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.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Duplicate Annihilator 5.7.5 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator... Read more
BusyContacts 1.0.2 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
Capture One Pro 8.2.0.82 - RAW workflow...
Capture One Pro 8 is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 300 high-end cameras -- straight out of the box. It... Read more
Backblaze 4.0.0.872 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac.With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Little Snitch 3.5.2 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
Monolingual 1.6.4 - 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. If you use your computer in only one (human) language, you... Read more
CleanApp 5.0 - Application deinstaller a...
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
Fantastical 2.0 - Create calendar events...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event details... Read more
Cocktail 8.2 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Direct Mail 4.0.4 - Create and send grea...
Direct Mail is an easy-to-use, fully-featured email marketing app purpose-built for OS X. It lets you create and send great looking email campaigns. Start your newsletter by selecting from a gallery... Read more

Appy to Have Known You - Lee Hamlet Look...
Being at 148Apps these past 2 years has been an awesome experience that has taught me a great deal, and working with such a great team has been a privilege. Thank you to Rob Rich, and to both Rob LeFebvre and Jeff Scott before him, for helping me... | Read more »
MLB Manager 2015 (Games)
MLB Manager 2015 5.0.14 Device: iOS Universal Category: Games Price: $4.99, Version: 5.0.14 (iTunes) Description: Guide your favorite MLB franchise to glory! MLB Manager 2015, officially licensed by MLB.com and based on the award-... | Read more »
Breath of Light (Games)
Breath of Light 1.0.1421 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1421 (iTunes) Description: Hold a quiet moment. Breath of Light is a meditative and beautiful puzzle game with a hypnotic soundtrack by... | Read more »
WWE WrestleMania Tags into the App Store
Are You ready to rumble? The official WWE WrestleMania app, by World Wrestling Entertainment, is now available. Now you can get all your WrestleMania info in one place before anyone else. The app offers details on superstar signings, interactive... | Read more »
Bio Inc's New Expansion is Infectin...
Bio Inc., by DryGin Studios, is the real time strategy game where you infect a human body with the worst virus your evil brain can design. Recently, the game was updated to add a whole lot of new features. Now you can play the new “Lethal”... | Read more »
The Monocular Minion is Here! Despicable...
Despicable Me: Minion Rush, by Gameloft, is introducing a new runner to the mix in their latest update. Now you can play as Carl, the prankster minion. Carl has a few new abilities to play with, including running at a higher speed from the start.... | Read more »
Dungeon of Madness (Games)
Dungeon of Madness 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Dungeon of Madness is an action game where you rotate tiles to create our own route. Help the hero by connecting the... | Read more »
Filters for iPhone (Photography)
Filters for iPhone 1.0 Device: iOS iPhone Category: Photography Price: $.99, Version: 1.0 (iTunes) Description: | Read more »
Jump'N'Shoot Attack (Games)
Jump'N'Shoot Attack 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: A mobile game for gamers! Join Louise Lightfoot, the legendary "Master of Jumping and Shooting", on her mission to save... | Read more »
Space Bounties Inc. (Games)
Space Bounties Inc. 1.4 Device: iOS Universal Category: Games Price: $1.99, Version: 1.4 (iTunes) Description: SuperGameDroid: 4/5 "Satisfying futuristic RPG combat, high replay value, and a heavy dose of nostalgia make Space... | Read more »

Price Scanner via MacPrices.net

13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
Save up to $80 on iPad Air 2s, NY tax only, f...
 B&H Photo has iPad Air 2s on sale for $80 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469.99 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
iMacs on sale for up to $205 off MSRP
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
Färbe Technik Offers iPhone Battery Charge LI...
Färbe Technik, which manufactures and markets of mobile accessories for Apple, Blackberry and Samsung mobile devices, is offering tips on how to keep your iPhone charged while in the field: •... Read more
Electronic Recyclers International CEO Urges...
Citing a recent story on CNBC about concerns some security professionals have about the forthcoming Apple Watch, John Shegerian, Chairman and CEO of Electronic Recyclers International (ERI), the... Read more
Save up to $380 with Apple refurbished iMacs
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
Mac minis on sale for up to $75 off, starting...
MacMall has Mac minis on sale for up to $75 off MSRP including free shipping. Their prices are the lowest available for these models from any reseller: - 1.4GHz Mac mini: $459.99 $40 off - 2.6GHz Mac... Read more
College Student Deals: Additional $50 off Mac...
Take an additional $50 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through April 11, 2015. Anyone with a valid .EDU email address can take advantage... Read more
Mac Pros on sale for up to $260 off MSRP
B&H Photo has Mac Pros on sale for up to $260 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2799, $200 off MSRP - 3.5GHz 6-core Mac Pro: $3719.99... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more

Jobs Board

DevOps Software Engineer - *Apple* Pay, iOS...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring 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
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Lead *Apple* Solutions Consultant - Retail...
**Job Summary** Job Summary The Lead ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.