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- Committer: Kevin Cole
- Date: 2005-12-22 00:40:58 UTC
- Revision ID: kjcole@gri.gallaudet.edu-20051222004058-f53cb6abfc942af7
Making a few files validate against lore
added
removed
lore/glossary.lore
5
5
6
6
<body>
7
7
<h1>Glossary</h1>
8
</p>
9
10
<p>Asymmetric Digital Subscriber Line ( ADSL)
11
ADSL is a technology for transmitting digital data
12
across normal copper phone lines at high speeds. It is
13
a short-range technology, requiring subscribers to be
14
within a few kilometres of the exchange providing the
15
service. It is called Asymmetric because download
16
speeds are configured to be far higher than upload
17
speeds (you can receive more quickly than you can
18
send).
19
</p>
20
21
<p>Application Programming Interface (API)
22
Just as a program has a range of menus, icons and
23
buttons with which a user can control it, it can have a
24
set of method calls and data structures that can be
25
used by other programs to control it. This is the API.
26
</p>
27
28
<p>Basic In/Out System ( BIOS)
29
A small program in non-volatile storage that is
30
executed immediately after a computer is powered up.
31
Normally, it passes control to the boot loader of the
32
selected boot media as soon as possible. However, it
33
also displays some diagnostic information while
34
executing, including a prompt to enter configuration
35
mode. While in configuration mode, you may set various
36
basic properties of the computer, such as the time of
37
the system clock and the selected boot media (e.g.
38
CD-ROM, hard disk, or network).
39
</p>
40
41
<p>boot
42
When a computer is powered up, control immediately
43
passes to the BIOS. The BIOS finds the program code
44
that should be executed to continue the startup
45
process, until the operating system is up and running.
46
The whole procedure is called booting up, from the
47
expression "pulling yourself up by your bootlaces".
48
Picture a cartoon figure on flat land, grabbing hold of
49
his bootlaces and pulling himself up into the air until
50
he's flying. A computer manages something similar, when
51
it changes from an inert lump of plastic to a running
52
system.
53
</p>
54
55
<p>Central Processing Unit ( CPU)
56
The CPU is the core of the computer. It's one of the
57
smaller pieces, consisting of a flat square of silicon,
58
but it contains most of the computer's complexity, in
59
the form of millions of transistors. When the computer
60
is executing programs, all of the instructions as well
61
as the data are fetched from RAM and processed by the
62
CPU.
63
</p>
64
65
<p>Common Gateway Interface (CGI)
66
This is a specification for calling scripts that are
67
triggered through the web. The CGI standard specifies
68
what data must be passed to the script.
69
</p>
70
71
<p>daemon
72
A program that runs on a server, waiting for requests
73
and servicing them. The program runs permanently, as
74
long as the service should be offered.
75
</p>
76
77
<p>Document Object Model ( DOM)
78
When a web browser parses an HTML page, it doesn't just
79
write out text to the screen and have done with it. It
80
needs to hold on to the entire structure in order to be
81
able to rewrite it using Javascript, changing parts of
82
the page in-place and reflowing the resulting document
83
immediately. This internal structure is called the
84
Document Object Model. You can read all about it at the
85
World Wide Web Consortium's Document Object Model page.
86
</p>
87
88
<p>Domain Name System ( DNS)
89
The Domain Name System is part of the core
90
infrastructure of the internet. It consists of a
91
massive globally distributed database that matches IP
92
addresses (e.g. 216.239.57.99) to domain names that
93
humans like to remember (e.g. google.com). As long as
94
they keep to the rules, anyone can run a DNS server to
95
resolve local address and to cache global addresses. No
96
DNS server needs to store all the domain names on
97
earth: the job is distributed among ISPs who each take
98
responsibility for different sections of the namespace.
99
If your local nameserver doesn't know an IP address, it
100
knows who to ask to get an answer.
101
</p>
102
103
<p>If DNS is unavailable, all the services that depend on
104
it (such as web browsing and email) don't work.
105
</p>
106
107
<p>Dynamic Host Configuration Protocol ( DHCP)
108
See Section 9.2.
109
</p>
110
111
<p>Etherboot
112
See PXE in Section 16.4.
113
</p>
114
115
<p>Internet Service Provider ( ISP)
116
A business which provides internet access to its
117
customers. The nature of this service may vary widely,
118
from dialup access and email for home users to wireless
119
broadband and website hosting for big media companies
120
and everything in between.
121
</p>
122
123
<p>platform independence
124
A platform is a short name for the entire software
125
environment which a specific program requires in order
126
to run. Programs may target an operating system (the
127
Windows, Linux or Macintosh platforms), or a virtual
128
machine (the Java platform, which is available across
129
operating systems). Increasingly, web applications such
130
as Google's Gmail email service target the web browser
131
as platform.
132
</p>
133
134
<p>When a program is capable of being run on many
135
different platforms, it is called cross-platform. In
136
this case, it either needs to be rather self-contained,
137
not making use of any special capabilities of any
138
specific platform, or it needs to contain alternative
139
implementations for all the platforms it caters for.
140
</p>
141
142
<p>Power On Self Test ( POST)
143
The POST is a series of hardcoded self-tests that a
144
computer's BIOS performs to see whether basic resources
145
such as its CPU, memory, and keyboard are present and
146
functional.
147
</p>
148
149
<p>Pre-boot eXecution Environment ( PXE)
150
A small program on the network card that allows a
151
computer to boot from the network. The PXE takes care
152
of finding a server from which to boot, and
153
transferring the boot loader from the server to the
154
client across the network.
155
</p>
156
157
<p>Programmable ROM ( PROM)
158
This is a kind of memory that can be written exactly
159
once. After it's been written, its contents is fixed.
160
It's generally used for things like network cards with
161
the facility to boot from the network. Such cards can
162
be used in many different environments, requiring
163
different software. However, once deployed in some
164
environment, it normally stays there. Therefor the
165
required software can be written to a PROM on the card,
166
effectively locking down the card to the deployed
167
environment.
168
</p>
169
170
<p>Media Access Control address ( MAC address)
171
In computer networking, a MAC address is a code on most
172
forms of networking equipment that allows for that
173
device to be uniquely identified.
174
</p>
175
176
<p>Network File System ( NFS)
177
A local filesystem reads data from a hard disk. NFS is
178
a protocol that allows a remote filesystem to be
179
mounted on a path of the local filesystem, so that data
180
read from files on that path is not read from a local
181
disk, but from a server on the network.
182
</p>
183
184
<p>netmask
185
In Section 8.4 networking, the netmask specifies all
186
the IP addresses that belong to a particular network.
187
</p>
188
189
<p>RAM disk
190
A physical hard disk stores data on magnetic platters.
191
A RAM disk emulates a hard disk using the computer's
192
memory. Whereas a hard disk stores data permanently
193
until it is rewritten, a RAM disk only exists as a
194
running program, and goes away when the program stops
195
or the computer is powered down.
196
</p>
197
198
<p>Random Access Memory ( RAM)
199
Memory that stores code and data only as long as the
200
computer is powered up. At the first hint of a power
201
interruption, RAM becomes as blank as a beach washed
202
clean by the tide. RAM can be written to, and during
203
execution, programs are continuously rewriting its
204
contents.
205
</p>
206
207
<p>Read Only Memory ( ROM)
208
Memory that stores code and data permanently, whether
209
or not the workstation is powered up. It cannot be
210
written to: every time it's read, it's exactly the
211
same.
212
</p>
213
214
<p>Read the FINE Manual ( RTFM)
215
Linux is a self-documenting system. All Linux programs
216
come with technical documentation, and most commands
217
accept a --help option that will start you off. The
218
information is sometimes cryptic, or just very dense,
219
but if you don't read it two, three, four or five
220
times, you'll find yourself asking the same questions
221
again and again, and never progressing beyond the
222
basics.
223
</p>
224
225
<p>You'll also find that people answer your questions with
226
a terse " RTFM!", meaning that the answer is right
227
there in the manual. Don't take offence, look it up.
228
</p>
229
230
<p>root
231
Linux systems loosely use a tree metaphor to explain
232
some aspects of their structure. So, for example, the
233
user who is the system administrator, with all
234
privileges to make or break the system, is the root
235
user. The root user can create other users and groups
236
with more limited privileges, like the branches of a
237
tree that are separate and thinner than the trunk.
238
</p>
239
240
<p>root filesystem
241
The filesystem is an hierarchical tree structure. The
242
directory which contains all the others is called the
243
root, and is written like this: /. This is a
244
subdirectory of the root directory: /etc. This is a
245
file in that subdirectory: /etc/hosts.
246
</p>
247
248
<p>shell
249
Another metaphor used to express the structure of a
250
Linux system is that of a nut containing a kernel. The
251
kernel is hidden inside, it is surrounded by a shell.
252
As user you can't interact with the kernel directly,
253
you interact with a shell program. This is a program
254
which accepts commands and gives feedback, all via a
255
textual command line interface. The shell has a number
256
of builtin commands, but it also does job control,
257
starting and stopping programs that run under its
258
control.
259
</p>
260
261
<p>The shell has a full complement of flow control
262
structures, so that it can be used to write programs.
263
These are called shell scripts. Shell scripts are most
264
often used to coordinate the execution of other
265
programs.
266
</p>
267
268
<p>Simple Mail Transfer Protocol ( SMTP)
269
When you send an email, your mail server looks at the
270
headers of the mail to see where it should be
271
delivered. It then uses DNS to look up the IP address
272
of the mail server on the receiving end. When it knows
273
whom to contact, it starts an SMTP conversation with
274
the remote mailserver. It asks the server what version
275
of the protocol it supports (so that it knows how to
276
encode the mail, if necessary) and whether the server
277
is accepting mail for the user you want to reach. When
278
the two servers have gotten to know one another, the
279
mail is transferred and queued for the remote user to
280
read.
281
</p>
282
283
<p>symbolic links
284
A file can only be stored in one place on a disk. If
285
you want it to appear to be in other places as well,
286
you can make a symbolic link from there to the real
287
location of the file. By most commands, the link will
288
be transparent: it will be treated exactly as though
289
the file really exists in that location.
290
_________________________________________________________
8
9
<dl>
10
<dt><b>Asymmetric Digital Subscriber Line (ADSL)</b></dt>
11
<dd>ADSL is a technology for transmitting digital data across normal
12
copper phone lines at high speeds. It is a short-range technology,
13
requiring subscribers to be within a few kilometres of the exchange
14
providing the service. It is called Asymmetric because download
15
speeds are configured to be far higher than upload speeds (you can
16
receive more quickly than you can send).</dd>
17
18
<dt><b>Application Programming Interface (API)</b></dt>
19
<dd>Just as a program has a range of menus, icons and buttons with
20
which a user can control it, it can have a set of method calls and
21
data structures that can be used by other programs to control
22
it. This is the API.</dd>
23
24
<dt><b>Basic In/Out System (BIOS)</b></dt>
25
<dd>A small program in non-volatile storage that is executed
26
immediately after a computer is powered up. Normally, it passes
27
control to the boot loader of the selected boot media as soon as
28
possible. However, it also displays some diagnostic information
29
while executing, including a prompt to enter configuration
30
mode. While in configuration mode, you may set various basic
31
properties of the computer, such as the time of the system clock and
32
the selected boot media (e.g. CD-ROM, hard disk, or network).</dd>
33
34
<dt><b>boot</b></dt>
35
<dd>When a computer is powered up, control immediately passes to the
36
BIOS. The BIOS finds the program code that should be executed to
37
continue the startup process, until the operating system is up and
38
running. The whole procedure is called booting up, from the
39
expression "pulling yourself up by your bootlaces". Picture a
40
cartoon figure on flat land, grabbing hold of his bootlaces and
41
pulling himself up into the air until he's flying. A computer
42
manages something similar, when it changes from an inert lump of
43
plastic to a running system.</dd>
44
45
<dt><b>Central Processing Unit (CPU)</b></dt>
46
<dd>The CPU is the core of the computer. It's one of the smaller
47
pieces, consisting of a flat square of silicon, but it contains most
48
of the computer's complexity, in the form of millions of
49
transistors. When the computer is executing programs, all of the
50
instructions as well as the data are fetched from RAM and processed
51
by the CPU.</dd>
52
53
<dt><b>Common Gateway Interface (CGI)</b></dt>
54
<dd>This is a specification for calling scripts that are triggered
55
through the web. The CGI standard specifies what data must be passed
56
to the script.</dd>
57
58
<dt><b>daemon</b></dt>
59
<dd>A program that runs on a server, waiting for requests and
60
servicing them. The program runs permanently, as long as the service
61
should be offered.</dd>
62
63
<dt><b>Document Object Model (DOM)</b></dt>
64
<dd>When a web browser parses an HTML page, it doesn't just write
65
out text to the screen and have done with it. It needs to hold on to
66
the entire structure in order to be able to rewrite it using
67
Javascript, changing parts of the page in-place and reflowing the
68
resulting document immediately. This internal structure is called
69
the Document Object Model. You can read all about it at the World
70
Wide Web Consortium's Document Object Model page.</dd>
71
72
<dt><b>Domain Name System (DNS)</b></dt>
73
<dd>The Domain Name System is part of the core infrastructure of the
74
internet. It consists of a massive globally distributed database
75
that matches IP addresses (e.g. 216.239.57.99) to domain names that
76
humans like to remember (e.g. google.com). As long as they keep to
77
the rules, anyone can run a DNS server to resolve local address and
78
to cache global addresses. No DNS server needs to store all the
79
domain names on earth: the job is distributed among ISPs who each
80
take responsibility for different sections of the namespace. If your
81
local nameserver doesn't know an IP address, it knows who to ask to
82
get an answer.
83
<br /><br />
84
If DNS is unavailable, all the services that depend on it (such as
85
web browsing and email) don't work.</dd>
86
87
<dt><b>Dynamic Host Configuration Protocol (DHCP)</b></dt>
88
<dd>See Section 9.2.</dd>
89
90
<dt><b>Etherboot</b></dt>
91
<dd>See PXE in Section 16.4.</dd>
92
93
<dt><b>Internet Service Provider (ISP)</b></dt>
94
<dd>A business which provides internet access to its customers. The
95
nature of this service may vary widely, from dialup access and email
96
for home users to wireless broadband and website hosting for big
97
media companies and everything in between.</dd>
98
99
<dt><b>platform independence</b></dt>
100
<dd>A platform is a short name for the entire software environment
101
which a specific program requires in order to run. Programs may
102
target an operating system (the Windows, Linux or Macintosh
103
platforms), or a virtual machine (the Java platform, which is
104
available across operating systems). Increasingly, web applications
105
such as Google's Gmail email service target the web browser as
106
platform.
107
<br /><br />
108
When a program is capable of being run on many different platforms,
109
it is called cross-platform. In this case, it either needs to be
110
rather self-contained, not making use of any special capabilities of
111
any specific platform, or it needs to contain alternative
112
implementations for all the platforms it caters for.</dd>
113
114
<dt><b>Power On Self Test (POST)</b></dt>
115
<dd>The POST is a series of hardcoded self-tests that a computer's
116
BIOS performs to see whether basic resources such as its CPU,
117
memory, and keyboard are present and functional.</dd>
118
119
<dt><b>Pre-boot eXecution Environment (PXE)</b></dt>
120
<dd>A small program on the network card that allows a computer to
121
boot from the network. The PXE takes care of finding a server from
122
which to boot, and transferring the boot loader from the server to
123
the client across the network.</dd>
124
125
<dt><b>Programmable ROM (PROM)</b></dt>
126
<dd>This is a kind of memory that can be written exactly once. After
127
it's been written, its contents is fixed. It's generally used for
128
things like network cards with the facility to boot from the
129
network. Such cards can be used in many different environments,
130
requiring different software. However, once deployed in some
131
environment, it normally stays there. Therefor the required software
132
can be written to a PROM on the card, effectively locking down the
133
card to the deployed environment.</dd>
134
135
<dt><b>Media Access Control address (MAC address)</b></dt>
136
<dd>In computer networking, a MAC address is a code on most forms of
137
networking equipment that allows for that device to be uniquely
138
identified.</dd>
139
140
<dt><b>Network File System (NFS)</b></dt>
141
<dd>A local filesystem reads data from a hard disk. NFS is a
142
protocol that allows a remote filesystem to be mounted on a path of
143
the local filesystem, so that data read from files on that path is
144
not read from a local disk, but from a server on the network.</dd>
145
146
<dt><b>netmask</b></dt>
147
<dd>In Section 8.4 networking, the netmask specifies all the IP
148
addresses that belong to a particular network.</dd>
149
150
<dt><b>RAM disk</b></dt>
151
<dd>A physical hard disk stores data on magnetic platters. A RAM
152
disk emulates a hard disk using the computer's memory. Whereas a
153
hard disk stores data permanently until it is rewritten, a RAM disk
154
only exists as a running program, and goes away when the program
155
stops or the computer is powered down.</dd>
156
157
<dt><b>Random Access Memory (RAM)</b></dt>
158
<dd>Memory that stores code and data only as long as the computer is
159
powered up. At the first hint of a power interruption, RAM becomes
160
as blank as a beach washed clean by the tide. RAM can be written to,
161
and during execution, programs are continuously rewriting its
162
contents.</dd>
163
164
<dt><b>Read Only Memory (ROM)</b></dt>
165
<dd>Memory that stores code and data permanently, whether or not the
166
workstation is powered up. It cannot be written to: every time it's
167
read, it's exactly the same.</dd>
168
169
<dt><b>Read the FINE Manual (RTFM)</b></dt>
170
<dd>Linux is a self-documenting system. All Linux programs come with
171
technical documentation, and most commands accept a --help option
172
that will start you off. The information is sometimes cryptic, or
173
just very dense, but if you don't read it two, three, four or five
174
times, you'll find yourself asking the same questions again and
175
again, and never progressing beyond the basics.
176
<br /><br />
177
You'll also find that people answer your questions with a terse "
178
RTFM!", meaning that the answer is right there in the manual. Don't
179
take offence, look it up.</dd>
180
181
<dt><b>root</b></dt>
182
<dd>Linux systems loosely use a tree metaphor to explain some
183
aspects of their structure. So, for example, the user who is the
184
system administrator, with all privileges to make or break the
185
system, is the root user. The root user can create other users and
186
groups with more limited privileges, like the branches of a tree
187
that are separate and thinner than the trunk.</dd>
188
189
<dt><b>root filesystem</b></dt>
190
<dd>The filesystem is an hierarchical tree structure. The directory
191
which contains all the others is called the root, and is written
192
like this: /. This is a subdirectory of the root directory:
193
/etc. This is a file in that subdirectory: /etc/hosts.</dd>
194
195
<dt><b>shell</b></dt>
196
<dd>Another metaphor used to express the structure of a Linux system
197
is that of a nut containing a kernel. The kernel is hidden inside,
198
it is surrounded by a shell. As user you can't interact with the
199
kernel directly, you interact with a shell program. This is a
200
program which accepts commands and gives feedback, all via a textual
201
command line interface. The shell has a number of builtin commands,
202
but it also does job control, starting and stopping programs that
203
run under its control.
204
<br /><br />
205
The shell has a full complement of flow control structures, so that
206
it can be used to write programs. These are called shell
207
scripts. Shell scripts are most often used to coordinate the
208
execution of other programs.</dd>
209
210
<dt><b>Simple Mail Transfer Protocol (SMTP)</b></dt>
211
<dd>When you send an email, your mail server looks at the headers of
212
the mail to see where it should be delivered. It then uses DNS to
213
look up the IP address of the mail server on the receiving end. When
214
it knows whom to contact, it starts an SMTP conversation with the
215
remote mailserver. It asks the server what version of the protocol
216
it supports (so that it knows how to encode the mail, if necessary)
217
and whether the server is accepting mail for the user you want to
218
reach. When the two servers have gotten to know one another, the
219
mail is transferred and queued for the remote user to read.</dd>
220
221
<dt><b>symbolic links</b></dt>
222
<dd>A file can only be stored in one place on a disk. If you want it
223
to appear to be in other places as well, you can make a symbolic
224
link from there to the real location of the file. By most commands,
225
the link will be transparent: it will be treated exactly as though
226
the file really exists in that location.</dd>
227
</dl>
291
228
292
229
</body>
293
230
</html>
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