aboutsummaryrefslogtreecommitdiff
path: root/en_US.ISO_8859-1/books/developers-handbook/book.sgml
diff options
context:
space:
mode:
Diffstat (limited to 'en_US.ISO_8859-1/books/developers-handbook/book.sgml')
-rw-r--r--en_US.ISO_8859-1/books/developers-handbook/book.sgml2257
1 files changed, 2249 insertions, 8 deletions
diff --git a/en_US.ISO_8859-1/books/developers-handbook/book.sgml b/en_US.ISO_8859-1/books/developers-handbook/book.sgml
index 8aacd1d42a..bd58d4a25a 100644
--- a/en_US.ISO_8859-1/books/developers-handbook/book.sgml
+++ b/en_US.ISO_8859-1/books/developers-handbook/book.sgml
@@ -1,7 +1,7 @@
<!--
The FreeBSD Documentation Project
- $FreeBSD: doc/en_US.ISO_8859-1/books/developers-handbook/book.sgml,v 1.4 2000/11/06 10:22:11 murray Exp $
+ $FreeBSD: doc/en_US.ISO_8859-1/books/developers-handbook/book.sgml,v 1.5 2000/11/06 13:52:26 murray Exp $
-->
<!DOCTYPE BOOK PUBLIC "-//FreeBSD//DTD DocBook V3.1-Based Extension//EN" [
@@ -205,14 +205,2255 @@
<part id="Basics">
<title>Basics</title>
- <chapter id="compilation">
- <title>Compilation</title>
+ <chapter id="programming-tools">
+ <title>Programming Tools</title>
- <para>This will include things like: compilation, makefiles, .mk
- files, basic debugging, linking, secure programming
- guidelines, style(9), CVS, diff, patch, etc.</para>
+ <para><emphasis>This chapter was written by James Raynard.
+ Modifications for the Developer's Handbook by Murray Stokely.
+ </emphasis></para>
+
+ <sect1><title>Synopsis</title>
+
+ <para>This document is an introduction to using some of the
+ programming tools supplied with FreeBSD, although much of it
+ will be applicable to many other versions of Unix. It does
+ <emphasis>not</emphasis> attempt to describe coding in any
+ detail. Most of the document assumes little or no previous
+ programming knowledge, although it is hoped that most
+ programmers will find something of value in it</para>
+
+ </sect1>
+
+ <sect1><title>Introduction</title>
+
+ <para>FreeBSD offers an excellent development environment.
+ Compilers for C, C++, and Fortran and an assembler come with the
+ basic system, not to mention a Perl interpreter and classic Unix
+ tools such as <command>sed</command> and <command>awk</command>.
+ If that is not enough, there are many more compilers and
+ interpreters in the Ports collection. FreeBSD is very
+ compatible with standards such as <acronym>POSIX</acronym> and
+ <acronym>ANSI</acronym> C, as well with its own BSD heritage, so
+ it is possible to write applications that will compile and run
+ with little or no modification on a wide range of
+ platforms.</para>
+
+ <para>However, all this power can be rather overwhelming at
+ first if you've never written programs on a Unix platform
+ before. This document aims to help you get up and running,
+ without getting too deeply into more advanced topics. The
+ intention is that this document should give you enough of the
+ basics to be able to make some sense of the
+ documentation.</para>
+
+ <para>Most of the document requires little or no knowledge of
+ programming, although it does assume a basic competence with
+ using Unix and a willingness to learn!</para>
+
+ </sect1>
+
+ <sect1>
+ <title>Introduction to Programming</title>
+
+ <para>A program is a set of instructions that tell the computer
+ to do various things; sometimes the instruction it has to
+ perform depends on what happened when it performed a previous
+ instruction. This section gives an overview of the two main
+ ways in which you can give these instructions, or
+ <quote>commands</quote> as they are usually called. One way
+ uses an <firstterm>interpreter</firstterm>, the other a
+ <firstterm>compiler</firstterm>. As human languages are too
+ difficult for a computer to understand in an unambiguous way,
+ commands are usually written in one or other languages specially
+ designed for the purpose.</para>
+
+ <sect2>
+ <title>Interpreters</title>
+
+ <para>With an interpreter, the language comes as an environment,
+ where you type in commands at a prompt and the environment
+ executes them for you. For more complicated programs, you can
+ type the commands into a file and get the interpreter to load
+ the file and execute the commands in it. If anything goes
+ wrong, many interpreters will drop you into a debugger to help
+ you track down the problem.</para>
+
+ <para>The advantage of this is that you can see the results of
+ your commands immediately, and mistakes can be corrected
+ readily. The biggest disadvantage comes when you want to
+ share your programs with someone. They must have the same
+ interpreter, or you must have some way of giving it to them,
+ and they need to understand how to use it. Also users may not
+ appreciate being thrown into a debugger if they press the
+ wrong key! From a performance point of view, interpreters can
+ use up a lot of memory, and generally do not generate code as
+ efficiently as compilers.</para>
+
+ <para>In my opinion, interpreted languages are the best way to
+ start if you have not done any programming before. This kind
+ of environment is typically found with languages like Lisp,
+ Smalltalk, Perl and Basic. It could also be argued that the
+ Unix shell (<command>sh</command>, <command>csh</command>) is itself an
+ interpreter, and many people do in fact write shell
+ <quote>scripts</quote> to help with various
+ <quote>housekeeping</quote> tasks on their machine. Indeed, part
+ of the original Unix philosophy was to provide lots of small
+ utility programs that could be linked together in shell
+ scripts to perform useful tasks.</para>
+ </sect2>
+
+ <sect2>
+ <title>Interpreters available with FreeBSD</title>
+
+ <para>Here is a list of interpreters that are available as
+ <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/">FreeBSD
+ packages</ulink>, with a brief discussion of some of the
+ more popular interpreted languages.</para>
+
+ <para>To get one of these packages, all you need to do is to
+ click on the hotlink for the package, then run</para>
+
+ <screen>&prompt.root; <userinput>pkg_add <replaceable>package name</></userinput>
+ </screen>
+
+ <para>as root. Obviously, you will need to have a fully
+ functional FreeBSD 2.1.0 or later system for the package to
+ work!</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><acronym>BASIC</acronym></term>
+
+ <listitem>
+ <para>Short for Beginner's All-purpose Symbolic
+ Instruction Code. Developed in the 1950s for teaching
+ University students to program and provided with every
+ self-respecting personal computer in the 1980s,
+ <acronym>BASIC</acronym> has been the first programming
+ language for many programmers. It's also the foundation
+ for Visual Basic.</para>
+
+ <para>The <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/bwbasic-2.10.tgz">Bywater
+ Basic Interpreter</ulink> and the <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/pbasic-2.0.tgz">Phil
+ Cockroft's Basic Interpreter</ulink> (formerly Rabbit
+ Basic) are available as FreeBSD <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/">FreeBSD
+ packages</ulink></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Lisp</term>
+
+ <listitem>
+ <para>A language that was developed in the late 1950s as
+ an alternative to the <quote>number-crunching</quote>
+ languages that were popular at the time. Instead of
+ being based on numbers, Lisp is based on lists; in fact
+ the name is short for <quote>List Processing</quote>.
+ Very popular in AI (Artificial Intelligence)
+ circles.</para>
+
+ <para>Lisp is an extremely powerful and sophisticated
+ language, but can be rather large and unwieldy.</para>
+
+ <para>FreeBSD has <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/gcl-2.0.tgz">GNU
+ Common Lisp</ulink> available as a package.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Perl</term>
+
+ <listitem>
+ <para>Very popular with system administrators for writing
+ scripts; also often used on World Wide Web servers for
+ writing <acronym>CGI</acronym> scripts.</para>
+
+ <para>The latest version (version 5) comes with FreeBSD.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Scheme</term>
+
+ <listitem>
+ <para>A dialect of Lisp that is rather more compact and
+ cleaner than Common Lisp. Popular in Universities as it
+ is simple enough to teach to undergraduates as a first
+ language, while it has a high enough level of
+ abstraction to be used in research work.</para>
+
+ <para>FreeBSD has packages of the <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/elk-3.0.tgz">Elk
+ Scheme Interpreter</ulink>, the <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/mit-scheme-7.3.tgz">MIT
+ Scheme Interpreter</ulink> and the <ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/scm-4e1.tgz">SCM
+ Scheme Interpreter</ulink>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Icon</term>
+
+ <listitem>
+ <para><ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/icon-9.0.tgz">The
+ Icon Programming Language</ulink>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Logo</term>
+
+ <listitem>
+ <para><ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/ucblogo-3.3.tgz">Brian
+ Harvey's LOGO Interpreter</ulink>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Python</term>
+
+ <listitem>
+ <para><ulink
+ URL="ftp://ftp.FreeBSD.org:pub/FreeBSD/packages/lang/python-1.2">The
+ Python Object-Oriented Programming
+ Language</ulink></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </sect2>
+
+ <sect2>
+ <title>Compilers</title>
+
+ <para>Compilers are rather different. First of all, you write
+ your code in a file (or files) using an editor. You then run
+ the compiler and see if it accepts your program. If it did
+ not compile, grit your teeth and go back to the editor; if it
+ did compile and gave you a program, you can run it either at a
+ shell command prompt or in a debugger to see if it works
+ properly.
+
+ <footnote>
+ <para>If you run it in the shell, you may get a core
+ dump.</para>
+ </footnote></para>
+
+ <para>Obviously, this is not quite as direct as using an
+ interpreter. However it allows you to do a lot of things
+ which are very difficult or even impossible with an
+ interpreter, such as writing code which interacts closely with
+ the operating system&mdash;or even writing your own operating
+ system! It's also useful if you need to write very efficient
+ code, as the compiler can take its time and optimise the code,
+ which would not be acceptable in an interpreter. And
+ distributing a program written for a compiler is usually more
+ straightforward than one written for an interpreter&mdash;you
+ can just give them a copy of the executable, assuming they
+ have the same operating system as you.</para>
+
+ <para>Compiled languages include Pascal, C and C++. C and C++
+ are rather unforgiving languages, and best suited to more
+ experienced programmers; Pascal, on the other hand, was
+ designed as an educational language, and is quite a good
+ language to start with. Unfortunately, FreeBSD doesn't have
+ any Pascal support, except for a Pascal-to-C converter in the
+ ports.</para>
+
+ <para>As the edit-compile-run-debug cycle is rather tedious when
+ using separate programs, many commercial compiler makers have
+ produced Integrated Development Environments
+
+ (<acronym>IDE</acronym>s for short). FreeBSD does not have an
+ <acronym>IDE</acronym> as such; however it is possible to use Emacs
+ for this purpose. This is discussed in <xref
+ linkend="emacs">.</para>
+ </sect2>
+
+
+ </sect1>
+
+
+ <sect1>
+ <title>Compiling with <command>cc</command></title>
+
+ <para>This section deals only with the GNU compiler for C and C++,
+ since that comes with the base FreeBSD system. It can be
+ invoked by either <command>cc</command> or <command>gcc</command>. The
+ details of producing a program with an interpreter vary
+ considerably between interpreters, and are usually well covered
+ in the documentation and on-line help for the
+ interpreter.</para>
+
+ <para>Once you've written your masterpiece, the next step is to
+ convert it into something that will (hopefully!) run on FreeBSD.
+ This usually involves several steps, each of which is done by a
+ separate program.</para>
+
+ <procedure>
+ <step>
+ <para>Pre-process your source code to remove comments and do
+ other tricks like expanding macros in C.</para>
+ </step>
+
+ <step>
+ <para>Check the syntax of your code to see if you have obeyed
+ the rules of the language. If you have not, it will
+ complain!</para>
+ </step>
+
+ <step>
+ <para>Convert the source code into assembly
+ language&mdash;this is very close to machine code, but still
+ understandable by humans. Allegedly.
+
+ <footnote>
+ <para>To be strictly accurate, <command>cc</command> converts the
+ source code into its own, machine-independent
+ <firstterm>p-code</firstterm> instead of assembly language at
+ this stage.</para>
+ </footnote></para>
+ </step>
+
+ <step>
+ <para>Convert the assembly language into machine
+ code&mdash;yep, we are talking bits and bytes, ones and
+ zeros here.</para>
+ </step>
+
+ <step>
+ <para>Check that you have used things like functions and
+ global variables in a consistent way. For example, if you
+ have called a non-existent function, it will
+ complain.</para>
+ </step>
+
+ <step>
+ <para>If you are trying to produce an executable from several
+ source code files, work out how to fit them all
+ together.</para>
+ </step>
+
+ <step>
+ <para>Work out how to produce something that the system's
+ run-time loader will be able to load into memory and
+ run.</para>
+ </step>
+
+ <step>
+ <para>Finally, write the executable on the file system.</para>
+ </step>
+ </procedure>
+
+ <para>The word <firstterm>compiling</firstterm> is often used to refer to
+ just steps 1 to 4&mdash;the others are referred to as
+ <firstterm>linking</firstterm>. Sometimes step 1 is referred to as
+ <firstterm>pre-processing</firstterm> and steps 3-4 as
+ <firstterm>assembling</firstterm>.</para>
+
+ <para>Fortunately, almost all this detail is hidden from you, as
+ <command>cc</command> is a front end that manages calling all these
+ programs with the right arguments for you; simply typing</para>
+
+ <screen>&prompt.user; <userinput>cc foobar.c</>
+ </screen>
+
+ <para>will cause <filename>foobar.c</filename> to be compiled by all the
+ steps above. If you have more than one file to compile, just do
+ something like</para>
+
+ <screen>&prompt.user; <userinput>cc foo.c bar.c</>
+ </screen>
+
+ <para>Note that the syntax checking is just that&mdash;checking
+ the syntax. It will not check for any logical mistakes you may
+ have made, like putting the program into an infinite loop, or
+ using a bubble sort when you meant to use a binary
+ sort.
+
+ <footnote>
+ <para>In case you didn't know, a binary sort is an efficient
+ way of sorting things into order and a bubble sort
+ isn't.</para>
+ </footnote></para>
+
+ <para>There are lots and lots of options for <command>cc</command>, which
+ are all in the man page. Here are a few of the most important
+ ones, with examples of how to use them.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>-o <replaceable>filename</replaceable></option></term>
+
+ <listitem>
+ <para>The output name of the file. If you do not use this
+ option, <command>cc</command> will produce an executable called
+ <filename>a.out</filename>.
+
+ <footnote>
+ <para>The reasons for this are buried in the mists of
+ history.</para>
+ </footnote></para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc foobar.c</> <lineannotation>executable is <filename>a.out</></>
+&prompt.user; <userinput>cc -o foobar foobar.c</> <lineannotation>executable is <filename>foobar</></>
+ </screen>
+ </informalexample>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-c</option></term>
+
+ <listitem>
+ <para>Just compile the file, do not link it. Useful for toy
+ programs where you just want to check the syntax, or if
+ you are using a <filename>Makefile</filename>.</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -c foobar.c</userinput>
+ </screen>
+ </informalexample>
+
+ <para>This will produce an <firstterm>object file</firstterm> (not an
+ executable) called <filename>foobar.o</filename>. This
+ can be linked together with other object files into an
+ executable.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-g</option></term>
+
+ <listitem>
+ <para>Create a debug version of the executable. This makes
+ the compiler put information into the executable about
+ which line of which source file corresponds to which
+ function call. A debugger can use this information to show
+ the source code as you step through the program, which is
+ <emphasis>very</emphasis> useful; the disadvantage is that
+ all this extra information makes the program much bigger.
+ Normally, you compile with <option>-g</option> while you
+ are developing a program and then compile a <quote>release
+ version</quote> without <option>-g</option> when you're
+ satisfied it works properly.</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -g foobar.c</userinput>
+ </screen>
+ </informalexample>
+
+ <para>This will produce a debug version of the
+ program.
+
+ <footnote>
+ <para>Note, we didn't use the <option>-o</option> flag
+ to specify the executable name, so we will get an
+ executable called <filename>a.out</filename>.
+ Producing a debug version called
+ <filename>foobar</filename> is left as an exercise for
+ the reader!</para>
+ </footnote></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-O</option></term>
+
+ <listitem>
+ <para>Create an optimised version of the executable. The
+ compiler performs various clever tricks to try and produce
+ an executable that runs faster than normal. You can add a
+ number after the <option>-O</option> to specify a higher
+ level of optimisation, but this often exposes bugs in the
+ compiler's optimiser. For instance, the version of
+ <command>cc</command> that comes with the 2.1.0 release of
+ FreeBSD is known to produce bad code with the
+ <option>-O2</option> option in some circumstances.</para>
+
+ <para>Optimisation is usually only turned on when compiling
+ a release version.</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -O -o foobar foobar.c</userinput>
+ </screen>
+ </informalexample>
+
+ <para>This will produce an optimised version of
+ <filename>foobar</filename>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>The following three flags will force <command>cc</command>
+ to check that your code complies to the relevant international
+ standard, often referred to as the <acronym>ANSI</acronym>
+ standard, though strictly speaking it is an
+ <acronym>ISO</acronym> standard.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>-Wall</option></term>
+
+ <listitem>
+ <para>Enable all the warnings which the authors of
+ <command>cc</command> believe are worthwhile. Despite the
+ name, it will not enable all the warnings
+ <command>cc</command> is capable of.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-ansi</option></term>
+
+ <listitem>
+ <para>Turn off most, but not all, of the
+ non-<acronym>ANSI</acronym>&nbsp;C features provided by
+ <command>cc</command>. Despite the name, it does not
+ guarantee strictly that your code will comply to the
+ standard.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><option>-pedantic</option></term>
+
+ <listitem>
+ <para>Turn off <emphasis>all</emphasis>
+ <command>cc</command>'s non-<acronym>ANSI</acronym>&nbsp;C
+ features.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <para>Without these flags, <command>cc</command> will allow you to
+ use some of its non-standard extensions to the standard. Some
+ of these are very useful, but will not work with other
+ compilers&mdash;in fact, one of the main aims of the standard is
+ to allow people to write code that will work with any compiler
+ on any system. This is known as <firstterm>portable
+ code</firstterm>.</para>
+
+ <para>Generally, you should try to make your code as portable as
+ possible, as otherwise you may have to completely re-write the
+ program later to get it to work somewhere else&mdash;and who
+ knows what you may be using in a few years time?</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -Wall -ansi -pedantic -o foobar foobar.c</userinput>
+ </screen>
+ </informalexample>
+
+ <para>This will produce an executable <filename>foobar</filename>
+ after checking <filename>foobar.c</filename> for standard
+ compliance.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><option>-l<replaceable>library</replaceable></option></term>
+
+ <listitem>
+ <para>Specify a function library to be used during when
+ linking.</para>
+
+ <para>The most common example of this is when compiling a
+ program that uses some of the mathematical functions in C.
+ Unlike most other platforms, these are in a separate
+ library from the standard C one and you have to tell the
+ compiler to add it.</para>
+
+ <para>The rule is that if the library is called
+ <filename>lib<replaceable>something</replaceable>.a</filename>,
+ you give <command>cc</command> the argument
+ <option>-l<replaceable>something</replaceable></option>.
+ For example, the math library is
+ <filename>libm.a</filename>, so you give
+ <command>cc</command> the argument <option>-lm</option>.
+ A common <quote>gotcha</quote> with the math library is
+ that it has to be the last library on the command
+ line.</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -o foobar foobar.c -lm</userinput>
+ </screen>
+ </informalexample>
+
+ <para>This will link the math library functions into
+ <filename>foobar</filename>.</para>
+
+ <para>If you are compiling C++ code, you need to add
+ <option>-lg++</option>, or <option>-lstdc++</option> if
+ you are using FreeBSD 2.2 or later, to the command line
+ argument to link the C++ library functions.
+ Alternatively, you can run <command>c++</command> instead
+ of <command>cc</command>, which does this for you.
+ <command>c++</command> can also be invoked as
+ <command>g++</command> on FreeBSD.</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -o foobar foobar.cc -lg++</userinput> <lineannotation>For FreeBSD 2.1.6 and earlier</>
+&prompt.user; <userinput>cc -o foobar foobar.cc -lstdc++</userinput> <lineannotation>For FreeBSD 2.2 and later</>
+&prompt.user; <userinput>c++ -o foobar foobar.cc</userinput>
+ </screen>
+ </informalexample>
+
+ <para>Each of these will both produce an executable
+ <filename>foobar</filename> from the C++ source file
+ <filename>foobar.cc</filename>. Note that, on Unix
+ systems, C++ source files traditionally end in
+ <filename>.C</filename>, <filename>.cxx</filename> or
+ <filename>.cc</filename>, rather than the
+ MS-DOS style
+ <filename>.cpp</filename> (which was already used for
+ something else). <command>gcc</command> used to rely on
+ this to work out what kind of compiler to use on the
+ source file; however, this restriction no longer applies,
+ so you may now call your C++ files
+ <filename>.cpp</filename> with impunity!</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+ <sect2>
+ <title>Common <command>cc</command> Queries and Problems</title>
+
+ <qandaset>
+ <qandaentry>
+ <question>
+ <para>I am trying to write a program which uses the
+ <function>sin()</function> function and I get an error
+ like this. What does it mean?</para>
+
+ <informalexample>
+ <screen>/var/tmp/cc0143941.o: Undefined symbol `_sin' referenced from text segment
+ </screen>
+ </informalexample>
+ </question>
+
+ <answer>
+ <para>When using mathematical functions like
+ <function>sin()</function>, you have to tell
+ <command>cc</command> to link in the math library, like
+ so:</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -o foobar foobar.c -lm</userinput>
+ </screen>
+ </informalexample>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>All right, I wrote this simple program to practice
+ using <option>-lm</option>. All it does is raise 2.1 to
+ the power of 6.</para>
+
+ <informalexample>
+ <programlisting>#include &lt;stdio.h&gt;
+
+int main() {
+ float f;
+
+ f = pow(2.1, 6);
+ printf("2.1 ^ 6 = %f\n", f);
+ return 0;
+}
+ </programlisting>
+ </informalexample>
+
+ <para>and I compiled it as:</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc temp.c -lm</userinput>
+ </screen>
+ </informalexample>
+
+ <para>like you said I should, but I get this when I run
+ it:</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>./a.out</userinput>
+2.1 ^ 6 = 1023.000000
+ </screen>
+ </informalexample>
+
+ <para>This is <emphasis>not</emphasis> the right answer!
+ What is going on?</para>
+ </question>
+
+ <answer>
+ <para>When the compiler sees you call a function, it
+ checks if it has already seen a prototype for it. If it
+ has not, it assumes the function returns an
+ <type>int</type>, which is definitely not what you want
+ here.</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>So how do I fix this?</para>
+ </question>
+
+ <answer>
+ <para>The prototypes for the mathematical functions are in
+ <filename>math.h</filename>. If you include this file,
+ the compiler will be able to find the prototype and it
+ will stop doing strange things to your
+ calculation!</para>
+
+ <informalexample>
+ <programlisting>#include &lt;math.h&gt;
+#include &lt;stdio.h&gt;
+
+int main() {
+...
+ </programlisting>
+ </informalexample>
+
+ <para>After recompiling it as you did before, run
+ it:</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>./a.out</userinput>
+2.1 ^ 6 = 85.766121
+ </screen>
+ </informalexample>
+
+ <para>If you are using any of the mathematical functions,
+ <emphasis>always</emphasis> include
+ <filename>math.h</filename> and remember to link in the
+ math library.</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>I compiled a file called
+ <filename>foobar.c</filename> and I cannot find an
+ executable called <filename>foobar</filename>. Where's
+ it gone?</para>
+ </question>
+
+ <answer>
+ <para>Remember, <command>cc</command> will call the
+ executable <filename>a.out</filename> unless you tell it
+ differently. Use the
+ <option>-o&nbsp;<replaceable>filename</replaceable></option>
+ option:</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>cc -o foobar foobar.c</userinput>
+ </screen>
+ </informalexample>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>OK, I have an executable called
+ <filename>foobar</filename>, I can see it when I run
+ <command>ls</command>, but when I type in
+ <command>foobar</command> at the command prompt it tells
+ me there is no such file. Why can it not find
+ it?</para>
+ </question>
+
+ <answer>
+ <para>Unlike MS-DOS, Unix does not
+ look in the current directory when it is trying to find
+ out which executable you want it to run, unless you tell
+ it to. Either type <command>./foobar</command>, which
+ means <quote>run the file called
+ <filename>foobar</filename> in the current
+ directory</quote>, or change your <systemitem
+ class=environvar>PATH</systemitem> environment
+ variable so that it looks something like</para>
+
+ <informalexample>
+ <screen>bin:/usr/bin:/usr/local/bin:.
+ </screen>
+ </informalexample>
+
+ <para>The dot at the end means <quote>look in the current
+ directory if it is not in any of the
+ others</quote>.</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>I called my executable <filename>test</filename>,
+ but nothing happens when I run it. What is going
+ on?</para>
+ </question>
+
+ <answer>
+ <para>Most Unix systems have a program called
+ <command>test</command> in <filename>/usr/bin</filename>
+ and the shell is picking that one up before it gets to
+ checking the current directory. Either type:</para>
+
+ <informalexample>
+ <screen>&prompt.user; <userinput>./test</userinput>
+ </screen>
+ </informalexample>
+
+ <para>or choose a better name for your program!</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>I compiled my program and it seemed to run all right
+ at first, then there was an error and it said something
+ about <errorname>core dumped</errorname>. What does that
+ mean?</para>
+ </question>
+
+ <answer>
+ <para>The name <firstterm>core dump</firstterm> dates back
+ to the very early days of Unix, when the machines used
+ core memory for storing data. Basically, if the program
+ failed under certain conditions, the system would write
+ the contents of core memory to disk in a file called
+ <filename>core</filename>, which the programmer could
+ then pore over to find out what went wrong.</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>Fascinating stuff, but what I am supposed to do
+ now?</para>
+ </question>
+
+ <answer>
+ <para>Use <command>gdb</command> to analyse the core (see
+ <xref linkend="debugging">).</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>When my program dumped core, it said something about
+ a <errorname>segmentation fault</errorname>. What's
+ that?</para>
+ </question>
+
+ <answer>
+ <para>This basically means that your program tried to
+ perform some sort of illegal operation on memory; Unix
+ is designed to protect the operating system and other
+ programs from rogue programs.</para>
+
+ <para>Common causes for this are:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Trying to write to a <symbol>NULL</symbol>
+ pointer, eg</para>
+
+ <programlisting>char *foo = NULL;
+strcpy(foo, "bang!");
+ </programlisting>
+ </listitem>
+
+ <listitem>
+ <para>Using a pointer that hasn't been initialised,
+ eg</para>
+
+ <programlisting>char *foo;
+strcpy(foo, "bang!");
+ </programlisting>
+
+ <para>The pointer will have some random value that,
+ with luck, will point into an area of memory that
+ isn't available to your program and the kernel will
+ kill your program before it can do any damage. If
+ you're unlucky, it'll point somewhere inside your
+ own program and corrupt one of your data structures,
+ causing the program to fail mysteriously.</para>
+ </listitem>
+
+ <listitem>
+ <para>Trying to access past the end of an array,
+ eg</para>
+
+ <programlisting>int bar[20];
+bar[27] = 6;
+ </programlisting>
+ </listitem>
+
+ <listitem>
+ <para>Trying to store something in read-only memory,
+ eg</para>
+
+ <programlisting>char *foo = "My string";
+strcpy(foo, "bang!");
+ </programlisting>
+
+ <para>Unix compilers often put string literals like
+ <literal>"My string"</literal> into read-only areas
+ of memory.</para>
+ </listitem>
+
+ <listitem>
+ <para>Doing naughty things with
+ <function>malloc()</function> and
+ <function>free()</function>, eg</para>
+
+ <programlisting>char bar[80];
+free(bar);
+ </programlisting>
+
+ <para>or</para>
+
+ <programlisting>char *foo = malloc(27);
+free(foo);
+free(foo);
+ </programlisting>
+ </listitem>
+ </itemizedlist>
+
+ <para>Making one of these mistakes will not always lead to
+ an error, but they are always bad practice. Some
+ systems and compilers are more tolerant than others,
+ which is why programs that ran well on one system can
+ crash when you try them on an another.</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>Sometimes when I get a core dump it says
+ <errorname>bus error</errorname>. It says in my Unix
+ book that this means a hardware problem, but the
+ computer still seems to be working. Is this
+ true?</para>
+ </question>
+
+ <answer>
+ <para>No, fortunately not (unless of course you really do
+ have a hardware problem&hellip;). This is usually
+ another way of saying that you accessed memory in a way
+ you shouldn't have.</para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>This dumping core business sounds as though it could
+ be quite useful, if I can make it happen when I want to.
+ Can I do this, or do I have to wait until there's an
+ error?</para>
+ </question>
+
+ <answer>
+ <para>Yes, just go to another console or xterm, do</para>
+
+ <screen>&prompt.user; <userinput>ps</userinput>
+ </screen>
+
+ <para>to find out the process ID of your program, and
+ do</para>
+
+ <screen>&prompt.user; <userinput>kill -ABRT <replaceable>pid</replaceable></userinput>
+ </screen>
+
+ <para>where
+ <parameter><replaceable>pid</replaceable></parameter> is
+ the process ID you looked up.</para>
+
+ <para>This is useful if your program has got stuck in an
+ infinite loop, for instance. If your program happens to
+ trap <symbol>SIGABRT</symbol>, there are several other
+ signals which have a similar effect.</para>
+ </answer>
+ </qandaentry>
+ </qandaset>
+ </sect2>
+ </sect1>
+
+ <sect1>
+ <title>Make</title>
+
+ <sect2>
+ <title>What is <command>make</command>?</title>
+
+ <para>When you're working on a simple program with only one or
+ two source files, typing in</para>
+
+ <screen>&prompt.user; <userinput>cc file1.c file2.c</userinput>
+ </screen>
+
+ <para>is not too bad, but it quickly becomes very tedious when
+ there are several files&mdash;and it can take a while to
+ compile, too.</para>
+
+ <para>One way to get around this is to use object files and only
+ recompile the source file if the source code has changed. So
+ we could have something like:</para>
+
+ <screen>&prompt.user; <userinput>cc file1.o file2.o</userinput> &hellip; <userinput>file37.c</userinput> &hellip
+ </screen>
+
+ <para>if we'd changed <filename>file37.c</filename>, but not any
+ of the others, since the last time we compiled. This may
+ speed up the compilation quite a bit, but doesn't solve the
+ typing problem.</para>
+
+ <para>Or we could write a shell script to solve the typing
+ problem, but it would have to re-compile everything, making it
+ very inefficient on a large project.</para>
+
+ <para>What happens if we have hundreds of source files lying
+ about? What if we're working in a team with other people who
+ forget to tell us when they've changed one of their source
+ files that we use?</para>
+
+ <para>Perhaps we could put the two solutions together and write
+ something like a shell script that would contain some kind of
+ magic rule saying when a source file needs compiling. Now all
+ we need now is a program that can understand these rules, as
+ it's a bit too complicated for the shell.</para>
+
+ <para>This program is called <command>make</command>. It reads
+ in a file, called a <firstterm>makefile</firstterm>, that
+ tells it how different files depend on each other, and works
+ out which files need to be re-compiled and which ones don't.
+ For example, a rule could say something like <quote>if
+ <filename>fromboz.o</filename> is older than
+ <filename>fromboz.c</filename>, that means someone must have
+ changed <filename>fromboz.c</filename>, so it needs to be
+ re-compiled.</quote> The makefile also has rules telling
+ make <emphasis>how</emphasis> to re-compile the source file,
+ making it a much more powerful tool.</para>
+
+ <para>Makefiles are typically kept in the same directory as the
+ source they apply to, and can be called
+ <filename>makefile</filename>, <filename>Makefile</filename>
+ or <filename>MAKEFILE</filename>. Most programmers use the
+ name <filename>Makefile</filename>, as this puts it near the
+ top of a directory listing, where it can easily be
+ seen.
+
+ <footnote>
+ <para>They don't use the <filename>MAKEFILE</filename> form
+ as block capitals are often used for documentation files
+ like <filename>README</filename>.</para>
+ </footnote></para>
+ </sect2>
+
+ <sect2>
+ <title>Example of using <command>make</command></title>
+
+ <para>Here's a very simple make file:</para>
+
+ <programlisting>foo: foo.c
+ cc -o foo foo.c
+ </programlisting>
+
+ <para>It consists of two lines, a dependency line and a creation
+ line.</para>
+
+ <para>The dependency line here consists of the name of the
+ program (known as the <firstterm>target</firstterm>), followed
+ by a colon, then whitespace, then the name of the source file.
+ When <command>make</command> reads this line, it looks to see
+ if <filename>foo</filename> exists; if it exists, it compares
+ the time <filename>foo</filename> was last modified to the
+ time <filename>foo.c</filename> was last modified. If
+ <filename>foo</filename> does not exist, or is older than
+ <filename>foo.c</filename>, it then looks at the creation line
+ to find out what to do. In other words, this is the rule for
+ working out when <filename>foo.c</filename> needs to be
+ re-compiled.</para>
+
+ <para>The creation line starts with a <token>tab</token> (press
+ the <keycap>tab</keycap> key) and then the command you would
+ type to create <filename>foo</filename> if you were doing it
+ at a command prompt. If <filename>foo</filename> is out of
+ date, or does not exist, <command>make</command> then executes
+ this command to create it. In other words, this is the rule
+ which tells make how to re-compile
+ <filename>foo.c</filename>.</para>
+
+ <para>So, when you type <userinput>make</userinput>, it will
+ make sure that <filename>foo</filename> is up to date with
+ respect to your latest changes to <filename>foo.c</filename>.
+ This principle can be extended to
+ <filename>Makefile</filename>s with hundreds of
+ targets&mdash;in fact, on FreeBSD, it is possible to compile
+ the entire operating system just by typing <userinput>make
+ world</userinput> in the appropriate directory!</para>
+
+ <para>Another useful property of makefiles is that the targets
+ don't have to be programs. For instance, we could have a make
+ file that looks like this:</para>
+
+ <programlisting>foo: foo.c
+ cc -o foo foo.c
+
+install:
+ cp foo /home/me
+ </programlisting>
+
+ <para>We can tell make which target we want to make by
+ typing:</para>
+
+ <screen>&prompt.user; <userinput>make <replaceable>target</replaceable></userinput>
+ </screen>
+
+ <para><command>make</command> will then only look at that target
+ and ignore any others. For example, if we type
+ <userinput>make foo</userinput> with the makefile above, make
+ will ignore the <action>install</action> target.</para>
+
+ <para>If we just type <userinput>make</userinput> on its own,
+ make will always look at the first target and then stop
+ without looking at any others. So if we typed
+ <userinput>make</userinput> here, it will just go to the
+ <action>foo</action> target, re-compile
+ <filename>foo</filename> if necessary, and then stop without
+ going on to the <action>install</action> target.</para>
+
+ <para>Notice that the <action>install</action> target doesn't
+ actually depend on anything! This means that the command on
+ the following line is always executed when we try to make that
+ target by typing <userinput>make install</userinput>. In this
+ case, it will copy <filename>foo</filename> into the user's
+ home directory. This is often used by application makefiles,
+ so that the application can be installed in the correct
+ directory when it has been correctly compiled.</para>
+
+ <para>This is a slightly confusing subject to try and explain.
+ If you don't quite understand how <command>make</command>
+ works, the best thing to do is to write a simple program like
+ <quote>hello world</quote> and a make file like the one above
+ and experiment. Then progress to using more than one source
+ file, or having the source file include a header file. The
+ <command>touch</command> command is very useful here&mdash;it
+ changes the date on a file without you having to edit
+ it.</para>
+ </sect2>
+
+ <sect2>
+ <title>FreeBSD Makefiles</title>
+
+ <para>Makefiles can be rather complicated to write. Fortunately,
+ BSD-based systems like FreeBSD come with some very powerful
+ ones as part of the system. One very good example of this is
+ the FreeBSD ports system. Here's the essential part of a
+ typical ports <filename>Makefile</filename>:</para>
+
+ <programlisting>MASTER_SITES= ftp://freefall.cdrom.com/pub/FreeBSD/LOCAL_PORTS/
+DISTFILES= scheme-microcode+dist-7.3-freebsd.tgz
+
+.include &lt;bsd.port.mk&gt;
+ </programlisting>
+
+ <para>Now, if we go to the directory for this port and type
+ <userinput>make</userinput>, the following happens:</para>
+
+ <procedure>
+ <step>
+ <para>A check is made to see if the source code for this
+ port is already on the system.</para>
+ </step>
+
+ <step>
+ <para>If it isn't, an FTP connection to the URL in
+ <symbol>MASTER_SITES</symbol> is set up to download the
+ source.</para>
+ </step>
+
+ <step>
+ <para>The checksum for the source is calculated and compared
+ it with one for a known, good, copy of the source. This
+ is to make sure that the source was not corrupted while in
+ transit.</para>
+ </step>
+
+ <step>
+ <para>Any changes required to make the source work on
+ FreeBSD are applied&mdash;this is known as
+ <firstterm>patching</firstterm>.</para>
+ </step>
+
+ <step>
+ <para>Any special configuration needed for the source is
+ done. (Many Unix program distributions try to work out
+ which version of Unix they are being compiled on and which
+ optional Unix features are present&mdash;this is where
+ they are given the information in the FreeBSD ports
+ scenario).</para>
+ </step>
+
+ <step>
+ <para>The source code for the program is compiled. In
+ effect, we change to the directory where the source was
+ unpacked and do <command>make</command>&mdash;the
+ program's own make file has the necessary information to
+ build the program.</para>
+ </step>
+
+ <step>
+ <para>We now have a compiled version of the program. If we
+ wish, we can test it now; when we feel confident about the
+ program, we can type <userinput>make install</userinput>.
+ This will cause the program and any supporting files it
+ needs to be copied into the correct location; an entry is
+ also made into a <database>package database</database>, so
+ that the port can easily be uninstalled later if we change
+ our mind about it.</para>
+ </step>
+ </procedure>
+
+ <para>Now I think you'll agree that's rather impressive for a
+ four line script!</para>
+
+ <para>The secret lies in the last line, which tells
+ <command>make</command> to look in the system makefile called
+ <filename>bsd.port.mk</filename>. It's easy to overlook this
+ line, but this is where all the clever stuff comes
+ from&mdash;someone has written a makefile that tells
+ <command>make</command> to do all the things above (plus a
+ couple of other things I didn't mention, including handling
+ any errors that may occur) and anyone can get access to that
+ just by putting a single line in their own make file!</para>
+
+ <para>If you want to have a look at these system makefiles,
+ they're in <filename>/usr/share/mk</filename>, but it's
+ probably best to wait until you've had a bit of practice with
+ makefiles, as they are very complicated (and if you do look at
+ them, make sure you have a flask of strong coffee
+ handy!)</para>
+ </sect2>
+
+ <sect2>
+ <title>More advanced uses of <command>make</command></title>
+
+ <para><command>Make</command> is a very powerful tool, and can
+ do much more than the simple example above shows.
+ Unfortunately, there are several different versions of
+ <command>make</command>, and they all differ considerably.
+ The best way to learn what they can do is probably to read the
+ documentation&mdash;hopefully this introduction will have
+ given you a base from which you can do this.</para>
+
+ <para>The version of make that comes with FreeBSD is the
+ <application>Berkeley make</application>; there is a tutorial
+ for it in <filename>/usr/share/doc/psd/12.make</filename>. To
+ view it, do</para>
+
+ <screen>&prompt.user; <userinput>zmore paper.ascii.gz</userinput>
+ </screen>
+
+ <para>in that directory.</para>
+
+ <para>Many applications in the ports use <application>GNU
+ make</application>, which has a very good set of
+ <quote>info</quote> pages. If you have installed any of these
+ ports, <application>GNU make</application> will automatically
+ have been installed as <command>gmake</command>. It's also
+ available as a port and package in its own right.</para>
+
+ <para>To view the info pages for <application>GNU
+ make</application>, you will have to edit the
+ <filename>dir</filename> file in the
+ <filename>/usr/local/info</filename> directory to add an entry
+ for it. This involves adding a line like</para>
+
+ <programlisting> * Make: (make). The GNU Make utility.
+ </programlisting>
+
+ <para>to the file. Once you have done this, you can type
+ <userinput>info</userinput> and then select
+ <guimenuitem>make</guimenuitem> from the menu (or in
+ <application>Emacs</application>, do <userinput>C-h
+ i</userinput>).</para>
+ </sect2>
+ </sect1>
+
+ <sect1 id="debugging">
+ <title>Debugging</title>
+
+ <sect2>
+ <title>The Debugger</title>
+
+ <para>The debugger that comes with FreeBSD is called
+ <command>gdb</command> (<application>GNU
+ debugger</application>). You start it up by typing</para>
+
+ <screen>&prompt.user; <userinput>gdb <replaceable>progname</replaceable></userinput>
+ </screen>
+
+ <para>although most people prefer to run it inside
+ <application>Emacs</application>. You can do this by:</para>
+
+ <screen><userinput>M-x gdb RET <replaceable>progname</replaceable> RET</userinput>
+ </screen>
+
+ <para>Using a debugger allows you to run the program under more
+ controlled circumstances. Typically, you can step through the
+ program a line at a time, inspect the value of variables,
+ change them, tell the debugger to run up to a certain point
+ and then stop, and so on. You can even attach to a program
+ that's already running, or load a core file to investigate why
+ the program crashed. It's even possible to debug the kernel,
+ though that's a little trickier than the user applications
+ we'll be discussing in this section.</para>
+
+ <para><command>gdb</command> has quite good on-line help, as
+ well as a set of info pages, so this section will concentrate
+ on a few of the basic commands.</para>
+
+ <para>Finally, if you find its text-based command-prompt style
+ off-putting, there's a graphical front-end for it <ulink
+ URL="../../ports/devel.html">xxgdb</ulink> in the ports
+ collection.</para>
+
+ <para>This section is intended to be an introduction to using
+ <command>gdb</command> and does not cover specialised topics
+ such as debugging the kernel.</para>
+ </sect2>
+
+ <sect2>
+ <title>Running a program in the debugger</title>
+
+ <para>You'll need to have compiled the program with the
+ <option>-g</option> option to get the most out of using
+ <command>gdb</command>. It will work without, but you'll only
+ see the name of the function you're in, instead of the source
+ code. If you see a line like:</para>
+
+ <screen>&hellip; (no debugging symbols found) &hellip;
+ </screen>
+
+ <para>when <command>gdb</command> starts up, you'll know that
+ the program wasn't compiled with the <option>-g</option>
+ option.</para>
+
+ <para>At the <command>gdb</command> prompt, type
+ <userinput>break main</userinput>. This will tell the
+ debugger to skip over the preliminary set-up code in the
+ program and start at the beginning of your code. Now type
+ <userinput>run</userinput> to start the program&mdash;it will
+ start at the beginning of the set-up code and then get stopped
+ by the debugger when it calls <function>main()</function>.
+ (If you've ever wondered where <function>main()</function>
+ gets called from, now you know!).</para>
+
+ <para>You can now step through the program, a line at a time, by
+ pressing <command>n</command>. If you get to a function call,
+ you can step into it by pressing <command>s</command>. Once
+ you're in a function call, you can return from stepping into a
+ function call by pressing <command>f</command>. You can also
+ use <command>up</command> and <command>down</command> to take
+ a quick look at the caller.</para>
+
+ <para>Here's a simple example of how to spot a mistake in a
+ program with <command>gdb</command>. This is our program
+ (with a deliberate mistake):</para>
+
+ <programlisting>#include &lt;stdio.h&gt;
+
+int bazz(int anint);
+
+main() {
+ int i;
+
+ printf("This is my program\n");
+ bazz(i);
+ return 0;
+}
+
+int bazz(int anint) {
+ printf("You gave me %d\n", anint);
+ return anint;
+}
+ </programlisting>
+
+ <para>This program sets <symbol>i</symbol> to be
+ <literal>5</literal> and passes it to a function
+ <function>bazz()</function> which prints out the number we
+ gave it.</para>
+
+ <para>When we compile and run the program we get</para>
+
+ <screen>&prompt.user; <userinput>cc -g -o temp temp.c</userinput>
+&prompt.user; <userinput>./temp</userinput>
+This is my program
+anint = 4231
+ </screen>
+
+ <para>That wasn't what we expected! Time to see what's going
+ on!</para>
+
+ <screen>&prompt.user; <userinput>gdb temp</userinput>
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) <userinput>break main</> <lineannotation>Skip the set-up code</>
+Breakpoint 1 at 0x160f: file temp.c, line 9. <lineannotation><command>gdb</command> puts breakpoint at <function>main()</></>
+(gdb) <userinput>run</> <lineannotation>Run as far as <function>main()</></>
+Starting program: /home/james/tmp/temp <lineannotation>Program starts running</>
+
+Breakpoint 1, main () at temp.c:9 <lineannotation><command>gdb</command> stops at <function>main()</></>
+(gdb) <userinput>n</> <lineannotation>Go to next line</>
+This is my program <lineannotation>Program prints out</>
+(gdb) <userinput>s</> <lineannotation>step into <function>bazz()</></>
+bazz (anint=4231) at temp.c:17 <lineannotation><command>gdb</command> displays stack frame</>
+(gdb)
+ </screen>
+
+ <para>Hang on a minute! How did <symbol>anint</symbol> get to be
+ <literal>4231</literal>? Didn't we set it to be
+ <literal>5</literal> in <function>main()</function>? Let's
+ move up to <function>main()</function> and have a look.</para>
+
+ <screen>(gdb) <userinput>up</> <lineannotation>Move up call stack</>
+#1 0x1625 in main () at temp.c:11 <lineannotation><command>gdb</command> displays stack frame</>
+(gdb) <userinput>p i</> <lineannotation>Show us the value of <symbol>i</></>
+$1 = 4231 <lineannotation><command>gdb</command> displays <literal>4231</></>
+ </screen>
+
+ <para>Oh dear! Looking at the code, we forgot to initialise
+ <symbol>i</symbol>. We meant to put</para>
+
+ <programlisting><lineannotation>&hellip;</>
+main() {
+ int i;
+
+ i = 5;
+ printf("This is my program\n");
+<lineannotation>&hellip</>
+ </programlisting>
+
+ <para>but we left the <literal>i=5;</literal> line out. As we
+ didn't initialise <symbol>i</symbol>, it had whatever number
+ happened to be in that area of memory when the program ran,
+ which in this case happened to be
+ <literal>4231</literal>.</para>
+
+ <note>
+ <para><command>gdb</command> displays the stack frame every
+ time we go into or out of a function, even if we're using
+ <command>up</command> and <command>down</command> to move
+ around the call stack. This shows the name of the function
+ and the values of its arguments, which helps us keep track
+ of where we are and what's going on. (The stack is a
+ storage area where the program stores information about the
+ arguments passed to functions and where to go when it
+ returns from a function call).</para>
+ </note>
+ </sect2>
+
+ <sect2>
+ <title>Examining a core file</title>
+
+ <para>A core file is basically a file which contains the
+ complete state of the process when it crashed. In <quote>the
+ good old days</quote>, programmers had to print out hex
+ listings of core files and sweat over machine code manuals,
+ but now life is a bit easier. Incidentally, under FreeBSD and
+ other 4.4BSD systems, a core file is called
+ <filename><replaceable>progname</replaceable>.core</filename> instead of just
+ <filename>core</filename>, to make it clearer which program a
+ core file belongs to.</para>
+
+ <para>To examine a core file, start up <command>gdb</command> in
+ the usual way. Instead of typing <command>break</command> or
+ <command>run</command>, type</para>
+
+ <screen>(gdb) <userinput>core <replaceable>progname</replaceable>.core</userinput>
+ </screen>
+
+ <para>If you're not in the same directory as the core file,
+ you'll have to do <userinput>dir
+ /path/to/core/file</userinput> first.</para>
+
+ <para>You should see something like this:</para>
+
+ <screen>&prompt.user; <userinput>gdb a.out</userinput>
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) <userinput>core a.out.core</userinput>
+Core was generated by `a.out'.
+Program terminated with signal 11, Segmentation fault.
+Cannot access memory at address 0x7020796d.
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+(gdb)
+ </screen>
+
+ <para>In this case, the program was called
+ <filename>a.out</filename>, so the core file is called
+ <filename>a.out.core</filename>. We can see that the program
+ crashed due to trying to access an area in memory that was not
+ available to it in a function called
+ <function>bazz</function>.</para>
+
+ <para>Sometimes it's useful to be able to see how a function was
+ called, as the problem could have occurred a long way up the
+ call stack in a complex program. The <command>bt</command>
+ command causes <command>gdb</command> to print out a
+ back-trace of the call stack:</para>
+
+ <screen>(gdb) <userinput>bt</userinput>
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+#1 0xefbfd888 in end ()
+#2 0x162c in main () at temp.c:11
+(gdb)
+ </screen>
+
+ <para>The <function>end()</function> function is called when a
+ program crashes; in this case, the <function>bazz()</function>
+ function was called from <function>main()</function>.</para>
+ </sect2>
+
+ <sect2>
+ <title>Attaching to a running program</title>
+
+ <para>One of the neatest features about <command>gdb</command>
+ is that it can attach to a program that's already running. Of
+ course, that assumes you have sufficient permissions to do so.
+ A common problem is when you are stepping through a program
+ that forks, and you want to trace the child, but the debugger
+ will only let you trace the parent.</para>
+
+ <para>What you do is start up another <command>gdb</command>,
+ use <command>ps</command> to find the process ID for the
+ child, and do</para>
+
+ <screen>(gdb) <userinput>attach <replaceable>pid</replaceable></userinput>
+ </screen>
+
+ <para>in <command>gdb</command>, and then debug as usual.</para>
+
+ <para><quote>That's all very well,</quote> you're probably
+ thinking, <quote>but by the time I've done that, the child
+ process will be over the hill and far away</quote>. Fear
+ not, gentle reader, here's how to do it (courtesy of the
+ <command>gdb</command> info pages):</para>
+
+ <screen><lineannotation>&hellip</lineannotation>
+if ((pid = fork()) < 0) /* _Always_ check this */
+ error();
+else if (pid == 0) { /* child */
+ int PauseMode = 1;
+
+ while (PauseMode)
+ sleep(10); /* Wait until someone attaches to us */
+ <lineannotation>&hellip</lineannotation>
+} else { /* parent */
+ <lineannotation>&hellip</lineannotation>
+ </screen>
+
+ <para>Now all you have to do is attach to the child, set
+ <symbol>PauseMode</symbol> to <literal>0</literal>, and wait
+ for the <function>sleep()</function> call to return!</para>
+ </sect2>
+ </sect1>
+
+ <sect1 id="emacs">
+ <title>Using Emacs as a Development Environment</title>
+
+ <sect2>
+ <title>Emacs</title>
+
+ <para>Unfortunately, Unix systems don't come with the kind of
+ everything-you-ever-wanted-and-lots-more-you-didn't-in-one-gigantic-package
+ integrated development environments that other systems
+ have.
+
+ <footnote>
+ <para>At least, not unless you pay out very large sums of
+ money.</para>
+ </footnote>
+
+ However, it is possible to set up your own environment. It
+ may not be as pretty, and it may not be quite as integrated,
+ but you can set it up the way you want it. And it's free.
+ And you have the source to it.</para>
+
+ <para>The key to it all is Emacs. Now there are some people who
+ loathe it, but many who love it. If you're one of the former,
+ I'm afraid this section will hold little of interest to you.
+ Also, you'll need a fair amount of memory to run it&mdash;I'd
+ recommend 8MB in text mode and 16MB in X as the bare minimum
+ to get reasonable performance.</para>
+
+ <para>Emacs is basically a highly customisable
+ editor&mdash;indeed, it has been customised to the point where
+ it's more like an operating system than an editor! Many
+ developers and sysadmins do in fact spend practically all
+ their time working inside Emacs, leaving it only to log
+ out.</para>
+
+ <para>It's impossible even to summarise everything Emacs can do
+ here, but here are some of the features of interest to
+ developers:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Very powerful editor, allowing search-and-replace on
+ both strings and regular expressions (patterns), jumping
+ to start/end of block expression, etc, etc.</para>
+ </listitem>
+
+ <listitem>
+ <para>Pull-down menus and online help.</para>
+ </listitem>
+
+ <listitem>
+ <para>Language-dependent syntax highlighting and
+ indentation.</para>
+ </listitem>
+
+ <listitem>
+ <para>Completely customisable.</para>
+ </listitem>
+
+ <listitem>
+ <para>You can compile and debug programs within
+ Emacs.</para>
+ </listitem>
+
+ <listitem>
+ <para>On a compilation error, you can jump to the offending
+ line of source code.</para>
+ </listitem>
+
+ <listitem>
+ <para>Friendly-ish front-end to the <command>info</command>
+ program used for reading GNU hypertext documentation,
+ including the documentation on Emacs itself.</para>
+ </listitem>
+
+ <listitem>
+ <para>Friendly front-end to <command>gdb</command>, allowing
+ you to look at the source code as you step through your
+ program.</para>
+ </listitem>
+
+ <listitem>
+ <para>You can read Usenet news and mail while your program
+ is compiling.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>And doubtless many more that I've overlooked.</para>
+
+ <para>Emacs can be installed on FreeBSD using <ulink
+ URL="../../ports/editors.html">the Emacs
+ port</ulink>.</para>
+
+ <para>Once it's installed, start it up and do <userinput>C-h
+ t</userinput> to read an Emacs tutorial&mdash;that means
+ hold down the <keycap>control</keycap> key, press
+ <keycap>h</keycap>, let go of the <keycap>control</keycap>
+ key, and then press <keycap>t</keycap>. (Alternatively, you
+ can you use the mouse to select <guimenuitem>Emacs
+ Tutorial</guimenuitem> from the <guimenu>Help</guimenu>
+ menu).</para>
+
+ <para>Although Emacs does have menus, it's well worth learning
+ the key bindings, as it's much quicker when you're editing
+ something to press a couple of keys than to try and find the
+ mouse and then click on the right place. And, when you're
+ talking to seasoned Emacs users, you'll find they often
+ casually throw around expressions like <quote><literal>M-x
+ replace-s RET foo RET bar RET</literal></quote> so it's
+ useful to know what they mean. And in any case, Emacs has far
+ too many useful functions for them to all fit on the menu
+ bars.</para>
+
+ <para>Fortunately, it's quite easy to pick up the key-bindings,
+ as they're displayed next to the menu item. My advice is to
+ use the menu item for, say, opening a file until you
+ understand how it works and feel confident with it, then try
+ doing C-x C-f. When you're happy with that, move on to
+ another menu command.</para>
+
+ <para>If you can't remember what a particular combination of
+ keys does, select <guimenuitem>Describe Key</guimenuitem> from
+ the <guimenu>Help</guimenu> menu and type it in&mdash;Emacs
+ will tell you what it does. You can also use the
+ <guimenuitem>Command Apropos</guimenuitem> menu item to find
+ out all the commands which contain a particular word in them,
+ with the key binding next to it.</para>
+
+ <para>By the way, the expression above means hold down the
+ <keysym>Meta</keysym> key, press <keysym>x</keysym>, release
+ the <keysym>Meta</keysym> key, type
+ <userinput>replace-s</userinput> (short for
+ <literal>replace-string</literal>&mdash;another feature of
+ Emacs is that you can abbreviate commands), press the
+ <keysym>return</keysym> key, type <userinput>foo</userinput>
+ (the string you want replaced), press the
+ <keysym>return</keysym> key, type bar (the string you want to
+ replace <literal>foo</literal> with) and press
+ <keysym>return</keysym> again. Emacs will then do the
+ search-and-replace operation you've just requested.</para>
+
+ <para>If you're wondering what on earth the
+ <keysym>Meta</keysym> key is, it's a special key that many
+ Unix workstations have. Unfortunately, PC's don't have one,
+ so it's usually the <keycap>alt</keycap> key (or if you're
+ unlucky, the <keysym>escape</keysym> key).</para>
+
+ <para>Oh, and to get out of Emacs, do <command>C-x C-c</command>
+ (that means hold down the <keysym>control</keysym> key, press
+ <keysym>x</keysym>, press <keysym>c</keysym> and release the
+ <keysym>control</keysym> key). If you have any unsaved files
+ open, Emacs will ask you if you want to save them. (Ignore
+ the bit in the documentation where it says
+ <command>C-z</command> is the usual way to leave
+ Emacs&mdash;that leaves Emacs hanging around in the
+ background, and is only really useful if you're on a system
+ which doesn't have virtual terminals).</para>
+ </sect2>
+
+ <sect2>
+ <title>Configuring Emacs</title>
+
+ <para>Emacs does many wonderful things; some of them are built
+ in, some of them need to be configured.</para>
+
+ <para>Instead of using a proprietary macro language for
+ configuration, Emacs uses a version of Lisp specially adapted
+ for editors, known as Emacs Lisp. This can be quite useful if
+ you want to go on and learn something like Common Lisp, as
+ it's considerably smaller than Common Lisp (although still
+ quite big!).</para>
+
+ <para>The best way to learn Emacs Lisp is to download the <ulink
+ URL="ftp://prep.ai.mit.edu:pub/gnu/elisp-manual-19-2.4.tar.gz">Emacs
+ Tutorial</ulink></para>
+
+ <para>However, there's no need to actually know any Lisp to get
+ started with configuring Emacs, as I've included a sample
+ <filename>.emacs</filename> file, which should be enough to
+ get you started. Just copy it into your home directory and
+ restart Emacs if it's already running; it will read the
+ commands from the file and (hopefully) give you a useful basic
+ setup.</para>
+ </sect2>
+
+ <sect2>
+ <title>A sample <filename>.emacs</filename> file</title>
+
+ <para>Unfortunately, there's far too much here to explain it in
+ detail; however there are one or two points worth
+ mentioning.</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Everything beginning with a <literal>;</literal> is a comment
+ and is ignored by Emacs.</para>
+ </listitem>
+
+ <listitem>
+ <para>In the first line, the
+ <literal>-*-&nbsp;Emacs-Lisp&nbsp;-*-</literal> is so that
+ we can edit the <filename>.emacs</filename> file itself
+ within Emacs and get all the fancy features for editing
+ Emacs Lisp. Emacs usually tries to guess this based on
+ the filename, and may not get it right for
+ <filename>.emacs</filename>.</para>
+ </listitem>
+
+ <listitem>
+ <para>The <keysym>tab</keysym> key is bound to an
+ indentation function in some modes, so when you press the
+ tab key, it will indent the current line of code. If you
+ want to put a <token>tab</token> character in whatever
+ you're writing, hold the <keysym>control</keysym> key down
+ while you're pressing the <keysym>tab</keysym> key.</para>
+ </listitem>
+
+ <listitem>
+ <para>This file supports syntax highlighting for C, C++,
+ Perl, Lisp and Scheme, by guessing the language from the
+ filename.</para>
+ </listitem>
+
+ <listitem>
+ <para>Emacs already has a pre-defined function called
+ <function>next-error</function>. In a compilation output
+ window, this allows you to move from one compilation error
+ to the next by doing <command>M-n</command>; we define a
+ complementary function,
+ <function>previous-error</function>, that allows you to go
+ to a previous error by doing <command>M-p</command>. The
+ nicest feature of all is that <command>C-c C-c</command>
+ will open up the source file in which the error occurred
+ and jump to the appropriate line.</para>
+ </listitem>
+
+ <listitem>
+ <para>We enable Emacs's ability to act as a server, so that
+ if you're doing something outside Emacs and you want to
+ edit a file, you can just type in</para>
+
+ <screen>&prompt.user; <userinput>emacsclient <replaceable>filename</replaceable></userinput>
+ </screen>
+
+ <para>and then you can edit the file in your
+ Emacs!
+
+ <footnote>
+ <para>Many Emacs users set their <systemitem
+ class=environvar>EDITOR</systemitem> environment to
+ <literal>emacsclient</literal> so this happens every
+ time they need to edit a file.</para>
+ </footnote></para>
+ </listitem>
+ </itemizedlist>
+
+ <example>
+ <title>A sample <filename>.emacs</filename> file</title>
+
+ <programlisting>;; -*-Emacs-Lisp-*-
+
+;; This file is designed to be re-evaled; use the variable first-time
+;; to avoid any problems with this.
+(defvar first-time t
+ "Flag signifying this is the first time that .emacs has been evaled")
+
+;; Meta
+(global-set-key "\M- " 'set-mark-command)
+(global-set-key "\M-\C-h" 'backward-kill-word)
+(global-set-key "\M-\C-r" 'query-replace)
+(global-set-key "\M-r" 'replace-string)
+(global-set-key "\M-g" 'goto-line)
+(global-set-key "\M-h" 'help-command)
+
+;; Function keys
+(global-set-key [f1] 'manual-entry)
+(global-set-key [f2] 'info)
+(global-set-key [f3] 'repeat-complex-command)
+(global-set-key [f4] 'advertised-undo)
+(global-set-key [f5] 'eval-current-buffer)
+(global-set-key [f6] 'buffer-menu)
+(global-set-key [f7] 'other-window)
+(global-set-key [f8] 'find-file)
+(global-set-key [f9] 'save-buffer)
+(global-set-key [f10] 'next-error)
+(global-set-key [f11] 'compile)
+(global-set-key [f12] 'grep)
+(global-set-key [C-f1] 'compile)
+(global-set-key [C-f2] 'grep)
+(global-set-key [C-f3] 'next-error)
+(global-set-key [C-f4] 'previous-error)
+(global-set-key [C-f5] 'display-faces)
+(global-set-key [C-f8] 'dired)
+(global-set-key [C-f10] 'kill-compilation)
+
+;; Keypad bindings
+(global-set-key [up] "\C-p")
+(global-set-key [down] "\C-n")
+(global-set-key [left] "\C-b")
+(global-set-key [right] "\C-f")
+(global-set-key [home] "\C-a")
+(global-set-key [end] "\C-e")
+(global-set-key [prior] "\M-v")
+(global-set-key [next] "\C-v")
+(global-set-key [C-up] "\M-\C-b")
+(global-set-key [C-down] "\M-\C-f")
+(global-set-key [C-left] "\M-b")
+(global-set-key [C-right] "\M-f")
+(global-set-key [C-home] "\M-&lt;")
+(global-set-key [C-end] "\M-&gt;")
+(global-set-key [C-prior] "\M-&lt;")
+(global-set-key [C-next] "\M-&gt;")
+
+;; Mouse
+(global-set-key [mouse-3] 'imenu)
+
+;; Misc
+(global-set-key [C-tab] "\C-q\t") ; Control tab quotes a tab.
+(setq backup-by-copying-when-mismatch t)
+
+;; Treat 'y' or &lt;CR&gt; as yes, 'n' as no.
+(fset 'yes-or-no-p 'y-or-n-p)
+ (define-key query-replace-map [return] 'act)
+ (define-key query-replace-map [?\C-m] 'act)
+
+;; Load packages
+(require 'desktop)
+(require 'tar-mode)
+
+;; Pretty diff mode
+(autoload 'ediff-buffers "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files-remote "ediff"
+ "Intelligent Emacs interface to diff")
+
+(if first-time
+ (setq auto-mode-alist
+ (append '(("\\.cpp$" . c++-mode)
+ ("\\.hpp$" . c++-mode)
+ ("\\.lsp$" . lisp-mode)
+ ("\\.scm$" . scheme-mode)
+ ("\\.pl$" . perl-mode)
+ ) auto-mode-alist)))
+
+;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+(defvar font-lock-mode-keyword-alist
+ '((c++-c-mode . c-font-lock-keywords)
+ (perl-mode . perl-font-lock-keywords))
+ "Associations between modes and keywords")
+
+(defun font-lock-auto-mode-select ()
+ "Automatically select font-lock-mode if the current major mode is
+in font-lock-auto-mode-list"
+ (if (memq major-mode font-lock-auto-mode-list)
+ (progn
+ (font-lock-mode t))
+ )
+ )
+
+(global-set-key [M-f1] 'font-lock-fontify-buffer)
+
+;; New dabbrev stuff
+;(require 'new-dabbrev)
+(setq dabbrev-always-check-other-buffers t)
+(setq dabbrev-abbrev-char-regexp "\\sw\\|\\s_")
+(add-hook 'emacs-lisp-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'c-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'text-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) t)
+ (set (make-local-variable 'dabbrev-case-replace) t)))
+
+;; C++ and C mode...
+(defun my-c++-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c++-mode-map "\C-ce" 'c-comment-edit)
+ (setq c++-auto-hungry-initial-state 'none)
+ (setq c++-delete-function 'backward-delete-char)
+ (setq c++-tab-always-indent t)
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c++-empty-arglist-indent 4))
+
+(defun my-c-mode-hook ()
+ (setq tab-width 4)
+ (define-key c-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c-mode-map "\C-ce" 'c-comment-edit)
+ (setq c-auto-hungry-initial-state 'none)
+ (setq c-delete-function 'backward-delete-char)
+ (setq c-tab-always-indent t)
+;; BSD-ish indentation style
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c-brace-offset -4)
+ (setq c-argdecl-indent 0)
+ (setq c-label-offset -4))
+
+;; Perl mode
+(defun my-perl-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (setq perl-indent-level 4)
+ (setq perl-continued-statement-offset 4))
+
+;; Scheme mode...
+(defun my-scheme-mode-hook ()
+ (define-key scheme-mode-map "\C-m" 'reindent-then-newline-and-indent))
+
+;; Emacs-Lisp mode...
+(defun my-lisp-mode-hook ()
+ (define-key lisp-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key lisp-mode-map "\C-i" 'lisp-indent-line)
+ (define-key lisp-mode-map "\C-j" 'eval-print-last-sexp))
+
+;; Add all of the hooks...
+(add-hook 'c++-mode-hook 'my-c++-mode-hook)
+(add-hook 'c-mode-hook 'my-c-mode-hook)
+(add-hook 'scheme-mode-hook 'my-scheme-mode-hook)
+(add-hook 'emacs-lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'perl-mode-hook 'my-perl-mode-hook)
+
+;; Complement to next-error
+(defun previous-error (n)
+ "Visit previous compilation error message and corresponding source code."
+ (interactive "p")
+ (next-error (- n)))
+
+;; Misc...
+(transient-mark-mode 1)
+(setq mark-even-if-inactive t)
+(setq visible-bell nil)
+(setq next-line-add-newlines nil)
+(setq compile-command "make")
+(setq suggest-key-bindings nil)
+(put 'eval-expression 'disabled nil)
+(put 'narrow-to-region 'disabled nil)
+(put 'set-goal-column 'disabled nil)
+
+;; Elisp archive searching
+(autoload 'format-lisp-code-directory "lispdir" nil t)
+(autoload 'lisp-dir-apropos "lispdir" nil t)
+(autoload 'lisp-dir-retrieve "lispdir" nil t)
+(autoload 'lisp-dir-verify "lispdir" nil t)
+
+;; Font lock mode
+(defun my-make-face (face colour &amp;optional bold)
+ "Create a face from a colour and optionally make it bold"
+ (make-face face)
+ (copy-face 'default face)
+ (set-face-foreground face colour)
+ (if bold (make-face-bold face))
+ )
+
+(if (eq window-system 'x)
+ (progn
+ (my-make-face 'blue "blue")
+ (my-make-face 'red "red")
+ (my-make-face 'green "dark green")
+ (setq font-lock-comment-face 'blue)
+ (setq font-lock-string-face 'bold)
+ (setq font-lock-type-face 'bold)
+ (setq font-lock-keyword-face 'bold)
+ (setq font-lock-function-name-face 'red)
+ (setq font-lock-doc-string-face 'green)
+ (add-hook 'find-file-hooks 'font-lock-auto-mode-select)
+
+ (setq baud-rate 1000000)
+ (global-set-key "\C-cmm" 'menu-bar-mode)
+ (global-set-key "\C-cms" 'scroll-bar-mode)
+ (global-set-key [backspace] 'backward-delete-char)
+ ; (global-set-key [delete] 'delete-char)
+ (standard-display-european t)
+ (load-library "iso-transl")))
+
+;; X11 or PC using direct screen writes
+(if window-system
+ (progn
+ ;; (global-set-key [M-f1] 'hilit-repaint-command)
+ ;; (global-set-key [M-f2] [?\C-u M-f1])
+ (setq hilit-mode-enable-list
+ '(not text-mode c-mode c++-mode emacs-lisp-mode lisp-mode
+ scheme-mode)
+ hilit-auto-highlight nil
+ hilit-auto-rehighlight 'visible
+ hilit-inhibit-hooks nil
+ hilit-inhibit-rebinding t)
+ (require 'hilit19)
+ (require 'paren))
+ (setq baud-rate 2400) ; For slow serial connections
+ )
+
+;; TTY type terminal
+(if (and (not window-system)
+ (not (equal system-type 'ms-dos)))
+ (progn
+ (if first-time
+ (progn
+ (keyboard-translate ?\C-h ?\C-?)
+ (keyboard-translate ?\C-? ?\C-h)))))
+
+;; Under UNIX
+(if (not (equal system-type 'ms-dos))
+ (progn
+ (if first-time
+ (server-start))))
+
+;; Add any face changes here
+(add-hook 'term-setup-hook 'my-term-setup-hook)
+(defun my-term-setup-hook ()
+ (if (eq window-system 'pc)
+ (progn
+;; (set-face-background 'default "red")
+ )))
+
+;; Restore the "desktop" - do this as late as possible
+(if first-time
+ (progn
+ (desktop-load-default)
+ (desktop-read)))
+
+;; Indicate that this file has been read at least once
+(setq first-time nil)
+
+;; No need to debug anything now
+(setq debug-on-error nil)
+
+;; All done
+(message "All done, %s%s" (user-login-name) ".")
+ </programlisting>
+ </example>
+ </sect2>
+
+ <sect2>
+ <title>Extending the Range of Languages Emacs Understands</title>
+
+ <para>Now, this is all very well if you only want to program in
+ the languages already catered for in the
+ <filename>.emacs</filename> file (C, C++, Perl, Lisp and
+ Scheme), but what happens if a new language called
+ <quote>whizbang</quote> comes out, full of exciting
+ features?</para>
+
+ <para>The first thing to do is find out if whizbang comes with
+ any files that tell Emacs about the language. These usually
+ end in <filename>.el</filename>, short for <quote>Emacs
+ Lisp</quote>. For example, if whizbang is a FreeBSD port, we
+ can locate these files by doing</para>
+
+ <screen>&prompt.user; <userinput>find /usr/ports/lang/whizbang -name "*.el" -print</userinput>
+ </screen>
+
+ <para>and install them by copying them into the Emacs site Lisp
+ directory. On FreeBSD 2.1.0-RELEASE, this is
+ <filename>/usr/local/share/emacs/site-lisp</filename>.</para>
+
+ <para>So for example, if the output from the find command
+ was</para>
+
+ <screen>/usr/ports/lang/whizbang/work/misc/whizbang.el
+ </screen>
+
+ <para>we would do</para>
+
+ <screen>&prompt.root; <userinput>cp /usr/ports/lang/whizbang/work/misc/whizbang.el /usr/local/share/emacs/site-lisp</userinput>
+ </screen>
+
+ <para>Next, we need to decide what extension whizbang source
+ files have. Let's say for the sake of argument that they all
+ end in <filename>.wiz</filename>. We need to add an entry to
+ our <filename>.emacs</filename> file to make sure Emacs will
+ be able to use the information in
+ <filename>whizbang.el</filename>.</para>
+
+ <para>Find the <symbol>auto-mode-alist entry</symbol> in
+ <filename>.emacs</filename> and add a line for whizbang, such
+ as:</para>
+
+ <programlisting><lineannotation>&hellip;</>
+("\\.lsp$" . lisp-mode)
+("\\.wiz$" . whizbang-mode)
+("\\.scm$" . scheme-mode)
+<lineannotation>&hellip;</>
+ </programlisting>
+
+ <para>This means that Emacs will automatically go into
+ <function>whizbang-mode</function> when you edit a file ending
+ in <filename>.wiz</filename>.</para>
+
+ <para>Just below this, you'll find the
+ <symbol>font-lock-auto-mode-list</symbol> entry. Add
+ <function>whizbang-mode</function> to it like so:</para>
+
+ <programlisting>;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'whizbang-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+ </programlisting>
+
+ <para>This means that Emacs will always enable
+ <function>font-lock-mode</function> (ie syntax highlighting)
+ when editing a <filename>.wiz</filename> file.</para>
+
+ <para>And that's all that's needed. If there's anything else
+ you want done automatically when you open up a
+ <filename>.wiz</filename> file, you can add a
+ <function>whizbang-mode hook</function> (see
+ <function>my-scheme-mode-hook</function> for a simple example
+ that adds <function>auto-indent</function>).</para>
+ </sect2>
+ </sect1>
+
+ <sect1>
+ <title>Further Reading</title>
+
+ <itemizedlist>
+ <listitem>
+ <para>Brian Harvey and Matthew Wright
+ <emphasis>Simply Scheme</emphasis>
+ MIT 1994.<!-- <br> -->
+ ISBN 0-262-08226-8</para>
+ </listitem>
+
+ <listitem>
+ <para>Randall Schwartz
+ <emphasis>Learning Perl</emphasis>
+ O'Reilly 1993<!-- <br> -->
+ ISBN 1-56592-042-2</para>
+ </listitem>
+
+ <listitem>
+ <para>Patrick Henry Winston and Berthold Klaus Paul Horn
+ <emphasis>Lisp (3rd Edition)</emphasis>
+ Addison-Wesley 1989<!-- <br> -->
+ ISBN 0-201-08319-1</para>
+ </listitem>
+
+ <listitem>
+ <para>Brian W. Kernighan and Rob Pike
+ <emphasis>The Unix Programming Environment</emphasis>
+ Prentice-Hall 1984<!-- <br> -->
+ ISBN 0-13-937681-X</para>
+ </listitem>
+
+ <listitem>
+ <para>Brian W. Kernighan and Dennis M. Ritchie
+ <emphasis>The C Programming Language (2nd Edition)</emphasis>
+ Prentice-Hall 1988<!-- <br> -->
+ ISBN 0-13-110362-8</para>
+ </listitem>
+
+ <listitem>
+ <para>Bjarne Stroustrup
+ <emphasis>The C++ Programming Language</emphasis>
+ Addison-Wesley 1991<!-- <br> -->
+ ISBN 0-201-53992-6</para>
+ </listitem>
+
+ <listitem>
+ <para>W. Richard Stevens
+ <emphasis>Advanced Programming in the Unix Environment</emphasis>
+ Addison-Wesley 1992<!-- <br> -->
+ ISBN 0-201-56317-7</para>
+ </listitem>
+
+ <listitem>
+ <para>W. Richard Stevens
+ <emphasis>Unix Network Programming</emphasis>
+ Prentice-Hall 1990<!-- <br> -->
+ ISBN 0-13-949876-1</para>
+ </listitem>
+ </itemizedlist>
+ </sect1>
- <para></para>
</chapter>
<chapter id="secure-programming">
@@ -1357,7 +3598,7 @@ DRIVER_MODULE(mypci, pci, mypci_driver, mypci_devclass, 0, 0);
</chapter>
</part>
- <part id="debugging">
+ <part id="debuggingpart">
<title>Debugging</title>
<chapter id="truss">