Debugging

Generally speaking, if you can build a program from source, it will run on your UNIX; if you cannot, the program will not run. When you have the source code, however, a sufficiently experienced sysadmin can learn why a program won't build or run. In many cases, the problem is simple and can be fixed with minimal effort. (This is one reason why access to source code is important.)

Back when every UNIX administrator was a programmer, this debugging absorbed a major portion of the admin's time. Every UNIX was slightly different, so all systems administrators had to understand the platform a program had been written for, and its differences from their platform, before they could hope to get a chunk of code to run. The duplication of effort was truly monstrous.

Slowly, tools such as autoconf and configure were created to help address these cross−platform issues. Still, not every program used these tools, and when they broke, the administrator returned to square one. Systems administrators had to edit source code and Makefiles just to have a chance of making programs work.

[1]It is possible to build software on a foreign platform via something called "cross−compiling." Cross−compiling demands you know much more about building software than we want to go into here, though.

The Ports and Packages System

The FreeBSD ports and packages system is a software−building system designed to simplify the configuration and installation of software. It started addressing program−building issues back in 1995.

Ports are instructions for compiling software on FreeBSD, and packages are simply precompiled ports. Packages install more quickly, and can save you time. Ports install more slowly, but will accept changes from your environment (changes you specify in /etc/make.conf).

The basic idea behind the ports and packages system is very simple: If software must be modified to run on BSD, then the modifications should be automated. If you're going to automate the changes, you might as well record what the program includes so you can easily install and uninstall it. And since you have a software−building process that produces exactly the same result each time, and you've recorded everything that the program−building process creates, you can copy the binaries and install them on any similar FreeBSD system. This is the basis of the ports and packages system.

The whole system is called the ports collection, the ports tree, or even just ports. When someone uses one of these terms, he's generally including the ports, the system for building ports, and packages.

Ports

A port is a set of instructions on how to apply fixes to, or patch, a set of sourcecode files. By combining patches with installation instructions, FreeBSD can maintain a complete record of everything the software−install process has done. This frees you from struggling to install a program, and allows you to concentrate on making the program work properly instead.

If you followed the installation hints in Chapter 1, you installed the ports tree in /usr/ports, something like the following listing:

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# ls /usr/ports/
INDEX	cad	games	misc	ukrainian
LEGAL	chinese	german	net	vietnamese
Makefile	comms	graphics	news	www
Mk	converters	hebrew	palm	x11
README	databases	irc	picobsd	x11−clocks
Templates	deskutils	japanese	print	x11−fm
Tools	devel	java	russian	x11−fonts
archivers	distfiles	korean	science	x11−servers
astro	editors	lang	security	x11−toolkits
audio	emulators	mail	shells	x11−wm
benchmarks	french	math	sysutils
biology	ftp	mbone	textproc
#

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If you don't see something like this listing in usr/ports, you need to install the ports to continue. To do so, visit your nearest FTP FreeBSD server, and check the directory for the FreeBSD version you're running; you'll find a directory called ports. Look for two files, ports.tgz and install.sh; download both and run install.sh. When you've finished, you should see something like the previous listing.

The directories shown in the previous list are software categories. Each category contains a further layer of directories, and each directory under a category is a port of a piece of software. Since FreeBSD has almost 6,000 ports as I write this, this directory tree is vital to keeping them in any sort of order!

The following listing shows the contents of the "astro" ports category, where astronomical software supported by FreeBSD is kept. (Yes, people use FreeBSD for serious astronomical work.) This category might not be of much interest to most people, but it has the serious advantage of being small enough to print in a book. Some ports categories, such as "www", have hundreds of entries.

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#ls /usr/ports/astro/
Makefile	p5−Astro−SunTime	sunclock
SETIsupport	p5−Astro−Sunrise	tkseti
dgpsip	p5−GPS	wmglobe
ephem	p5−Geo−METAR	wmmoonclock
fooseti	pkg	wmspaceweather
gkrellmearth	pyweather	wmsun
gkrellmoon	rmap	x3arth
glunarclock	saoimage	xearth
jday	sattrack	xephem
ksetiwatch	seti_applet	xglobe
luna	setiathome	xphoon
openuniverse	sscalc	xplanet
p5−Astro−MoonPhase	stars	xtide
#

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Finding Software

Some of the categories have hundreds of ports, so how can you ever find anything? For an index of ports, see /usr/ports/INDEX, which contains a list of all the ports, in alphabetical order. Each port is described on a single line, with fields separated by pipe symbols (|).

While this is a convenient format for the various system tools to access, it's not particularly human−readable. For you to start reading the index file, you need to know what each field means. (Some of the fields appear redundant, but they're needed for reasons we'll get to later.) Here's a sample entry, with a line break at each delimiter to make it easier to understand:

...............................................................................................

vfooseti−0.6.5|

w/usr/ports/astro/fooseti|

x/usr/local|

yGTK+ frontend to SETI@Home|

z/usr/ports/astro/fooseti/pkg−descr| { [e-mail]|

| astro|

} XFree86−3.3.6_9 gettext−0.10.35 glib−1.2.10_3 gtk−1.2.10_2| ~ XFree86−3.3.6_9 gettext−0.10.35 glib−1.2.10_3 gtk−1.2.10_2|

• http://www−personal.engin.umich.edu/~agorski/fooseti

...............................................................................................

The first field (v) is the name and version number of the software package—in this case, fooseti version 0.6.5. The second field (w) is the directory where the port can be found (/usr/ports/astro/fooseti), and the next (x) is the default installation location. The fooseti port, for example, installs under /usr/local unless the administrator chooses a separate location. Following is a short description of the software package (y).

The fifth field (z) gives the location of a file, with a more complete description of the software. The email address field ({) lists the software's FreeBSD maintainer, someone who has assumed responsibility for making sure the port works properly. Next is the category (|), the directory under /usr/ports where the port directory lives.

Field eight (}) contains the list of ports needed to build this software. Many ports require other ports as prerequisites; for example, a piece of software might require a special version of make to build, called a build dependency. This example needs XFree86, gettext, glib, and gtk.

The ninth field (~)lists the ports needed to run this software. Many ports have such runtime dependencies in addition to the build dependencies, meaning that when the program runs, it tries to call other programs. If the program's dependencies are not found, the program cannot run. Our example has identical buildtime and runtime dependencies, though this is not always the case.

Last is the URL of the program's home page (•).

Note If you forget what each field means, make print−index will print out a much longer, but prettier, list of everything in the index.

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Finding by Name

Knowing what the index contains is nice, but how can it help you find a piece of software?

Well, if you know the exact name of the software package, you can use a simple grep command to pick it out. This is quick and easy, but it only works if you're comfortable with grep(1) and you know the exact name of the software in the FreeBSD ports tree. For example, to find staroffice you might enter this grep command:

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# grep −i ^staroffice INDEX staroffice−5.1a|/usr/ports/editors/staroffice5|/usr/local|Integrated wordprocessor/dbase/spreadheet/drawing/chart/browser|/usr/ports/editors/staroffice5/ pkg−descr|[e-mail]|editors linux|unzip−5.42|linux_base−6.1| staroffice−5.2|/usr/ports/editors/staroffice52|/usr/local|Integrated wordprocessor/dbase/spreadheet/drawing/chart/browser|/usr/ports/editors/staroffice52 /pkg−descr|[e-mail]|editors linux|linux_base−6.1||

#

...............................................................................................

This output shows us that we have two different versions of staroffice available, version 5.1a and version 5.2. Both are available under /usr/ports/editors, in staroffice5 and staroffice52, respectively.

Finding by Partial Name

If you don't know the software's exact name, try the ports collection's search feature. The make search command scans the ports index for you, searching either for the name of a port or ports where a word appears.

For example, if you're looking for the popular Midnight Commander file manager, you might try this command:

...............................................................................................

# make search name=midnight

#

...............................................................................................

Well, that was less than helpful.

Finding by Keyword

If that search doesn't work, as in the preceding example, you can try a more generic search using the key option. This search scans more fields, returning more hits. (Though if you're searching for a common word, the key search can provide far too much information.)

Here's how to use the key search on the word "midnight":

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# make search key=midnight

Port: mc−4.5.54_2

Path: ? /usr/ports/misc/mc

Info: Midnight Commander, a free Norton Commander Clone

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