Book Home

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Index: U

unbuffering output stream: 15.2.6. Unbuffer Output Stream

undef vs. (): 17.1.5. undef Versus ( )

underscores (_)

filenames, replacing characters with: 5.2.4. File Uploads with CGI.pm
nonalphanumeric parameter name characters, replacing with: 5.2.3. Exporting Parameters to a Namespace
use in Perl: 16.2. Coding Guidelines

Unicode-compliant data transport, XML: 14.2. An Introduction to XML

unique identifiers

generating for sessions: 11.2. Hidden Fields
in hidden field: 11.2. Hidden Fields
inserting into HTML documents, module for: 11.1. Query Strings and Extra Path Information
mod_unique_id module, building with: 11.1. Query Strings and Extra Path Information
passing with HTTP requests: 11. Maintaining State

Unisys patent on LZW compression algorithm: 13.1.1.1. The LZW patent

Unix operating system

binmode function, not supporting: 13.2.1.1. binmode

ColdFusion language, versions for: 1.3.2. Alternatives to CGI

commands to locate perl: 15.1.2. The Pound-Bang

executable files, commands for: 1.2.2. Invoking CGI Scripts

executables, differentiating in filesystem: 1.2.2. Invoking CGI Scripts

file permissions: 10.1.2. Write Permissions

forward slashes (/) separating directories: 12.3.1. Search Application

Perl

linefeed and carriage return, representing on: 3.3.1.1. Outputting documents
speediness on: 1.3.1. Why Perl?

sendmail on: 9.4. sendmail

uptime command: 13.3.2. Using GD

variables (see environment variables)

unsolicited bulk email (see spam)

untainting data: 8.4.3. How Taintedness Is Removed

fgrep command search: 12.1. Searching One by One

untying hash tables from database files: 10.2.1. DB_File

update query screen: 10.4.2.2. Address book CGI script

updating databases: 10.3.4. Updating Data

updating HTML documents with links: 5.3.1.4. Specifying an alternative target

upload method (CGI.pm): 5.2.4. File Uploads with CGI.pm

UPLOAD_DIR: 5.2.4. File Uploads with CGI.pm

uploading files

handling with CGI.pm: 5.2.4. File Uploads with CGI.pm

uppercase, use in request methods: 2.3.1. The Request Line

uptime Unix system command: 13.3.2. Using GD

13.3.2. Using GD

URI module: 14.1.2. IO::Socket

URIs (Uniform Resource Identifiers): 2.1. URLs

URI::URL module: 2.1.3. URL Encoding

url method (CGI.pm): 5.2.1.6. url

url_escape and url_unescape functions: 2.1.3. URL Encoding

URLs (Uniform Resource Locators): 1.1. History

2.1. URLs

absolute and relative: 2.1.2. Absolute and Relative URLs

base for relative URLs in HTML documents: 2.4.2.1. Content-Base

bookmarklets, JavaScript: 7.4. Bookmarklets

breaking into components with URI module: 14.1.2. IO::Socket

CGI scripts: 1.2.2. Invoking CGI Scripts

calling from, self_url method and: 5.2.1.5. self_url
pointing to with tag: 5.3.2.1. start_html
specifying for receiving HTTP requests: 4.2.2. The <FORM> Tag

components of: 2.1.1. Elements of a URL

fragment identifiers: 2.1.1. Elements of a URL
hosts: 2.1.1. Elements of a URL
path information: 2.1.1. Elements of a URL
port numbers: 2.1.1. Elements of a URL
scheme (protocol): 2.1.1. Elements of a URL

to embpcgi.pl script: 6.4.1.3. embpcgi.pl

encoded characters: 4.3. Decoding Form Input

encoding characters in: 2.1.3. URL Encoding

URI::URL module: 2.1.3. URL Encoding

forwarding users to with Location header: 3.3.1.2. Forwarding to another URL

getting data from with LWP module: 14.5. CGI Gateway to XML Middleware

image displayed for image button, specifying: 4.2.3.8. Image buttons

invalid, 404 status code responses and: 3.3.1.3. Specifying status codes

IP addresses, problems with using in: 2.1.1. Elements of a URL

last page visited by user (Referer field): 2.3.2.7. Referer

manually constructed, passing parameters without equal (=) sign: 4.3. Decoding Form Input

parameters, visibility in GET requests: 8.2.5. Trusting the Browser

paths: 12.3.1. Search Application

extra information, maintaining state with: 11.1. Query Strings and Extra Path Information
mapping to CGI script directory on disk: 1.4.1.1. Configuring by directory
passing unique identifiers as extra information: 11. Maintaining State

query strings in: 2.1.1. Elements of a URL

4.1. Sending Data to the Server
4.3. Decoding Form Input
5.2.2.2. POST and the query string

redirection with redirect method: 5.3.1.5. Redirection

related to current, looking up with Netscape browser: 14.4. Writing an XML Parser

relative, advantages of: 16.1.3. Use Relative URLs

of requested resources, changed: 3.3.1.3. Specifying status codes

3.3.1.3. Specifying status codes

specifying for tag: 5.3.2.1. start_html

text, encoding: 4.1. Sending Data to the Server

unique identifier embedded in: 11.1. Query Strings and Extra Path Information

#USERID# as identifier for documents: 11.1. Query Strings and Extra Path Information

URNs (Uniform Resource Names): 2.1. URLs

use statement: 10.4.1.1. Connecting to DBI

use strict command: 1.2.1. Sample CGI

use vars statement: 10.4.2.2. Address book CGI script

user agent, creating with LWP: 14.1.3. LWP

User-Agent field: 2.3.2.5. User-Agent

user file, user names and encrypted passwords in: 2.3.2.4. Authorization

user registration form (example): 7.2.1.3. Validation example

user session: 11. Maintaining State

usernames: 2.4.2.10. WWW-Authenticate

users

authentication and identification (script): 3.4.2. User Authentication and Identification

email permissions, security risks of: 9.1.2. False Identities

error information, limiting view of: 5.5.2. CGI::Carp

input

tainted data, checking for: 8.4.1. How Taint Works

input from

handling securely: 8.2. Handling User Input
untainting: 8.4.3. How Taintedness Is Removed

tracking: 11. Maintaining State

web servers running as: 9.4.1. Command-Line Options

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