This is one of those totally basic operations that is right in your face with Firefox (“download file, or open with application ‘blah’ “), but with Safari it’s a battle with MIME types, “Universal” Type Identifiers, and file extensions. For the quick fix, copy com.apple.DownloadAssessment.plist into ~/Library/Preferences in your home directory and add to the list of file extensions that you want automatically opened after download (aka “Safe Files”).

I thought it would be straightforward to write a CGI script that emits CSV and have that automatically be opened in Excel. Good lord, what a pain. First of all, Safari has no easy way to associate a MIME type with an application. But can associate an application with a given file extension by doing a “Get Info” on the file in Finder … look for “Open with:”.

So I had to find and download a helpful app called RCDefaultApp. It installs as a System Preference and allows you to change all the crazy Launch Services business (associations MIME types, UTIs, file extensions, etc).

The official MIME types for CSV are text/csv and text/comma-separated-values. Unfortunately Safar breaks this. As far as I can tell, Safari just automatically displays “text/*” inline in the browser. So I used RCDefaultApp to defined “application/csv” (yeah, I guess I should have made that “application/x-csv”), and associated that with Excel.

Here is the perl code I used to test this whole mess:

#!/usr/bin/perl -w
 
$result = "foo,bar,baz\n";
 
print "Content-type: application/csv\n\n$result";

And here is the plist file just to give an idea of what it looks like:

LSRiskCategorySafe
 
LSRiskCategoryExtensions
 
csv

Figuring out how to tell Safari that CSV was a “Safe File” was harder to track down. It’s totally undocumented, but a couple of hardy Mac OS X nerds have uncovered the fact that com.apple.DownloadAssessment.plist holds the key to the magic. It allows you to override the download assessments that are hard coded into Launch Services. A post over at MacEnterprise.org provides some great documentation on exactly how to set this up.

The asute reader will notice that my com.apple.DownloadAssessment.plist file has a definition for the “csv” file extension rather than a MIME type. That’s because to get things to work at all, I had to actually make my CGI script have a filename that ends in “.csv”, which is totally crazy. Otherwise Safari downloads the file alright, but it saves it with a file extension of “.pl” or “.cgi”, and then cleverly reminds us that we might be downloading a PERL executable. In fact it is simply CSV text with a “.pl” extension. So it looks like the key steps here were:

• renaming CGI script to so it downloads with the proper “csv” file extension
• use Finder to make “csv” files open with Excel
• construct and install a com.apple.DownloadAssessment.plist so Safari will automatically open the “csv” file after download.

Gosh, Mac’s are so easy to use, I can just hardly believe it :-) Sorry folks, I think this is a case where the “PC guy” wins, hands down.

Link to Modifying Safari Safe Files List
Link to RCDefaultApp for editing MIME type associations

Filed under: apps, osx · 1 Comment