TweetFollow Us on Twitter

MacTech Magazine Article Archives

Volume Number: 19 (2003)
Issue Number: 5
Column Tag: Mac OS X Programming Secrets

Mac OS X: Wading In

by Scott Knaster

This is the first episode of Mac OS X Programming Secrets, and there are about 12 billion possible topics to write about in this rich, largely unexplored operating system that's gradually but inevitably taking over the Macintosh world. Most months, this column will focus on cool programming things, especially the nifty newest ones that Apple tosses our way. Rather than present a programming topic this month, we're going to discuss a collection of tips and schticks you can use to improve your daily OS X work and play, whether writing code or just nerding out. Some of these might be familiar to you, but I'm guessing you'll find at least one or two that will make you say "cool!" (or at least "oh").

Our Heritage

Before we start in with the tips, let's take a moment to establish some common ground. Mac OS X is a strange and wonderful aggregation of very different technologies: Macintosh meets Unix, by way of NeXT. Apple performed a remarkable engineering feat in lifting up Mac OS and shoving Unix into place underneath. Not only does this affect the tools and applications we use, it's also reflected in the human community of Mac programmers. Some of us, including me, grew up with the "classic" Mac, while other OS X devotees come from the land of Unix. Perhaps the luckiest/smartest OS X programmers are those who stuck with NeXTSTEP through all these years. And the better OS X gets, the more Windows programmers are peeking into the tent to see what all the fuss is about.

Since the Mac was introduced, one of its biggest attractions has been that it avoided the command line goofiness that used to rule the world, so a lot of us have spent the past 20 years mostly staying away from Unixy things. Of course, the user interface for Mac programming tools has always been a source of controversy: sure (says the argument), pretty and easy user interfaces are good enough for mere users, but real programmers are different. They need the power and control of command-line tools. This debate has resulted in divergent philosophies in programming tools, with slick integrated development environments (IDEs) on one side and command-line shells on the other. Most modern programmers end up with some of each, with graphical user interfaces on some tools and command line connections to others, although there are purists who live and die in the shell and won't go near a pretty IDE even if you offer them unlimited Jolt Cola.

I'm an old Mac guy who saw the GUI light in the early '80s. I prefer the boulevard ride that Aqua provides, but I've spent many an hour careening through command lines and I'm not averse to going there when power, control, or necessity demands, as it often does in these early days of OS X. Plus, figuring out something nerdy thrills me as much as it does the next geek. So while I'll usually be looking for an easy Aqua solution to problems in this column, we'll have plenty of fun under the hood in the command line too. The great thing about Mac OS X is that it lets us mix and match Aqua apps with command line tools, and it even provides some bridges between the worlds.

Terminal Condition

The Terminal application is the trap door that gets you from nice Aqualand, where all the natives know how to point and click, to the shell, that place of exposed wiring and ductwork, absolute power, and little protective fencing. As you likely know by now, Apple puts Terminal in the Utilities folder of your Applications folder, where your mother won't stumble upon it. In a Unix pathname, you would refer to this location as:

   /Applications/Utilities/

Terminal starts a session with a Unix shell, an interactive program that lets you issue commands to your computer, which it then obeys precisely and without question. Of course, your idea of the command might not always be the same as the shell's interpretation - but it always wins. By default, Terminal uses a shell called tsch, one of several that come with your Mac.

You'll spend a lot of your Terminal time typing pathnames of files and directories. For example, if you wanted to see a list of Terminal's fellow utilities, you could type

ls /Applications/Utilities/ 

ls is the shell command for listing files in a directory, and /Applications/Utilities/ is the argument, or the directory we want to see listed. (I don't want to get off on a rant here, but many shell command names aren't just non-mnemonic, they're wildly inconsistent. But there are zillions of programmers who know them by heart and have been using them since Reagan was president, so things are not likely to change. If you haven't grown up using Unix, you will likely never memorize most of them, so the best thing to do is get used to it and consider adding a sticky note next to your computer until you learn the ones you need.)

To make your pathname-typing life easier, the shell includes a shortcut for autocompleting pathnames. If you press Tab while typing a pathname, the shell will kindly fill out the rest of the pathname, up to the next slash, according to the files in the directory you're addressing. We'll illustrate this valuable trick by getting a listing of /Applications/Utilities/ so we can see what other nerdy goodies are contained inside. First, let's take a look at the root directory:

[neb:~] scott% ls /
Applications                                Users
Applications (Mac OS 9)                     Volumes
Cleanup At Startup                          automount
Desktop (Mac OS 9)                          bin
Desktop DB                                  cores
Desktop DF                                  dev
Desktop Folder                              etc
Developer                                   mach
Documents                                   mach.sym
Library                                     mach_kernel
Network                                     private
System                                      radiohead
System Folder                               sbin
Temporary Items                             tmp
TheVolumeSettingsFolder                     usr
Trash                                       var

As you probably already knew, the shell shortcut for your root folder is a slash, and if you didn't know that, you just picked up a handy tip. To try the Tab autocomplete feature, open a new Terminal window and type the following:

ls /Lib

and then press Tab (don't press return). You'll see that the shell completes the pathname up to the next slash and makes the command ls /Library/ , saving us from typing the rest of the file name. Thanks, shell! We could have gotten the same result by typing ls /L and then pressing Tab. After pressing Tab, the insertion point is now at the end of the second slash, so we could keep typing from there, but we'll just press return to see the contents of /Library/ . Thanks to my buddy ZZ for the clue ticket on this one.

Now that we've seen how the Tab shortcut works, let's get that listing of the Utilities directory. We can reuse the Tab trick at every subdirectory level if we want. Start out by typing ls /App and then pressing Tab. The shell fills out the line to read:

ls /Applications

and the Mac beeps at us! So rude! What's going on? Take a look at the listing of the root directory above. Note that there are two entries that start with "App": "Applications" and "Applications (Mac OS 9)". When this happens, the autocomplete feature can't be sure which one we want, so it completes as much as possible, until the names start to differ, and it beeps to let us know that it couldn't finish the job. In this case, the names are the same up until the end of the word "Applications", so that much gets filled in for us. In this case, that happens to be just what we want at this directory level. So we continue our quest to get a listing of /Applications/Utilities/ by typing a little more, until the line reads:

ls /Applications/Util

We can then press Tab and the rest of the line is filled out: ls /Applications/Utilities/ . From there, we just press Return and we finally see the listing of Terminal and the Utilities (which would make a great band name, by the way).

[neb:~] scott% ls /Applications/Utilities/
AirPort Admin Utility.app         DigitalColor Meter.app
Keychain Access.app               AirPort Setup Assistant.app
Directory Access.app              NetInfo Manager.app
Apple System Profiler.app         Disk Copy.app
Network Utility.app               Asia Text Extras
Disk Utility.app                  ODBC Admin.app
Audio MIDI Setup.app              Display Calibrator.app
Print Center.app                  Bluetooth File Exchange.app
EarthLink                         Process Viewer.app
Bluetooth Serial Utility.app      Grab.app
Software Restore.app              Bluetooth Setup Assistant.app
Installer.app                     StuffIt Expander.app
CPU Monitor.app                   IntelliPoint UnInstaller.app
Terminal.app                      ColorSync Utility.app
Java                              iPod 1.2.6 Updater
Console.app                       Key Caps.app

We're History

The thoughtful shell keeps track of all the commands you issue, just in case you ever need them again. If you want to repeat the last command you gave, just press the up-arrow. You'll see the previous command, along with all its options and arguments, retyped on the command line. Press return to make it so.

There's a lot more to this trick. You can keep pressing up-arrow to get older and older commands restored to the command line, all the way back to the start of your shell session. This is incredibly handy if you have to type a long, complicated command: with judicious use of the arrow keys (down-arrow moves forward through your old commands), you'll never have to type it more than once per shell session.

If you don't want to use the arrow keys to move through commands one at a time, you can use the history command see every darn command (up to 100) you've issued during this shell session. Here's what it looks like:

[neb:~] scott% history 30
    50  14:41   ls /
    51  14:41   cd %
    52  14:41   cd ~
    53  14:41   ls /
    54  14:43   ls ~
    55  14:43   ls /
    56  14:51   ls /Applications ( Mac OS 9 ) /Cleanup
    57  14:53   ls /Applications\ \(Mac\ OS\ 9\)/
    58  14:53   ls
    59  14:54   ls /Library/
    60  14:54   ls /Library/
    61  15:11   ls /Library
    62  15:14   ls /Applications/Utilities/
    63  15:14   ls /Applications/
    64  15:17   ls /Applications/Utilities/
    65  15:18   man ls
    66  15:19   ls /
    67  15:19   ls /Applications/Utilities/
    68  15:25   history
    69  15:30   man history
    70  15:30   man history
    71  15:30   history
    72  15:30   history -a
    73  15:31   history -h
    74  15:31   history -r
    75  15:33   cat video
    76  15:33   set
    77  15:34   history
    78  15:35   history -30
    79  15:35   history 30

Wow, talk about Big Brother watching you! In this listing, we've actually used one of history's command line options to limit its output to the last 30 commands rather than showing the whole tedious spew. The history command has several other interesting options, including -r to show the list in reverse order (oldest commands first), and various options for saving commands to files for easy recycling.

The history output is good for more than just amusement and quiet contemplation. Each line starts with a number, and you can repeat that line's command just by typing an exclamation point (which, if you want to be taken seriously as a Unix geek, you should call "bang") followed by the line number. For example, to repeat the command that history shows as line 67, you can type !67 and press return.

Cruising in Comfort

As you do your Terminal business, you'll find yourself moving from one directory to another. You probably know that every active shell session has a working directory, which is the directory that's assumed for commands if no directory is specified. For example, if you type ls without any arguments, you'll get a listing of your working directory. You can find out your working directory by using the pwd (print working directory) command.

Whenever you type a command that operates on a file, you have two choices for how to specify the file's directory: you can either give a complete pathname to the file, or you can change your working directory, and then commands will look for files in that directory. Compare these two ways of deleting a file, using the shell command rm (remove):

rm ~/Documents/Work/invoices/Dec02.doc

vs.

cd ~/Documents/Work/invoices/
rm Dec02.doc

Both produce the same result, deleting the file Dec02.doc. Changing working directories is a good strategy if you're going to be living in that directory for awhile. It's also useful when you're just getting started with the shell, just to make sure you're working in the directory you think you are. This is especially true if you're doing destructive things like deleting files. When you're just learning to find your way around, you can add to your comfort level by setting the working directory before operating on files. For further comfort, you can use ls after changing working directories as a sort of reality check that you're in the right directory. Don't worry about taking an extra step or two to make sure you're doing the right thing, especially before you do something drastic like deleting files.

Don't Forget: It's a Mac

Mac OS X is a marriage of the Mac and Unix, but a lot of folks tend to forget that you can take advantage of standard Mac stuff when you're using Terminal. For example, you can open as many windows as you want. Every window is a separate shell session. This is useful if you have a shell session or two that's running a lengthy command, but you still want to be able to interact with the shell for directory listings and so on. You can even use different shells in various windows. In Figure 1, we have three shell windows open, each running a different shell. As a Mac guy, a shell is pretty much a shell to me, but I know that each one has its own quirks, charms, and accursed blemishes, so you should choose the one you like the best.


Figure 1. Each shell window is running a different shell: tcsh, bash, and zsh.

Copying and pasting text works just dandy in Terminal windows. You can copy text in any application and paste it into a shell window - the text appears at the insertion point. Drag and drop is another Mac-like feature you can use with the shell. You can select text in a window and drag it to the insertion point, and it will be inserted. This works whether the text comes from a Terminal window - even the same one as the destination - or another application. What's more - and this is really cool - if you drag a file from the Finder and drop it into a shell window, the file's name appears at the insertion point. Somebody was really thinkin' there!

Of course, pure fun is one of the best Macintosh features. Even though Terminal is perhaps the most utilitarian, plain application you can imagine, it's got some fun built in, too. One way to have a good time with Terminal is by customizing the appearance of its windows. In Terminal, choose Terminal --> Window Settings, then pick Color from the Popup at the top of the dialog. This dialog lets you choose different colors for regular, bold, and selected text, the background, and the cursor. You can set color combinations that are gaudy, bizarre, and completely illegible if that's your desire. For even more joy, use the Transparency slider to set how opaque you want the Terminal window to be. The more transparent it gets, the more the window beneath it shines through. This has a very high cool factor indeed, although it's easy to go a little overboard on the transparency. On the other hand, cranking up the transparency is a great way to have some fun with the company Unix god who wants to try out your Mac. (For best results, combine this with the Desktop Preferences setting that changes the desktop picture every 5 seconds.) See Figure 2 to get an idea of how this looks.


Figure 2. Maybe this is a little too transparent.

Go Forth and Nerdify

As you continue on your way toward mastering OS X, you can use the tips in this column and discover more of your own. The more time you spend in Terminal, the more comfortable you'll feel driving around. Remember that for some operations, you have the option of working in the shell or in an Aqua application. For example, when you need to create or edit a text file, you can use a Mac app like TextEdit or BBEdit, you can dive into a command line editor like Pico or vi, or you can switch between all of the above. Which is better? That depends largely on what you're comfortable with. If you come from the Unix tradition, real live Unix editors are there for you. If you're a Mac kinda person, you can use apps that are familiar to you and you won't have to worry about learning vi commands unless you're looking for something interesting to do on a rainy day.

During your Terminal touring, you should become good friends with the man (manual) command, which provides built-in documentation for shell commands. To use it, type man followed by the command you want to learn about, such as man ls or man rm. (Using man occasionally produces some fascinating commands, such as man set, man machine, man top, and even man man. Who says Unix has no sense of humor?)

While you're fooling with Terminal, try lots of stuff that you read about in man pages, but be careful about changing things you didn't really want to change. Play around, experiment, take it slow, and hey, let's be careful out there - but don't forget to have fun!


Scott Knaster has been writing about Macs for as long as there have been Macs. Scott's books How To Write Macintosh Software and Macintosh Programming Secrets were required reading for Mac programmers for more than a decade. Scott wrote developer books for General Magic and worked on Mac software for Microsoft. Scott's books have been translated into Japanese and Pascal. Scott has every issue of Mad magazine, which explains a lot.

 
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

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
ExpanDrive 4.2.1 - 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
Adobe After Effects CC 2014 13.2 - Creat...
After Effects CC 2014 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous After Effects customer). After Effects CS6 is still available... Read more

Latest Forum Discussions

See All

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 »
A Bunch of Halfbrick Games Are Going Fre...
A Bunch of Halfbrick Games Are Going Free for the Holidays Posted by Ellis Spice on December 19th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

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
Holiday sales this weekend: MacBook Pros for...
 B&H Photo has new MacBook Pros on sale for up to $300 off MSRP as part of their Holiday pricing. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1699... Read more
Holiday sales this weekend: MacBook Airs for...
B&H Photo has 2014 MacBook Airs on sale for up to $120 off MSRP, for a limited time, for the Thanksgiving/Christmas Holiday shopping season. Shipping is free, and B&H charges NY sales tax... Read more
Holiday sales this weekend: iMacs for up to $...
B&H Photo has 21″ and 27″ iMacs on sale for up to $200 off MSRP including free shipping plus NY sales tax only. B&H will also include a free copy of Parallels Desktop software: - 21″ 1.4GHz... Read more
Holiday sales this weekend: Mac minis availab...
B&H Photo has new 2014 Mac minis on sale for up to $80 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 1.4GHz Mac mini: $459 $40 off MSRP - 2.6GHz Mac mini: $629 $70 off MSRP... Read more
Holiday sales this weekend: Mac Pros for up t...
B&H Photo has Mac Pros on sale for up to $500 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2599, $400 off MSRP - 3.5GHz 6-core Mac Pro: $3499, $... Read more
Save up to $400 on MacBooks with Apple Certif...
The Apple Store has Apple Certified Refurbished 2014 MacBook Pros and MacBook Airs available for up to $400 off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Save up to $300 on Macs, $30 on iPads with Ap...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
iOS and Android OS Targeted by Man-in-the-Mid...
Cloud services security provider Akamai Technologies, Inc. has released, through the company’s Prolexic Security Engineering & Research Team (PLXsert), a new cybersecurity threat advisory. The... 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.