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Index: U

-u (dump core) command-line switch: 19.1.3. Switches

\u escape: 5.2.3. The s/// Operator (Substitution)

-u (setuid) file test: 3.10. Named Unary and File Test Operators

-U (unsafe) command-line switch: 19.1.3. Switches

uc function: 29.2.184. uc

uc operator: 15.2. Effects of Character Semantics

ucfirst function: 29.2.185. ucfirst

15.2. Effects of Character Semantics

passing messages with: 16.5.3. Message Passing
packets: 16.5. Sockets

$uid file statistic: 29.2.165. stat

UID (user ID): 28.2. Special Variables in Alphabetical Order

29.2.13. chown
assumed: 16.3.2. Talking to Yourself
passwd file entry from: 29.2.63. getpwuid

umask function: 29.2.186. umask

unary operators: 1.5. Operators

3. Unary and Binary Operators

arithmetic: 1.5.4. Unary Arithmetic Operators

Boolean: 1.5.7. Some File Test Operators

class handler, invoking: 13.1. The overload Pragma

functions, behaving as: 3.1. Terms and List Operators (Leftward)

ideographic: 3.5. Ideographic Unary Operators

list operators, distinguishing from: 3.10. Named Unary and File Test Operators

named: 2.11.3. Filename Globbing Operator

3.1. Terms and List Operators (Leftward)
3.10. Named Unary and File Test Operators
listing of: 3.10. Named Unary and File Test Operators

prototyping functions as: 6.4.2. Care with Prototypes

undef function: 24.2.1. Time Efficiency

2.8.1. List Assignment
29.2.187. undef
arrays, freeing memory from: 2.8.2. Array Length

undefined scalars: 2.6. Scalar Values

undefined subroutines, calling with AUTOLOAD: 10.2. Autoloading

Underscore module: 14.1.3. Magically Banishing $_

unequal (see equality operators)

Unicode: 2.1. Atoms

15. Unicode

case translation tables: 15.2. Effects of Character Semantics

converting to characters: 29.2.14. chr

editors for: 15.2. Effects of Character Semantics

information about: 5.4.3. Unicode Properties

line separator character: 2.2. Molecules

locales and: 29.2.82. lc

paragraph separator character: 2.2. Molecules

Perl properties for: 5.4. Character Classes

properties: 5.4.3. Unicode Properties

bidirectional rendering: 5.4.3.2. Standard Unicode properties
block properties: 5.4.3.3. Unicode block properties
decomposition of characters: 5.4.3.2. Standard Unicode properties
Perl character class shortcuts and: 5.4.2. Classic Perl Character Class Shortcuts
Perl composites: 5.4.3.1. Perl's Unicode properties
standard: 5.4.3.2. Standard Unicode properties
syllabaries, classifying by vowel sounds: 5.4.3.2. Standard Unicode properties

properties database: 15.2. Effects of Character Semantics

smiley face: 29.2.14. chr

summary of, accessing: 15.2. Effects of Character Semantics

support for, turning on: 32.1.6. Internationalization and Locale

titlecase, converting strings to: 5.2.4. The tr/// Operator (Transliteration)

Unicode Standard, Version 3.0: 15.2. Effects of Character Semantics

use in Perl, caveats on: 15.3. Caution, [ren2bold] Working

wildcard metasymbols, matching with: 5.3.3. Wildcard Metasymbols

Unicode characters: 1.7. Regular Expressions

in identifiers: 2.5. Names
smiley: 2.6.2. String Literals

uninitialized, variables: 1.2.1.1. Singularities

UNIVERSAL class: 12.5.3. UNIVERSAL: The Ultimate Ancestor Class

methods, adding to: 12.5.3. UNIVERSAL: The Ultimate Ancestor Class

UNIVERSAL module: 32.1.14. Convenient Classes

1.2.1.1. Singularities
CPAN modules, installing on: 22.2.1. Decompressing and Unpacking CPAN Modules
fileglobbing: 32.1.4. Filenames, Filesystems, and File Locking
File::Spec::Unix module: 32.1.4. Filenames, Filesystems, and File Locking
security bugs: 23.2.1. Unix Kernel Security Bugs
sockets for: 32.1.8. Networking and Interprocess Communication
test command, test scripts and: 1.3.1. How to Do It
truncating kernel interpretation of #! line: 19.1. Command Processing

unless modifier: 4.1. Simple Statements

unless statements: 1.6.1.1. The if and unless statements

if statements, using instead of: 4.3. if and unless Statements

unlink function: 29.2.188. unlink

2.7.2. Boolean Context

unordered lists (see hashes)

unpack: 25.2. Endianness and Number Width

unpack function: 29.2.189. unpack

template characters for: 29.2.108. pack

unpacking CPAN modules: 22.2.1. Decompressing and Unpacking CPAN Modules

unqualified, names, searching for: 2.5.1. Name Lookups

unsafe operations: 19.1.3. Switches

unshift function: 9. Data Structures

29.2.190. unshift

unsigned integers, lists of, storing: 29.2.195. vec

unsigned shorts: 29.2.162. sprintf

untie function: 14. Tied Variables

14.5. A Subtle Untying Trap
29.2.21. dbmclose
29.2.191. untie
outstanding references, not eliminating: 14.1. Tying Scalars

until loops: 4.4.1. while and until Statements

until modifier: 4.1. Simple Statements

untying trap: 14.5. A Subtle Untying Trap

up method: 17.2.3.2. Semaphores

upcase function: 6.2.1. Tricks with Parameter Lists

uppercase, converting to: 2.6.2. String Literals

5.2.3. The s/// Operator (Substitution)

use: 4.7. Global Declarations

global and lexical scoping of: 4.8. Scoped Declarations

use attributes pragma: 6.5. Subroutine Attributes

use base declarations: 12.5.1. Inheritance Through @ISA

pseudohash implementations, requirement with: 12.7.1. Field Declarations with use fields

use base pragma: 31.3. use base

use blib pragma: 31.4. use blib

use bytes pragma: 15.2. Effects of Character Semantics

use charnames pragma: 15.2. Effects of Character Semantics

use command: 10. Packages

use declarations: 1.2.1.4. Simplicities

4.7. Global Declarations
4.9. Pragmas
(see also pragmas)
modules: 11.1. Using Modules
tie function and: 14. Tied Variables
use strict: 24.1.2. Frequently Ignored Advice

use fields declarations: 12.5.1. Inheritance Through @ISA

use fields pragma: 12.7.1. Field Declarations with use fields

use filetest pragma: 3.10. Named Unary and File Test Operators

use overload pragma: 13.1. The overload Pragma

use statement: 21.1. How Perl Works

use subs declarations: 12.5.4. Method Autoloading

use utf8 pragma: 5.3.3. Wildcard Metasymbols

use warnings pragma: 20. The Perl Debugger

Usenet, Perl modules for: 22.1. The CPAN modules Directory

user-defined functions (see subroutines)

user-defined subroutines: 1.2.2. Verbs

1.2.2. Verbs
(see also subroutines)

user efficiency, Perl programming: 24.2.6. User Efficiency

user ID (see UID)

user interfaces, modules providing: 32.1.11. User Interfaces

User::grent module: 29.2.44. getgrent

32.1.7. Operating System Interfaces

username, passwd file entry from: 29.2.62. getpwnam

User::pwent module: 29.2.63. getpwuid

32.1.7. Operating System Interfaces
Class::Struct, using to create objects and accessors: 32.6. Class::Struct

users

authenticating, Perl modules for: 22.1. The CPAN modules Directory
CPU times: 29.2.181. times
granting limited privileges to: 23.1. Handling Insecure Data
information about, functions for getting: 29.1. Perl Functions by Category

UTF-8: 2.1. Atoms

characters, converting to integers: 15.2. Effects of Character Semantics
globally switching interfaces to: 28.2. Special Variables in Alphabetical Order
module: 32.1.6. Internationalization and Locale
Perl version: 15.1. Building Character
pragma: 15.2. Effects of Character Semantics
strings, converting to/from byte strings: 15.1. Building Character
variable-length character encoding: 15.1. Building Character

utime function: 29.2.193. utime

utmp file (see /etc/utmp file)

UV (internal unsigned integer value): 21.2. Internal Data Types

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