Can Finder and the "open" command treat files with .sh or other typical extensions just like .command files?

I am looking for a way to inject some more extensions into the OS X launch services database systematically so that when clicked, they execute in the terminal app just like .command files do by default.

Things like .ksh, .sh, and .csh would be nice to start, but I assume once I figure out how to add one, it's easy to do the rest.

An answer specific to Lion or Snow Leopard is fine, so a general-case answer for all OS versions is not necessary. It would be great if this were scriptable and wrote directly to the Launch Services database so I could automate this rather than going to finder on each mac and doing a lot of clicking.

If a file is opened with Terminal, and has the execute bit set, then Terminal will execute it.

Get Info on a .sh file and set it to be opened with Terminal, and click the Change All button.

To prefer Terminal to open .sh files — using the defaults command, without using Finder

In most cases, all that's required should be possible from the command line …

Preparation

Two commands:

defaults read com.apple.LaunchServices | grep -B 1 -A 3 public.shell-script

defaults read com.apple.LaunchServices | grep -B 1 -A 4 "LSHandlerContentTag = sh;"

If either command reveals an existing preference

Use Xcode or any other suitable property list editor to remove the relevant dictionary from the LSHandlers key within the following file:

~/Library/Preferences/com.apple.LaunchServices.plist

Hints:

• defaults, with which I'm more familiar, seems unsuitable for removal of a single dictionary from an array
• removal should be necessary only if (say) the user has previously used Finder to associate .sh files with an application other than the system default
• a Super User answer under How to change default app for all files of particular file type through terminal in OS X? is recently edited to include a script that uses PlistBuddy — credit to Daniel Beck.

Adding to LaunchServices preferences, for Terminal to view and edit .sh files

Two one-line commands.

Depending on your requirements, the first command alone may suffice:

defaults write com.apple.LaunchServices LSHandlers -array-add '{ LSHandlerContentType = "public.shell-script"; LSHandlerRoleViewer = "com.apple.Terminal"; LSHandlerRoleEditor = "com.apple.Terminal"; }'

defaults write com.apple.LaunchServices LSHandlers -array-add '{ LSHandlerContentTag = "sh"; LSHandlerContentTagClass = "public.filename-extension"; LSHandlerRoleViewer = "com.apple.Terminal"; LSHandlerRoleEditor = "com.apple.Terminal"; }'

For the new preferences to be respected

Modifications to the user domain persistence layer of Launch Services must be acknowledged. For this, least disruptive to the end user will be:

• a restart of the operating system.

From the command line, if immediate restart is acceptable:

sudo shutdown -r now

Background

Understanding Terminal.app support for .sh (public.shell-script)

Consider the result of the following command:

defaults read /Applications/Utilities/Terminal.app/Contents/Info

• under CFBundleDocumentTypes (an array of dictionaries describing the document types supported by the bundle) we see that Terminal is designed to support com.apple.terminal.shell-script

• public.shell-script (the system-declared UTI associated with .sh) is not supported at that level, it appears elsewhere in the property list — under UTExportedTypeDeclarations

Terminal aside for a moment: it's sometimes inappropriate (or simply worthless) to force opening of a document type, by an app that is designed without support for that type.

For Terminal, I imagine no harm in handling the public.shell-script type.