simple Carbon + Cocoa command-line utility to set or retrieve the current Spaces workspace ID.
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Makefile Updated readme with new name, and a bit about how to install the binary Jun 24, 2011

Command-line OSX Spaces Manipulation Tool

Original code is by shabble, with some updates from canadaduane, animated switching code and dimension retrieval inspired by a blog post from Denis Gryzlov.

For a variety of useful and useless purposes when scripting in OSX, it might be handy to know which of the Spaces (virtual desktops) you're currently on. You may also wish to programmatically switch spaces from the command line.

Mac OSX Hints has one possible solution, which uses the Assistive Devices support to rip the value from the menubar icon, but this is really horribly hacky, and pretty slow, at least for me. It takes at least a second, and more like 2 or 3 typically.

An alternative idea is presented on StackOverflow which uses some Carbon API calls to fetch a window handle of the currently focused app (which is presumably on your current space), and then poke around in its internal metadata dictionary to find its workspace ID.

The latter is the method implemented here.

Binary Install

  1. Download the compiled binary
  2. Double-click to mount the image file
  3. Drag the spaces-util onto the Binaries Folder
  4. Enter your password if prompted (The Binaries Folder link points to your /usr/local/bin, which you may require Administrator rights to write to.
  5. After copying, eject the disk image, which can now be deleted.
  6. If you do not want to install the program globally, copy it to somewhere in your local $PATH.


Compile with:

$ make

and run with:

$ ./spaces-util [options]

or copy it to somewhere in your $PATH. There is currently no install target in the Makefile.

Usage & Options

If you have copied the program to a directory in your $PATH, you can invoke it with simply $ spaces-util [options]. Otherwise, you must navigate to the compile or copy directory, or invoke it with a full path.

  • -a animates space transition (only when -s is used)
  • -q quiet mode, prints a single number with the current space ID
  • -qq prints no output at all. Only useful with -r or -s
  • -r encodes the space ID in the process return value
  • -n returns the dimensions of the Spaces configuration
  • -s <num> sets the current space to <num>. Any 'fetch' configuring arguments are ignored when used in conjunction with -s

Fetching Spaces ID

The program should terminate immediately, printing a string to STDOUT which matches the regex /^Current Space ID: \d+$/. If you pass the -r option, the return value of the program is set to the current Space number for ease of use in scripting.

For example, in Bash: $ ./spaces-util -r -qq; echo $? will print the Space number apps. If the space cannot be determined for any reason, it will be returned as -1 (255).

If you call spaces-util with the -q option, it will enter quiet mode and only print the space number (matching /^\d+$/). The silent version (-qq) will print nothing to STDOUT, and any error messages will be printed to STDERR. Silent is generally only useful if you're switching Spaces, or planning to use the return value.

Fetching Spaces Dimensions

The -n flag returns one of two strings, depending on whether quiet mode is enabled. If quiet is enabled, it will print /^\dx\d$/, where each number is a single digit in the range 1 .. 4.

If quiet is not enabled, the output is more verbose: /^Spaces dimensions: \d rows, \d columns$/

In silent mode, nothing is printed at all.

The return value is the current Space number (if using -r), or 0 for success. It is set to -1 (255) for any failure.

Setting Spaces ID

spaces-util now supports switching to other Spaces via the -s option. Specifying -s <num> on its own will switch directly to that space, without any transitional animation. The -a (animate) flag enables the usual "slide" transition effect.

Quiet and silent mode can be used with with -s option, otherwise, it will print a message /^Switched to \d+/ to STDOUT, or an error message to STDERR if it fails.

The return value is NOT set to the Space number when using the set feature, it is either 0 (for successful operation), or -1 (generally represented as 255) on error.

Attempting to set the Space number beyond the number of spaces available will result in an error. Spaces are numbered from 1 (top-left), to N, where N is rows * columns of your Spaces setup.


I have no idea what happens if Spaces are disabled, or if you manage to invoke it from the Spaces Expose screen, or other weird edge cases. Submissions welcomed. It uses a couple of undocumented or private API calls, so there's no guarantee it'll work in future versions of OSX.

It's survived fairly rigorous use on Leopard (10.5.8), and the fetch functions apparently work on Snow Leopard too. The setting functions there are as-yet untested. If you find it works/doesn't work, please leave me a message or add something to the issues page so I can update this statement with better data.

Currently there's no binary available. If there's any interest, I can build a Universal Binary and add it here somewhere. Message me if you can't build it yourself.