This will create a file called foo.r which is the decompiled resource fork as a text file. Then, pull out the resource fork with DeRez, like this (assuming a file foo.txt, and that the application you want to use is Firefox.app). This creates the resource fork in the file - if you don't do this, there'll be no information to copy out. To change the association of a single file from the command line, first create a file of the right type, and manually change its association to the application you want it to open in. In particular, you can push a resource fork into a file with Rez. Apple provides two utilities, called 'Rez' and 'DeRez' with the developer tools, which allow you to manipulate resource forks. Picking up from Daniel Beck's answer above, this information is indeed stored in the file's resource fork. So you just need to create one 'template' file from an existing resource fork (in this example openInSublime2rsrc), and you can copy it to your other files afterwards. namedfork/rsrc is how the resource fork is exposed to POSIX applications (i.e.

$ open otherfile.txt # opens in Sublime 2 How can I open a script file with TextWrangler from the Terminal. I prefer to edit text files using TextWrangler. $ cp openInSublime2rsrc otherfile.txt/.namedfork/rsrc Often when I work in the Terminal (the command line) I need to edit einigen text files. $ cp somefile.txt/.namedfork/rsrc openInSublime2rsrc For example: $ open somefile.txt # opens in Sublime 2

# setting non-default application using Finder rw-r-r- 1 danielbeck staff 0 18 Mär 19:00 somefile.txt If this doesnt work you have to install the TextWrangler command line tools.

These resource forks are exposed as extended attributes ( Wikipedia): $ ls somefile.txt This information is stored in the file's resource fork ( Wikipedia).

Textwrangler command line tools