Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

When I double-click on a CSV file on a network share, the file is opened in Microsoft Excel (which is what I want). However, Excel assumes that I'm going to modify the file, and that everyone else is too, and so puts a lock on it.

In practice I very rarely actually want to modify these files, merely read from them. And if I have the file open in an Excel window in the background, it stops anyone else from opening the same file.

I am aware that I can manually open a file as read-only from the File -> Open dialog within Excel. However I almost always open files by double-clicking on them in Explorer (or Outlook, for attachments). Is it possible to change the file association so that the default handler for CSV files is "Excel in read-only mode"? Is there a command-line argument that I can use in the Open With... dialog to achieve this?

Or more bluntly - when I am looking at a CSV file in Windows Explorer, is there an easier way to open it read-only than starting up Excel myself, selecting File -> Open, choosing "read only" from the dropdown, manually navigating to the same folder in the hierarchy, and then opening the file?

(I am happy to have to jump through hoops on the rare occasions that I want to modify and save a file.)

share|improve this question
up vote 8 down vote accepted

I was able to reach a satisfactory conclusion to this by adding the following keys to my registry:

@="Open read-only in Excel"

@="\"C:\\Program Files (x86)\\Microsoft Office\\Office12\\EXCEL.EXE\" /r \"%1\""

These create an entry on the right-click shell menu in Windows Explorer called "Open read-only in Excel". When selected, this launches Excel with the /r flag (as per the command in the second key), which opens the file in read-only mode.

This is not perfect - I would rather that this were the default action for a CSV file, and that a context option was needed to launch in read-write mode. However it is a vast improvement on the situation before.

share|improve this answer
you are almost there - to now set that action as default, set the key [HKEY_CLASSES_ROOT\Excel.CSV\shell, value (Default) to Open_in_read_only_Excel – SeanC Oct 23 '12 at 14:39

If you have control over how the file is saved then you can have it saved with an option that prompts read-only access whenever it is opened.

File > SaveAs > Tools > General Options... > Read-only recommended

share|improve this answer
That doesn't appear to work with CSV files (which makes sense as they have nowhere to store metadata). Plus the files are created by an automated FTP fetch, so unless a Unix process could set this flag I don't think this approach will bear fruit. – Andrzej Doyle Oct 22 '12 at 10:36

Here's the equivalent of Andrzej Doyle's answer for Excel 2013, which uses DDE, and also sets "Open (read-only)" as the default action:

Windows Registry Editor Version 5.00


@="Open (read-only)"

@="\"C:\\Program Files\\Microsoft Office 15\\Root\\Office15\\EXCEL.EXE\" /dde"

@="[open(\"%1\" /ou \"%u\",,1)]"


(Yes, it's the ,,1 that makes the file read-only. How obscure!)

share|improve this answer
Just to clarify: The accepted method doesn't work anymore for Excel 2013? What exactly is DDE? (haven't googled it yet) – nixda Oct 16 '15 at 13:24
It still works if you update the Excel EXE path, but the default "Open" command for Excel 2013 uses DDE, so I thought I'd better stick with that to be safe. – EM0 Oct 16 '15 at 14:00
@nixda DDE is an old way of doing inter-process communication that is still well supported by several parts of MS Office. – Nameless One Jan 12 at 11:10

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.