This is a list of pointers for newcomers to Mac OS X. It is mostly geared
towards people coming from UNIX and UNIX-like environments.
Mac OS X is based on Darwin – a BSD UNIX under the
hood. Darwin has a number of subtle differences from traditional UNIX
Orientation and Moving Around
A Terminal emulator can be found in /Applications/Utilities.
Many common software packages come with the the distribution, including ssh,
emacs, perl, python, ruby, etc. Those that don’t often build directly from
Dragging a file or folder onto the Terminal will input the pathname to the
The open command will open a pathname as if it had been opened from the
Finder. For example, open foo will open the file foo with the appropriate
helper. open . will open a Finder window for the current directory. This is
particularly useful when poking around areas of the file system which are
otherwise hidden from the Finder. In addition, the -a flag causes the Finder
to search for and open an application, e.g. open -a Terminal.app (opens the
first Terminal.app found, regardless of its location) or open -a BBEdit.app
./foo.txt (opens foo.txt from the current directory in the first BBEdit
“Classic” Mac apps are those compiled to run on Mac OS 9 or earlier. These
don’t work on Intel-based Macs and, in general, aren’t used any more. However,
some will still run under OS X on a PowerPC based Mac if you have the Classic
environment (a hosted OS 9 runtime) installed. Older PowerPC based Macs can
also boot into OS 9.
“Universal” Mac apps are those compiled to run on both PowerPC and Intel based
Macs. This is largely irrelevant, as Apple hasn’t shipped a PowerPC based Mac
in years. The exception is that modern versions of Mac OS X won’t run PowerPC
apps, so you may need to find an updated version of the app if you wish to
Most system “extensions” go in a subdirectory of /Library or ~/Library.
Putting it in the former makes it available to everyone, in the latter just
to that user. Apple-provided system extensions go into /System/Library.
(n.b. “Extensions” sometimes refers to a specific type of OS X component that
typically indicates use of a kernel extension, but many people use the term
imprecisely, which can lead to confusion.)
Differences from other platforms
Through version 10.7, Mac OS X ships with X11 (possibly as an optional install),
but the default UI doesn’t use it. Apple’s X11 comes with a window manager that
gives X apps Mac-style windows.
Apps are a collection of files in a folder with the .app extension. The Finder
knows what to do with these. If you want to poke around inside, select “Show
Package Contents” from the contextual menu, or cd into them. Some apps with
generic names are sometimes referred to by the full package name to indicate
the mac specific version (e.g. “Mail.app”).
The system relies heavily on internal services for configuration, rather than
static text files. Editing the standard UNIX configuration files may not have
any effect, and is discouraged.
Most of the normal UNIX file paths are hidden in the Finder. For example,
/usr/bin is there, and accessible from the command line, but /usr doesn’t
show up in Finder views.
UNIX servers often have their config files in odd places within /Library.
Darwin uses two boot systems: an older script-based boot system using
directories of files stored in /System/Library/StartupItems and
for more info) and a newer system built on dependency graphs,
launchd, which is intended
to replace all the various methods of automatically starting software in the
environment. launchd has some limitations (in particular, it doesn’t deal
with apps that need to be shutdown via another process, such as apache
with apachectl), but is otherwise a complete solution for launching
software and managing what’s running.
The default file system install is HFS+. UFS is also available as an option.
There are upsides and downsides to both:
HFS+ is a dual-fork journaled fs with metadata support. HFS+ is a
fragmenting FS, although with hot-file clustering the need for
explicit de-fragmentation is pretty low. By default HFS+ is case-insensitive
but case-preserving. You can configure it as fully case-sensitive by
reformatting, but this is a very uncommon configuration and many user apps
UFS is UFS. It doesn’t fragment, but it doesn’t have the dual fork support
that various apps need.
Command line tools (e.g. ls, mv, tar) have varying levels of support
for HFS+ resource forks and metadata, so it pays to be careful when working
with Mac files from the command line.
Configuring your environment
The user default web browser and email client are defined in the preference
panes of Apple’s shipping applications (Safari and Mail, respectively). If
you want to use different apps (e.g. Firefox and/or Thunderbird) you can use
the Apple apps to define what gets opened for http:, https: and mailto: links.
Alternatively you can use
More Internet, a
preference pane which lets you set most protocol handlers.
Don’t move apps which the system installs. Updaters may try to update blankly
into the space where it thinks your app is, leaving you with half an updated
app. Most third party developers use a “drag install” (move the app wherever
you want, the app doesn’t care), avoiding these problems. Apple is reputed to
be working on an installer that tracks where you moved things, but for now
that doesn’t work.
If you are using a laptop and take it with you, get to know the Locations
submenu of the Apple menu. You can configure multiple logical sets of network
configurations (e.g. “Home at Desk” (ethernet on, fixed IP nothing else),
“Work” (ethernet with work’s DHCP config and proxy server settings), “Bob’s”
(WiFi with Bob’s network/security info), etc.), and switch between them
You can move the dock to different sides of the screen. Third party apps like
TinkerTool will let you pin it
to the beginning or end of its orientation. Most people seem to wind up
sticking it on the right in order to get more vertical space. Many also pin
to the beginning (top, when on the side) so the dock doesn’t jump around as
The system firewall is available in the Security panel in System Preferences.
Note that the Sharing panel will automatically poke holes in the firewall for
services you enable. Note: the system firewall has many
known holes. If you want to
monitor and block outbound connections, get
A panel in System Preferences will let you set which apps to launch when you
log in. In OS X 10.6 it’s the “Login Items” tab under the “Accounts” panel,
though the location changed in past releases. Note that this just deals with
per-login-session items, not with background processes (servers, etc.)
launched at boot time.
Maintenance and Troubleshooting
The Software Update panel in System Preferences (and “Software Update…” menu
item in the Apple menu) gets the latest OS and application updates. You can
use it manually or set it up to check automatically on a daily, weekly or
monthly schedule (sort of: you can’t set the details of the schedule, just
OS X updates may step all over /usr, /etc, /var, etc., but should leave
/usr/local alone. Regardless, you may wish to avoid installing UNIX software
into /usr if you are building it yourself.
The built in disk utility has a “repair disk” function that runs fsck. You
can also run fsck by booting in single-user mode.
DiskWarrior is a third-party disk
utility that is generally good at catching and fixing ugly disk problems.
Yasu bundles many common maintenance
tasks behind a fairly easy to use interface. It is especially worth getting
if you’re supporting other users. Of note: many of these tasks only solve a
small number of specific problems, and are often compared to cargo-cult
debugging. That said, taken together these tasks fix a large number of
specific problems, so the tool turns out to be fairly useful.
File system rot is not-uncommon (although far less common than it used to be).
Try some combination of the following:
Boot in single user mode and run fsck. This is equivalent to running the
Disk Utility’s First Aid function, although possibly a bit more effective.
Boot from the install disk and run the Disk Utility app’s First Aid
function. (You might need to do this if you can’t boot in single user mode
or don’t trust running it from the local disk.)
Some installers and some applications can corrupt your file permissions on the
disk, causing all sorts of quiet problems. Disk Utility has a function for
repairing file permissions, and Yasu lets you run this function with less
hassle. Many people feel that this is a voodoo fix, but they have yet to
explain to me why I should not be concerned when secure.log is world readable,
or the Applications directory is world-writeable.
HFS+ volumes get fragmented, but as of OSX 10.3 the system defrags on the fly,
and uses hot-file clustering to speed disk performance. Accordingly, it
generally isn’t worth de-fragmenting (and it often just makes things worse).
If you must defragment, it’s usually worth running DiskWarrior both before and
after a de-fragmentation operation.
The development environment
(XCode) includes gcc and other
standard development tools. As of XCode 4, the gcc is actually gcc-llvm, as
Apple is moving the toolchain to an llvm-based toolchain. You can get the most
recent version via the App Store.
Fink and MacPorts
are package managers along the lines of the Ports collection. They both also
have GUI front ends. Both these tools install things outside of /usr (Fink in
/sw, DarwinPorts in /opt). Homebrew is a
more bare-bones package manager designed for more technical users. It lets you
pick where to install.
Secrets lets you twiddle with various UI
OS X comes with iChat AV – a
video-conferencing and AIM client (the video-conferencing feature only works
with other iChat AV clients). AOL ported its own AIM client for OS X, but
hasn’t updated it since February of 2004. Many people prefer
Adium – a small, fast, GPLd instant message client
supporting most major IM protocols, as well as OTR encryption.
Aquamacs is a port of Emacs that runs in the Mac UI
Video playback is kind of a mess. The system comes with QuickTime, although
some features (such as MPEG–2 support) cost extra. You can get
DivX and Flip4Mac’s Windows
Media codecs for QuickTime.
MPlayer are third-party players which
support a number of additional codecs. None of these alone will play
everything, but all of them together will play most everything.
The Mozilla apps (Firefox, Thunderbird, etc.) are
available. They’re supported but less well-integrated with the rest of the
system. Camino is a project to wrap the
Gecko browser engine (from Firefox) in a Mac UI, and integrate with the rest
of the system.
Microsoft Internet Explorer is no longer supported (some might argue it wasn’t
really supported when it was supported)
Microsoft Office is available.
TextMate is a popular text editor for Mac OS X that
has been likened to Emacs for its extensibility and programmer-focus.
BBEdit is another
popular text editor for Mac OS X.
a free version of BBEdit (without many of the more powerful features).
Little Snitch is an active
firewall extension that lets you monitor and control outbound connections
(e.g. the app “iThoughtThisWasNotSpyware.app wants to send to host badguy.com.
The Safari Cookies, Safari
ClickToFlash extensions let you
manage cookies, ads, and Flash components, respectively.
Cookie is an
app that lets you automatically mange cookies across many browsers, without
patching the browser at runtime.
You can hold down various keys during boot to cause certain things to happen.
option - bring up a list of volumes to boot from.
c - boot from CD if available.
t - boot as a firewire disk you can access from other machines.
I run a mailing list, OSX Hack which is sort of a
general “geeks using OS X” discussion forum. Topics range from the basic to the
arcane. If you found this document useful you will probably get something out
of the list.