Eee 701 Planetoid


Quick tip: invert colours on a Linux X11 display

Filed under: Linux, Software — Tags: , , , — Tim @ 17:33

One feature I have set up (and find very useful) on my iPhone, is a triple-press on the “home” button to invert the colours on the screen. (I won’t go into details on how to do this in iOS—it’s not the purpose of this post—but basically, look in Settings > General > Accessibility for details.) This is really handy for moments when you just don’t want to look at a very white screen (and unfortunately, iOS7 has lots of those), and a triple-press will turn white to black, to spare one’s eyes, blushes, etc…

I wondered if there was a not-too-complex way to set up a similar feature on a Linux machine, preferably at the X11 level (i.e. not tied into a particular window manager or desktop environment), and a quick Google search revealed I was in luck.

In short, there’s an command-line utility called xcalib, which is mainly intended for monitor calibration, but which has a handy feature: yes, it can invert the current X display’s colours (effectively, giving you a negative of the display). The program isn’t included in Arch Linux’s main package repositories, so you’ll have to build/install xcalib from the AUR—it’s a tiny program, so that will barely take you longer than installing it from a repo would.

Once the program is installed, running

xcalib -i -a

(for “invert” and “action”—i.e. “do it”) will invert your display’s colours; running the same again will switch it back.

Very useful, and even more so if you assign it to a keyboard shortcut—each DE and WM has its own way of setting this up, but in Xfce you do this in Xfce menu > Applications > Settings > Keyboard > Application Shortcuts [tab]. I used Ctrl-Alt-I (for “invert”), but that’s just personal taste 🙂

Maybe this feature is already present in some DEs, but at least this one will work in any environment—hope it helps you too!



Quick Ubuntu tip: Better screensaver config options

Filed under: Linux, Software — Tags: , , , — Tim @ 21:43
XScreensaver preferences window

XScreensaver preferences window

Ever wondered why the screensaver settings in Ubuntu Linux (and derivatives like my Eee 701’s Eeebuntu) seem rather limited? Would you prefer to have a greater choice of setup options—e.g. automatic randomisation of screensavers, and configuration of individual modules—as you can see in the screenshot here?

It is fairly well-known that xscreensaver is the basis for Ubuntu’s screensaver facility, and also that the GNOME desktop environment uses its own configuration utility—gnome-screensaver—rather than xscreensaver’s own. (xscreensaver‘s creator Jamie Zawinski is, frankly and probably justifiably, quite scathing about this change.)

Fortunately, all is not lost. To get the full range of screensaver config options:

  1. Use your preferred package manager to remove gnome-screensaver and install xscreensaver.
  2. From the GNOME desktop, go to System > Preferences > Startup Applications.
  3. Choose the “Add…” option. In the “Name” field, add xscreensaver, and in the “Command” field, insert the text xscreensaver -nosplash. Select “OK”.

Now, when you access the screensaver options, you should have the full range of settings that xscreensaver has to offer. I found this worked for me, but you may wish to do your own research before trying it yourself—I take no responsibility if anything goes awry!

(I take no credit for discovering this tip, having found it on the Web somewhere, though I forget exactly where. Hope it helps someone, anyway 🙂 )


Two quick tips for KeePassX

Filed under: Software — Tags: , , , , — Tim @ 18:31

If I were writing my post “Ten programs I want on all my computers: the Eee 701 view” today (and I might still do an update sometime), I would definitely include one application which wasn’t present in the list at that time: KeePassX, the cross-platform encrypted password manager. (Actually, I did mention it in passing in the article, but I was still getting familiar with the program at the time.)

To cut a long story short: since I posted the above article, KeePassX has become one of those apps for me—you know, the programs you wonder how you ever did without. Basically, KeePassX—and its Windows cousin Keepass Password Safe—is a password manager for Linux and Mac OS X, which stores your login details for all those Web sites you visit, in a 256-bit-encrypted database file.

I could write a much longer article about why I think this is such a great app, but at this point I just want to share two tips for KeePassX which I have learned, and which I find very useful.

  • KeePassX uses the same database file format across platforms (I assume the Windows version does; certainly, Linux and Mac do), and you can customise the app’s settings to point to wherever the file is located.
    If you use Dropbox (and I can hardly imagine my Eee 701 without it 🙂 ), you can place the KeePassX database anywhere within your Dropbox folder, and the file will be synchronised across all your computers, thus ensuring you have an up-to-date password database.
  • The Linux version of KeePassX has a handy feature: “auto-fill”. (I haven’t tried the Windows version, and I couldn’t get this feature to work in the Mac version, though that could’ve been my fault…)
    In the menu, go to Extras/Settings…, select the Advanced tab and place the cursor inside the field next to “Global Auto-type Shortcut”. Then, press the keys you wish to use for a keyboard shortcut—I use Ctrl-Shift-A—and this will appear in the field.
    Now, when you visit a site where you have to log in, select the entry for that site in the KeePassX list, place the cursor inside the username field on the form in your Web browser, and type your keyboard shortcut. If all goes well, the fields should be populated from KeePassX, and the form submitted. This usually works in Firefox, though with all the “variables” involved, “your mileage may vary”.

Hope these are of use, and if you’re looking for an app to keep your Web and other passwords secure, I warmly recommend giving KeePassX a whirl.

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