TweetFollow Us on Twitter

X11 Tweaks

Volume Number: 19 (2003)
Issue Number: 5
Column Tag: Section 7

X11 Tweaks

Making X11 Play Nicely on the Mac

by Rich Morin

Tweaking X11 isn't for everyone. You'll find yourself editing configuration files, rummaging through voluminous FAQs and man pages, and whining piteously to folks on assorted mailing lists. Even if you're a dedicated hacker, you may begin to wonder whether this is the way you want to spend your time.

More to the point, you may not need to tweak X11. If, like many users, you only run commands by means of the X11 "Applications" menu, adding a few commands to the list may be all you ever need to do. The syntax may be arcane, but the commands are short and the effects of a mistake are limited to the command involved.

Even if you want to run apps from the command line, there are ways to avoid hacking. If you're only running X11 apps locally (i.e., on your desktop machine), you can start them up by means of Apple's open-x11 command. This is an (undocumented) X11 analog to open(1), which starts up OSX apps. If you have X11 running, you can start up a local copy of xclock(1) by typing the following at any shell prompt:

open-x11 xclock

In short, most X11 tweaking is entirely optional. I would suggest, however, that you put /usr/bin/X11R6 into your PATH variable. This will allow you read the X11 man pages and run X11 apps without the need for open-x11.

If you're a csh(1) user, add the following to your ~/.login file:

setenv PATH "${PATH}:/usr/X11R6/bin"

If you're a bash(1) user, add the following to your $HOME/.bash_login file:

PATH="${PATH}:/usr/X11R6/bin"

By some cute trickery, described in manpath(1), the same information is to set up manual page lookups. Basically, if PATH contains a bin directory, the corresponding man directory is searched when man(1) is run.

So much for X11 tweaking, folks. That's it, all done, move along, nothing more to see here...

Still Here?

If you have more stringent requirements (or aren't entranced with Apple's "stock" X11 configuration), you may be interested in hearing about some useful "tweaks" I've run across. Even if you don't share my situation or tastes, it's useful to know how to customize X11.

Until someone provides a GUI-based configuration tool, modifying X11's behavior will require users to edit text files, specifically, start-up scripts. The "system-wide" X11 start-up script is named /etc/X11/xinit/xinitrc; personal ones go in ~/.xinitrc. Let's walk through the system version, so you'll know which lines do what.

If xinitrc were a normal, executable script, the first line would tell the system which interpreter (i.e., /bin/sh) to use on it. In fact, things are a bit weirder than that. /bin/sh is nominally the path to sh(1), the Bourne shell; like many other vendors, however, Apple has chosen to substitute bash(1), the GNU Project's Bourne-Again SHell, running in "POSIX" mode. Normally, this substitution is invisible, but it's nice to know what's what.

In this particular case, however, the line is simply treated as a comment. Apple's X11 implementation (like many others) always uses /bin/sh to interpret its start-up files, so changing the requested interpreter wouldn't make any difference at all!

The first two characters (#!) of the script's initial line, incidentally, are commonly pronounced "pound bang" or perhaps "shebang". The second line is a comment which contains version information from rcs(1), the "revision control system" that was used in maintaining this file.

#!/bin/sh
# $Id: xinitrc,v 1.2 2003/02/27 19:03:30 jharper Exp $

The next four lines define some shell variables, used to specify file locations. $HOME is an "environment variable" which is set at login time to the user's home directory. /etc is a traditional location for Unix control files; /etc/X11/xinit, predictably, is an X11-specific subdirectory for initialization files.

userresources=$HOME/.Xresources
usermodmap=$HOME/.Xmodmap
sysresources=/etc/X11/xinit/.Xresources
sysmodmap=/etc/X11/xinit/.Xmodmap

Next, the script checks for the existence of each file, executing a specific command if the file is present. xmodmap(1) is a utility for modifying keymaps and pointer button mappings; xrdb(1) is a resource database utility.

# merge in defaults and keymaps
if [ -f $sysresources ]; then
    xrdb -merge $sysresources
fi
if [ -f $sysmodmap ]; then
    xmodmap $sysmodmap
fi
if [ -f $userresources ]; then
    xrdb -merge $userresources
fi
if [ -f $usermodmap ]; then
    xmodmap $usermodmap
fi

With all of the settings loaded, the server is in a position to start up some programs. First, it starts up an instance of xterm(1), a terminal emulator. The ampersand at the end of the line forces the program to run in the background (that is, detached from the shell process that is interpreting this script).

Finally, the script starts quartz-wm(1), the Aqua Window Manager for the X Window System on OS X. The exec command tells the current shell session to replace itself by the window manager (as opposed to waiting around for the window manager to finish). Consequently, any commands placed after the exec line will be ignored.

# start some nice programs
xterm &
# start the window manager
exec quartz-wm

Customization

As discussed in an earlier column ("X11: A C of Window Systems"), X11's goal is to provide "mechanism, not policy". This makes it highly customizable, but it also means that there are a great number of possible configurations, depending on each user's preferences and the methods chosen to achieve them. In short, don't expect Macintosh-style simplicity.

Although the system-wide control files are important to understand, I'd recommend strongly against editing them. Apple is quite likely to change one or more of these files in an update, so your changes might quietly disappear. Also, if there are any other users on your system, it might be considered bad form to give them a "non-standard" configuration.

Instead, create personal control files (~/.Xmodmap, ~/.Xresources, and/or ~/.xinitrc). If you only want to add or override some default settings, the first two of these may be sufficient. The start-up script will use any settings you put into your personal files, after the system-wide settings have been loaded.

To change X11's start-up behavior, copy /etc/X11/xinit/xinitrc to ~/.xinitrc (be sure to include the initial period!), then edit the copy. When the X11 server detects ~/.xinitrc, it will use the personal script instead of the system-wide script, so be sure to include any lines (from the original script) that you want to have run!

Rich's X11 Tweaks

Here is a personal set of tweaks, based on my own situation and preferences. They won't be the best choice for every situation, but they work well for me and show, in any case, how this sort of thing can be done.

My goal is to have a consistently Mac-like environment, allowing me to edit files and run commands on both my desktop Mac (cerberus) and a remote FreeBSD box (cfcl). I should be able to run X11 apps on either the desktop or remote machine, by means of the command line or the X11 server's "Applications" menu.

Most users run X11 apps by means of the mouse, so let's look at setting up some entries in the Applications menu. Because X11 is a network-friendly window system, we can put in either local or remotely-executed commands:

xclock -title cerberus
ssh -X cfcl xclock -title cfcl
xterm -bg 'pink' -geometry =80x60

The first two commands, above, start up instances of xclock(1) on cerberus and cfcl, respectively. The "-title" option, described in X(1), is used to indicate which machine the app is running on. The last command sets up an 80 column by 60 line xterm(1), using a garish pink background color (to distinguish it from Terminal windows).

The $PATH modifications described at the beginning of the article let me look up X11 commands and run them from the command line. Speaking of command lines, however, let's set up Terminal (yay!) as a substitute for xterm (feh!).

The default xinitrc file tells the X11 server to start up an xterm. Because this xterm doesn't have the desired characteristics (i.e., preset size and background color), I might as well get rid of it. So, I create a personal start-up file and then comment out the offending line:

# xterm &

I could, if desired, start up some number of xterm windows from this file, specifying their sizes, colors, initial positions, and many other attributes. I'm not going to do this, however, because I seldom want to run xterm at all. The Terminal works just fine for me and xterm's appearance and behavior aren't even faintly Mac-like, so why use it?

Unfortunately, this leaves me with a small problem. X11 applications use an environment variable (DISPLAY) to tell them where they should present their output (and get input such as keyboard and mouse actions). Because the xterm above was being started up by X11, this variable was being set for it automagically. How can I get DISPLAY to be set for Terminal?

If I'm willing to keep a copy of X11 running all the time, there's a really simple solution: run Terminal from the X11 start-up script! As a "child" of X11, the Terminal process will inherit DISPLAY in exactly the same way that xterm (or any other app) would. Terminal goes into the background on its own, incidentally, so we don't need an ampersand:

open /Applications/Utilities/Terminal.app

Obviously, X11 depends heavily on the DISPLAY variable; if the variable gets trashed, bad things will start to happen. Worse, the cause of the problem may not be obvious. So, I wrote a simple "sanity check", which goes into the ~/.login file on the remote machine:

if ($?DISPLAY) xdpyinfo > /dev/null

xdpyinfo(1) is a utility for displaying information about an X11 server. If DISPLAY is set at login time, this program will be run. Although the normal output is discarded, I'll find out about any DISPLAY problems from the program's error messages. (In proper Unix fashion, these are output to standard error, which is not discarded.)

X11 Forwarding

ssh(1) is the modern replacement for telnet(1). It is secure, reliable, and has some very nifty features (one of which we're about to use :-). When I log in to a remote machine, I want any X11 commands I run to display their windows on my desktop machine. This means I need a secure path for the X11 protocol (and I don't want to worry much about how it's done :-).

X11 forwarding is the "silver bullet" that solves this problem. The ssh command (on the desktop machine) exchanges some information with sshd(8), the daemon process on the remote machine. When they're done, there's a secure communication path for my session!

There are two ways to ask for X11 forwarding. Adding the "-X" option to the ssh command line is the simplest, but it only affects a single session. If you want all of your ssh sessions to do forwarding, you can add the following line to the end of /etc/ssh_config, but remember that an update may overwrite the file:

ForwardX11 yes

I decided, instead, to create an alias (in ~/.cshrc) that sets up X11-forwarded ssh sessions on cfcl:

alias cfcl 'ssh -X cfcl'

In any case, I can now start up X11 (with no annoying xterm window showing up) and type commands into convenient, Mac-friendly Terminal windows. Using the "-title" option, described in X(1), I can even identify the machine an app is running on:

rdm@cerberus [~] 1: xclock -title cerberus &
rdm@cerberus [~] 2: cfcl
...
rdm@cfcl [~] 1: xclock -title cfcl &

The result, as shown in the figure, is a pair of clocks. One is running on cerberus (my Mac OS X desktop machine); the other is running on cfcl (the FreeBSD box downstairs). Both show up on my desktop, however, proving that I got everything right (except keeping the system clocks synchronized :-).


Another Approach

One objection to this approach is that it requires the X11 server to run all the time. I don't use X11 all that much, so this seems a bit heavy-handed. On the other hand, it is both simpler and safer than the method I'm about to describe. In short, proceed further at your own risk...

There are many ways to set environment variables. If you add the following line to your ~/.login file, it will get run for each new Terminal window:

if (! $?DISPLAY) setenv DISPLAY ':0'

This code is a bit subtle, so an explanation may be in order. If DISPLAY is already set (as it would be if we were coming in from an xterm), we don't want to destroy the existing setting. Otherwise, however, we're free to set up the variable.

Note: Some programs (e.g., GNU Emacs) take the existence of DISPLAY as a guarantee that an X11 server is available. If Emacs tries to talk to a nonexistent server, predictably bad things will happen. Of course, you can unset the variable before you start up Emacs, but that may seem a bit kludgy:

% (unsetenv DISPLAY; emacs foo)

Don't tell any real X11 enthusiasts that you're setting DISPLAY, by the way, unless you're ready for an extended lecture on how things are supposed to be done. For that matter, this is a klunky and somewhat fragile hack, but it works for me (:-).

Resources

I'd like to thank the patient and helpful folks on X11-users (the X11 for Mac OS X discussion list) for helping me find the information for this article. If you're planning to use X11 on OSX, be sure to join this list (http://lists.apple.com/mailman/listinfo/x11-users).

I'd also recommend that you familiarize yourself with Apple's "X11 Public Beta FAQ", the "X11: Frequently Asked Questions" thread on The MacOSXhints Forums, and the "X11 for OS X Unofficial FAQ":

http://developer.apple.com/qa/qa2001/qa1232.html

http://forums.macosxhints.com/showthread.php?s=&threadid=8704

http://www.misplaced.net/fom/X11

Even if you're not planning to do X11 development, you should grab a copy of Apple's "X11 for Mac OS X Public Beta SDK". Most X11 packages are distributed in source form; if you want to build them, you'll need the SDK!

Speaking of X11 (and other) packages for OSX, Fink is a popular and frequently recommended source for pre-compiled binaries, etc:

http://fink.sourceforge.net


Rich Morin has been using computers since 1970, Unix since 1983, and Mac-based Unix since 1986 (when he helped Apple create A/UX 1.0). When he isn't writing this column, Rich runs Prime Time Freeware (www.ptf.com), a publisher of books and CD-ROMs for the Free and Open Source software community. Feel free to write to Rich at rdm@ptf.com.

 
AAPL
$111.78
Apple Inc.
-0.87
MSFT
$47.66
Microsoft Corpora
+0.14
GOOG
$516.35
Google Inc.
+5.25

MacTech Search:
Community Search:

Software Updates via MacUpdate

NeoOffice 2014.6 - Mac-tailored, OpenOff...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
LibreOffice 4.3.5.2 - Free Open Source o...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
CleanApp 5.0.0 Beta 5 - Application dein...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Monolingual 1.6.2 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
NetShade 6.1 - Browse privately using an...
NetShade is an Internet security tool that conceals your IP address on the web. NetShade routes your Web connection through either a public anonymous proxy server, or one of NetShade's own dedicated... Read more
calibre 2.13 - Complete e-library manage...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
Mellel 3.3.7 - Powerful word processor w...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
ScreenFlow 5.0.1 - Create screen recordi...
Save 10% with the exclusive MacUpdate coupon code: AFMacUpdate10 Buy now! ScreenFlow is powerful, easy-to-use screencasting software for the Mac. With ScreenFlow you can record the contents of your... Read more
Simon 4.0 - Monitor changes and crashes...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
BBEdit 11.0.2 - Powerful text and HTML e...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more

Latest Forum Discussions

See All

Galaxy Trucker Pocket (Games)
Galaxy Trucker Pocket 1.0.8 Device: iOS iPhone Category: Games Price: $2.99, Version: 1.0.8 (iTunes) Description: Galaxy Truckers Wanted!================================================================= (5/5) "Galaxy Trucker isn’t... | Read more »
Make your own Tribez Figures (and More)...
Make your own Tribez Figures (and More) with Toyze Posted by Jessica Fisher on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
So Many Holiday iOS Sales Oh My Goodness...
The holiday season is in full-swing, which means a whole lot of iOS apps and games are going on sale. A bunch already have, in fact. Naturally this means we’re putting together a hand-picked list of the best discounts and sales we can find in order... | Read more »
It’s Bird vs. Bird in the New PvP Mode f...
It’s Bird vs. Bird in the New PvP Mode for Angry Birds Epic Posted by Jessica Fisher on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Telltale Games and Mojang Announce Minec...
Telltale Games and Mojang Announce Minecraft: Story Mode – A Telltale Games Series Posted by Jessica Fisher on December 19th, 2014 [ permalink ] | Read more »
WarChest and Splash Damage Annouce Their...
WarChest and Splash Damage Annouce Their New Game: Tempo Posted by Jessica Fisher on December 19th, 2014 [ permalink ] WarChest Ltd and Splash Damage Ltd are teaming up again to work | Read more »
BulkyPix Celebrates its 6th Anniversary...
BulkyPix Celebrates its 6th Anniversary with a Bunch of Free Games Posted by Jessica Fisher on December 19th, 2014 [ permalink ] BulkyPix has | Read more »
Indulge in Japanese cuisine in Cooking F...
Indulge in Japanese cuisine in Cooking Fever’s new sushi-themed update Posted by Simon Reed on December 19th, 2014 [ permalink ] Lithuanian developer Nordcurrent has yet again updated its restaurant simulat | Read more »
Badland Daydream Level Pack Arrives to C...
Badland Daydream Level Pack Arrives to Celebrate 20 Million Downloads Posted by Ellis Spice on December 19th, 2014 [ permalink ] | Read more »
Far Cry 4, Assassin’s Creed Unity, Desti...
Far Cry 4, Assassin’s Creed Unity, Destiny, and Beyond – AppSpy Takes a Look at AAA Companion Apps Posted by Rob Rich on December 19th, 2014 [ permalink ] These day | Read more »

Price Scanner via MacPrices.net

Holiday sale: 13-inch 128GB MacBook Air for $...
 Best Buy has the 2014 13-inch 1.4GHz 128GB MacBook Air on sale for $849.99, or $150 off MSRP, on their online store. Choose free home shipping or free local store pickup (if available). Price valid... Read more
13-inch 2.6GHz Retina MacBook Pro on sale for...
Best Buy has lowered their price on the 2014 13″ 2.6GHz/128GB Retina MacBook Pro to $1149.99 on their online store for a limited time. That’s $150 off MSRP and the lowest price available for this... Read more
Kodak Returns to CES With New Consumer Produ...
Former photography colossus Kodak is returning to CES for the first time in three years where the Kodak booth (#21818 South Hall 1) will showcase a wide range of innovative, imaging-related products... Read more
Invaluable Launches New Eponymously -Named A...
Invaluable, the world’s largest online live auction marketplace, hhas announced the official launch of the Invaluable app for iPad, now available for download in the iTunes App Store. Invaluable... Read more
IDC Reveals Worldwide Mobile Enterprise Appli...
International Data Corporation (IDC) last week hosted the IDC FutureScape: Worldwide Mobile Enterprise Applications and Solutions 2015 Predictions Web conference. The session provided organizations... Read more
Hello Vino Wine App Launches “Safe Ride Home”...
Hello Vino has announced addition of a new “Get a Safe Ride Home” feature in its Food & Drink app with a direct connection to Uber, the technology platform that connects users with rides. The... Read more
DEVON-technologies Releases DEVONthink To Go...
Coeur d’Alene, Idaho based DEVON-technologies, LLC has updated DEVONthink To Go, its mobile companion to DEVONthink, to version 1.5. The update includes an iOS 8 extension, compatibility with the... Read more
The Apple Store offering free next-day shippi...
The Apple Store is now offering free next-day shipping on all in stock items if ordered before 12/23/14 at 10:00am PT. Local store pickup is also available within an hour of ordering for any in stock... Read more
It’s 1992 Again At Sony Pictures, Except For...
Techcrunch’s John Biggs interviewed a Sony Pictures Entertainment (SPE) employee, who quite understandably wished to remain anonymous, regarding post-hack conditions in SPE’s L.A office, explaining “... Read more
OtterBox Defender Series Case For iPad mini 3...
With their innovative Touch ID technology and ultrathin profile, the latest tranche of Apple iPads are more desirable than ever, and OtterBox has just announced the Defender Series custom-engineered... Read more

Jobs Board

*Apple* Store Leader Program (US) - Apple, I...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on experience, Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.