Introducing appmodmap: make the Command key work again (or, making Mac refugees into Talos owners)

At least in terms of sheer numbers, Power Macintoshes are still the most common Power ISA-based computers, and those of us who still used Power Macs until lately (while my trusty 13-year-old Quad G5 may no longer be my daily driver, it is still used, and it's still under my desk) may well be the Talos II's most natural audience: we gravitate to non-x86 architectures, we like PowerPC in particular, and many Power Macs nowadays run Linux too. Yes, of course there are other audiences for the T2 and it's the truly open libre nature of the architecture that's its strongest general selling point, but those folks attracted by "the next Power Mac" are going to come from the Apple world and it would be nice to help them feel more at home. Yes, the T2 has a unique advantage in that Mac OS X can be run under QEMU with KVM acceleration. But even virtualization has a speed penalty and doesn't always work, and native apps will be more current.

The screenshot at right shows GNOME OSC overlaid with my own tweaked GNOME shell theme, unmistakably still GNOME but evocative enough of early Mac OS X to make me feel at home. Having used Macs in some way or another since 1987, and still using a MacBook Air as my travel laptop (at least until 10.15 makes it impossible to run 32-bit apps, which is where I'll be getting off the fruit bus, thank you), the look isn't jarring switching back and forth and my friend Jon thought I was still on the G5 after a cursory glance at the screen.

However, the other deeply wired part of Mac users is the Command key. My muscle memory is incredibly ingrained with Command key combinations after all these years. I always feel a little hobbled on a regular PC keyboard, and since my KVM is shared between the Quad G5, the Talos II, an SGI Fuel and a Mirrored Drive Doors Power Mac G4 and I use an old-school white Mac keyboard for all of them, having to internally codeswitch back and forth from Ctrl-Q to Cmd-Q may be a first world problem but sure gets obnoxious after awhile. The tips in this article are by no means specific to the Talos systems, but speaking from my own experience I suggest they might make things a bit less alien for a Mac user in transition.

Naturally, by default most things use Control key combinations. Some users will just switch Control and Command but I find this a rather blunt solution that works for some apps but not others. GNOME's system software is somewhat more accommodating to Command key users than KDE, but at the application level rather few packages, GNOME, KDE or otherwise, will let you change their built-in keymappings. Even of those that do, it doesn't always work, or they don't allow the use of the "Super" (their alias) key except in certain specific situations. Fortunately GNOME Terminal does allow this, so I manually remapped my usual keystrokes to the standard Mac combinations. On the browser side, if you go into about:config in Firefox and set ui.key.accelKey to 91 (and possibly restart the browser and/or reset your profile), it will generally work there also mostly as you expect and menus will show the equivalent combinations with the "Win" key instead. This isn't a perfect solution since sometimes the keybindings don't stick in odd places, or some sites will sniff Linux from your user agent string and enforce Control key combinations (Blogger, ahem), but it largely works out of the box.

Unfortunately such applications are the exception and not the rule. Changing GNOME's keyboard settings to map Close Window to Super-Q (Command-Q) will at least make most other apps close in a Mac-like fashion but there isn't much otherwise for any of the other typical functions.

The usual advice people suggest is something like AutoKey. In fact, I did use AutoKey myself for awhile and I can't complain about the functionality it offers, but I found it rather fragile and prone to crashes during use and after a couple system updates it then stopped working completely. More to the point, it was labourious drudgery to manually reconstruct all the Command key combinations for the apps that needed them, and I never ended up finishing that work before it finally crapped out.

Really, all we need is just a way to dynamically determine which app is up and then transparently swap keys around as required based on it. As usual, if you want something done you do it yourself. The result is appmodmap.

appmodmap is a small daemon that watches what the topmost X11 window is and dispatches scripts to change system settings as required. I wrote it for the Talos and I haven't tested it on anything but Fedora, but it strictly uses documented calls and thus should work on anything with X11 and POSIX. It doesn't need elevated privileges and can simply run as you. As compiled out of the box (see the README), it uses setxkbmap and gsettings to alias the Control key to the Command key for the apps on my machine that need it and still provide things such as Super-Tab to switch applications regardless of whatever app is frontmost. When the remapping isn't required for an application, appmodmap will quietly switch everything back to the default, and thus most things "just work." Note that in this scheme already existing Super-key combinations may get temporarily waxed while Control-key aliasing is still in effect, so I had to change a few more shortcuts I need in GNOME's keyboard settings for things like taking screenshots (I remapped them to Alt/Option instead).

You can also use appmodmap as a general way to change any system setting dynamically based on the window class (just write the necessary primitives), but this was what I wrote it for originally, and I still include it as a useful demonstration. Best of all, rather than doing lots of hand work in the AutoKey interface, adding more applications to the daemon just means adding the window class hint name with the desired bitmask, then quickly rebuilding the daemon and restarting it.

Overall, speaking as a long-time Mac user, just a few tweaks made my T2 feel much more like I was used to and thus a lot more productive than having to untrain my fingers. If your primary interest is the Talos' strong commitment to freedom, you'll find a way to use it no matter what contortions the interface makes you do, but if you're a Power Mac user who's a little scared of Linux but yet needs more grunt than your trusty G-series Mac can muster, here's one less excuse for not moving on from the company that left you high and dry.


  1. I'm one of the refugees. I thought about a switch to Linux long time ago. I have installed Debian on the last PowerBook G4. I bought now the Blackbird Quadcore Bundle and will make then the final switch from MacOS X to Linux or BSD.


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