few clocked tasks by using the tasks saved in that variable.

The information in the initial line of the org-clock-save.el file (the host and date information in the org-persist line) is not used at all inside the code. The file gets loaded as lisp code and there this line is just a comment.

Now, after all these facts, to your question: Is it safe to add org-clock-save.el to the .gitignore file?

If you want to be able and resume a clock on computer B that you clocked in to on computer A before shutting down emacs on A, then you would need to have it synced. Else you lose the information of the active clocked-in task.

But on the other hand, your loss is not big, because the more important state is always conserved in the tasks in the org files themselves, where for each clock interval you have a CLOCK line, and org will warn you if there is a dangling clock item.

Actually, I think git is anyhow not the best thing for syncing such state files. I think it is easier to keep these frequently changing state files on a dropbox-like service. Else your commit history fills up with a lot of trivial stuff. Git is good for the rest of the emacs.d directory to track the configuration changes. So, my personal choice would actually be to define the position of the org-clock-save.el file to be on a dropbox-like storage and take it out of the git repo (you could change the location by setting another path by redefining the org-clock-persist-file variable).

The whole clock saving mechanism naturally falls short if there are two open emacs sessions working at the same time with the org-clock-save.el file or also if you forget to sync. This can lead to minor conflicts (but that is trivially true for many use cases where files are synched but do not get locked). However, as already noted: The most important information is kept in the org files themselves (the CLOCK lines), so the information there is authoritative and overrides the state information in org-clock-save.el.

  • Do you know of a way to sync clocks without shutting down either Emacs instance? May 9, 2017 at 23:03

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