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

BBEdit 11.0.3 - 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
Microsoft Office Preview 15.8 - Popular...
Welcome to the new and modern Microsoft Office for Mac. You will receive regular updates automatically until the official release in the second half of 2015. With the redesigned Ribbon and your... Read more
Yosemite Cache Cleaner 9.0.5 - Clear cac...
Yosemite Cache Cleaner is an award-winning general purpose tool for OS X. YCC makes system maintenance simple with an easy point-and-click interface to many OS X functions. Novice and expert users... Read more
ExpanDrive 4.3.2 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
RapidWeaver 6.0.8 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
Artlantis Studio 5.1.2.7 - 3D rendering...
Artlantis Studio is a unique and ideal tool for performing very high resolution rendering easily and in real time. The new FastRadiosity engine now lets you compute images in radiosity-even in... Read more
MacUpdate Desktop 6.0.5 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
BitTorrent Sync 2.0.82 - Sync files secu...
BitTorrent Sync allows you to sync unlimited files between your own devices, or share a folder with friends and family to automatically sync anything. File transfers are encrypted. Your information... Read more
Google Drive 1.20 - File backup and shar...
Google Drive is a place where you can create, share, collaborate, and keep all of your stuff. Whether you're working with a friend on a joint research project, planning a wedding with your fiancé, or... Read more
Simon 4.0.3 - Monitor changes and crashe...
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

New Publisher Allstar Games Heads West w...
Allstar Games has announced its first mobile title designed for western audiences, Allstar Heroes. The game will be a massive online battle arena (MOBA) that offers dozens of heroes for you to collect and pit against your opponents. As each hero has... | Read more »
RAD Boarding Review
RAD Boarding Review By Jennifer Allen on March 5th, 2015 Our Rating: :: NEARLY RADUniversal App - Designed for iPhone and iPad RAD Boarding isn’t quite one of the greats, but it has potential.   | Read more »
Presenting the International Mobile Gami...
11th Annual International Mobile Gaming Awards ceremony, hosted by actress Allison Haislip, gathered mobile game developers and publishers from around the world. They chose 13 winners out of the 93 nominations. British studio USTWO won the the Grand... | Read more »
AG Drive Review
AG Drive Review By Tre Lawrence on March 5th, 2015 Our Rating: :: FUTURISTIC STREET RACING.Universal App - Designed for iPhone and iPad Futuristic racing… interstellar style.   | Read more »
GDC 2015 – Nightmare Guardians is an Int...
GDC 2015 – Nightmare Guardians is an Interesting Hybrid of MOBA and Lane Defense Posted by Rob Rich on March 5th, 2015 [ permalink ] I have to say that lane defense (i.e. | Read more »
Overkill 3 Review
Overkill 3 Review By Tre Lawrence on March 5th, 2015 Our Rating: :: WHO'S NEXT?Universal App - Designed for iPhone and iPad Cover system gameplay in the third-person.   Developer: Craneballs Price: Free Version Reviewed: 1.1.6... | Read more »
Warner Bros. Interactive Entertainment A...
Warner Bros. has some exciting games coming down the pipe! | Read more »
GDC 2015 – Star Trek Timelines will Prob...
GDC 2015 – Star Trek Timelines will Probably Make Your Inner Trekkie Squeal With Glee Posted by Rob Rich on March 4th, 2015 [ permalink ] Any popular fictional universe has its fair share of fan fiction – where belo | Read more »
Protect Yourself from an Onslaught of Ca...
Surprise Attack Games has announced a Cat-astrophic new physics puzzler called Fort Meow! In the game, a young girl named Nia finds her grandfather’s journal which triggers an all mighty feline attack! Why do the cats want the journal? Who knows,... | Read more »
GDC 2015 – Jelly Reef will be Game Oven’...
GDC 2015 – Jelly Reef will be Game Oven’s Last Hurrah, and it Seems like a Good Note to Go Out on Posted by Rob Rich on March 4th, 2015 [ permalink ] It’s sad knowing that Game Oven ( | Read more »

Price Scanner via MacPrices.net

Roundup of MacBook Air sale prices, models up...
B&H Photo has MacBook Airs on sale for up to $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 11″ 128GB MacBook Air: $799 100 off MSRP - 11″ 256GB MacBook Air: $999 $100... Read more
New Firstrade Mobile App Enables On-The-Go Tr...
Firstrade Securities Inc. has announced its new mobile app, which gives investors immediate access to the company’s trading platform on all mobile devices. The app was developed in-house and was... Read more
Sonnet Introduces USB 3.0 + eSATA Thunderbolt...
Sonnet has announced the launch of its new USB 3.0 + eSATA Thunderbolt Adapter for easy connectivity to USB 3.0 devices and eSATA storage, and USB 3.0 + Gigabit Ethernet Thunderbolt Adapter for easy... Read more
Apple restocks refurbished 27-inch 5K iMacs f...
The Apple Store has restocked Apple Certified Refurbished 27″ 3.5GHz 5K iMacs for $2119 including free shipping. Their price is $380 off the cost of new models, and it’s the lowest price available... Read more
Free Clean Reader Mobile App Hides Swear Word...
The new Clean Reader app, now available in the Apple App Store and Google Play, delivers the opportunity of reading any book without being exposed to profanity. By selecting how clean they want their... Read more
Kinsa Launches “Groups” App to Monitor Illnes...
Kinsa, makers of the first FDA approved app-enabled smartphone thermometer thst won the 2013 Cleveland Clinic Medical Innovation Grand Prize and recently appeared in Apple’s “Parenthood” TV... Read more
iPad: A More Positive Outlook – The ‘Book Mys...
It’s good to hear someone saying positive things about the iPad. I’ve been trying to bend my mind around how Apple’s tablet could have gone from zero to bestselling personal computing device on the... Read more
Mac Pros on sale for up to $279 off MSRP
Amazon has Mac Pros in stock and on sale for up to $279 off MSRP. Shipping is free: - 4-Core Mac Pro: $2725.87, $273 off MSRP (9%) - 6-Core Mac Pro: $3719.99, $279 off MSRP (7%) Read more
Sale! 13-inch Retina MacBook Pros for up to $...
B&H Photo has 13″ Retina MacBook Pros on sale for up to $205 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.6GHz/128GB Retina MacBook Pro: $1219.99 save $80 - 13″ 2.... Read more
Another Tranche Of IBM MobileFirst For iOS Ap...
IBM has announced the next expansion phase for  its IBM MobileFirst for iOS portfolio, with a troika of new apps to address key priorities for the Banking and Financial Services, Airline and Retail... Read more

Jobs Board

*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* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
Position Opening at *Apple* - Apple (United...
…Summary** As a Specialist, you help create the energy and excitement around Apple products, providing the right solutions and getting products into customers' hands. You Read more
Position Opening at *Apple* - Apple (United...
**Job Summary** The Apple Store is a retail environment like no other - uniquely focused on delivering amazing customer experiences. As an Expert, you introduce people Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.