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<html><head><title>Index: U</title></head><body bgcolor="#FFFFFF" text="#000000"><!-- START OF BODY --><!-- TOP BANNER --><p><img src="../gifs/smbanns.gif" usemap="#banner-map" border=0 alt="Book Home" ></p><map name="banner-map"><AREA SHAPE="RECT" COORDS="0,0,466,71" HREF="../index.htm" ALT="Programming Perl"><AREA SHAPE="RECT" COORDS="467,0,514,18" HREF="../jobjects/fsearch.htm" ALT="Search this book"></map><!-- TOP INDEX LINKS --><p><a href="idx_0.htm">Symbols</a>| <a href="idx_a.htm">A</a>| <a href="idx_b.htm">B</a>| <a href="idx_c.htm">C</a>| <a href="idx_d.htm">D</a>| <a href="idx_e.htm">E</a>| <a href="idx_f.htm">F</a>| <a href="idx_g.htm">G</a>| <a href="idx_h.htm">H</a>| <a href="idx_i.htm">I</a>| <a href="idx_j.htm">J</a>| <a href="idx_k.htm">K</a>| <a href="idx_l.htm">L</a>| <a href="idx_m.htm">M</a>| <a href="idx_n.htm">N</a>| <a href="idx_o.htm">O</a>| <a href="idx_p.htm">P</a>| <a href="idx_q.htm">Q</a>| <a href="idx_r.htm">R</a>| <a href="idx_s.htm">S</a>| <a href="idx_t.htm">T</a>| <a href="idx_u.htm">U</a>| <a href="idx_v.htm">V</a>| <a href="idx_w.htm">W</a>| <a href="idx_x.htm">X</a>| <a href="idx_y.htm">Y</a>| <a href="idx_z.htm">Z</a></FONT><!-- INDEX SECTION BODY --><H1>Index: U</H1><DL><a name="-u-dump-core-command-line-switch"><dt>-u (dump core) command-line switch: <a href="../ch19_01.htm#INDEX-3446">19.1.3. Switches</a></dt><a name="-u-escape"><dt>\u escape: <a href="../ch05_02.htm#INDEX-1401">5.2.3. The s/// Operator (Substitution)</a></dt><a name="-u-setuid-file-test"><dt>-u (setuid) file test: <a href="../ch03_10.htm#INDEX-910">3.10. Named Unary and File Test Operators</a></dt><a name="-U-unsafe-command-line-switch"><dt>-U (unsafe) command-line switch: <a href="../ch19_01.htm#INDEX-3451">19.1.3. Switches</a></dt><a name="uc-function"><dt>uc function: <a href="../ch29_02.htm#INDEX-5353">29.2.184. uc</a></dt><a name="uc-operator"><dt>uc operator: <a href="../ch15_02.htm#INDEX-2851">15.2. Effects of Character Semantics</a></dt><a name="ucfirst-function"><dt>ucfirst function: <a href="../ch29_02.htm#INDEX-5356">29.2.185. ucfirst</a></dt><dd><dl><a name="ucfirst-operator"><dt><a href="../ch15_02.htm#INDEX-2852">15.2. Effects of Character Semantics</a></dt></dl></dd><a name="UDP"><dd><dl> <a name="passing-messages-with"> <dt>passing messages with: <a href="../ch16_05.htm#INDEX-3113">16.5.3. Message Passing</a></dt><a name="UDP-packets"><dt>packets: <a href="../ch16_05.htm#INDEX-3068">16.5. Sockets</a></dt></dl></dd><a name="$uid-file-statistic"><dt>$uid file statistic: <a href="../ch29_02.htm#INDEX-5292">29.2.165. stat</a></dt><a name="UID-user-ID"><dt>UID (user ID): <a href="../ch28_02.htm#INDEX-4442">28.2. Special Variables in Alphabetical Order</a></dt><dd><dl> <dt><a href="../ch29_02.htm#INDEX-4677">29.2.13. chown</a></dt> <a name="assumed"> <dt>assumed: <a href="../ch16_03.htm#INDEX-3016">16.3.2. Talking to Yourself</a></dt> <a name="passwd-file-entry-from"> <dt>passwd file entry from: <a href="../ch29_02.htm#INDEX-4892">29.2.63. getpwuid</a></dt></dl></dd><a name="umask-function"><dt>umask function: <a href="../ch29_02.htm#INDEX-5358">29.2.186. umask</a></dt><dd><dl></dl></dd><a name="unary-operators"><dt>unary operators: <a href="../ch01_05.htm#INDEX-192">1.5. Operators</a></dt><dd><dl> <dt><a href="../ch03_01.htm#INDEX-772">3. Unary and Binary Operators</a></dt> <dt><a href="../ch03_01.htm#INDEX-778">3. Unary and Binary Operators</a></dt> <a name="arithmetic"> <dt>arithmetic: <a href="../ch01_05.htm#INDEX-228">1.5.4. Unary Arithmetic Operators</a></dt> <a name="Boolean"> <dt>Boolean: <a href="../ch01_05.htm#INDEX-284">1.5.7. Some File Test Operators</a></dt> <a name="class-handler-invoking"> <dt>class handler, invoking: <a href="../ch13_01.htm#INDEX-2608">13.1. The overload Pragma</a></dt> <a name="functions-behaving-as"> <dt>functions, behaving as: <a href="../ch03_01.htm#INDEX-800">3.1. Terms and List Operators (Leftward)</a></dt> <a name="ideographic"> <dt>ideographic: <a href="../ch03_05.htm#INDEX-825">3.5. Ideographic Unary Operators</a></dt> <a name="list-operators-distinguishing-from"> <dt>list operators, distinguishing from: <a href="../ch03_10.htm#INDEX-878">3.10. Named Unary and File Test Operators</a></dt> <a name="named"> <dt>named: <a href="../ch02_11.htm#INDEX-765">2.11.3. Filename Globbing Operator</a></dt><dd><dl> <dt><a href="../ch03_01.htm#INDEX-806">3.1. Terms and List Operators (Leftward)</a></dt> <dt><a href="../ch03_10.htm#INDEX-871">3.10. Named Unary and File Test Operators</a></dt> <a name="listing-of"> <dt>listing of: <a href="../ch03_10.htm#INDEX-875">3.10. Named Unary and File Test Operators</a></dt> </dl></dd> <a name="prototyping-functions-as"> <dt>prototyping functions as: <a href="../ch06_04.htm#INDEX-1869">6.4.2. Care with Prototypes</a></dt></dl></dd><a name="undef-function"><dt>undef function: <a href="../ch24_02.htm#INDEX-4227">24.2.1. Time Efficiency</a></dt><dd><dl> <a name="undef-value"><dt><a href="../ch02_08.htm#INDEX-692">2.8.1. List Assignment</a></dt><dt><a href="../ch29_02.htm#INDEX-5362">29.2.187. undef</a></dt><a name="arrays-freeing-memory-from"> <dt>arrays, freeing memory from: <a href="../ch02_08.htm#INDEX-704">2.8.2. Array Length</a></dt></dl></dd><a name="undefined-scalars"><dt>undefined scalars: <a href="../ch02_06.htm#INDEX-527">2.6. Scalar Values</a></dt><a name="undefined-subroutines-calling-with-AUTOLOAD"><dt>undefined subroutines, calling with AUTOLOAD: <a href="../ch10_02.htm#INDEX-2252">10.2. Autoloading</a></dt><a name="Underscore-module"><dt>Underscore module: <a href="../ch14_01.htm#INDEX-2698">14.1.3. Magically Banishing $_</a></dt><a name="unequal"><dt>unequal (see <a href="idx_e.htm#equality-operators">equality operators</a>)</dt><a name="Unicode"><dt>Unicode: <a href="../ch02_01.htm#INDEX-405">2.1. Atoms</a></dt><dd><dl> <dt><a href="../ch15_01.htm#INDEX-2799">15. Unicode</a></dt> <a name="case-translation-tables"> <dt>case translation tables: <a href="../ch15_02.htm#INDEX-2853">15.2. Effects of Character Semantics</a></dt> <a name="converting-to-characters"> <dt>converting to characters: <a href="../ch29_02.htm#INDEX-4687">29.2.14. chr</a></dt> <a name="editors-for"> <dt>editors for: <a href="../ch15_02.htm#INDEX-2829">15.2. Effects of Character Semantics</a></dt> <a name="information-about"> <dt>information about: <a href="../ch05_04.htm#INDEX-1552">5.4.3. Unicode Properties</a></dt> <a name="line-separator-character"> <dt>line separator character: <a href="../ch02_02.htm#INDEX-417">2.2. Molecules</a></dt> <a name="locales-and"> <dt>locales and: <a href="../ch29_02.htm#INDEX-4966">29.2.82. lc</a></dt> <a name="paragraph-separator-character"> <dt>paragraph separator character: <a href="../ch02_02.htm#INDEX-416">2.2. Molecules</a></dt> <a name="Perl-properties-for"> <dt>Perl properties for: <a href="../ch05_04.htm#INDEX-1528">5.4. Character Classes</a></dt> <a name="properties"> <dt>properties: <a href="../ch05_04.htm#INDEX-1551">5.4.3. Unicode Properties</a></dt><dd><dl> <a name="bidirectional-rendering"> <dt>bidirectional rendering: <a href="../ch05_04.htm#INDEX-1563">5.4.3.2. Standard Unicode properties</a></dt> <a name="block-properties"> <dt>block properties: <a href="../ch05_04.htm#INDEX-1567">5.4.3.3. Unicode block properties</a></dt> <a name="decomposition-of-characters"> <dt>decomposition of characters: <a href="../ch05_04.htm#INDEX-1562">5.4.3.2. Standard Unicode properties</a></dt> <a name="Perl-character-class-shortcuts-and"> <dt>Perl character class shortcuts and: <a href="../ch05_04.htm#INDEX-1549">5.4.2. Classic Perl Character Class Shortcuts</a></dt> <a name="Perl-composites"> <dt>Perl composites: <a href="../ch05_04.htm#INDEX-1553">5.4.3.1. Perl's Unicode properties</a></dt> <a name="standard"> <dt>standard: <a href="../ch05_04.htm#INDEX-1555">5.4.3.2. Standard Unicode properties</a></dt> <a name="syllabaries-classifying-by-vowel-sounds"> <dt>syllabaries, classifying by vowel sounds: <a href="../ch05_04.htm#INDEX-1566">5.4.3.2. Standard Unicode properties</a></dt> </dl></dd> <a name="properties-database"> <dt>properties database: <a href="../ch15_02.htm#INDEX-2864">15.2. Effects of Character Semantics</a></dt> <a name="smiley-face"> <dt>smiley face: <a href="../ch29_02.htm#INDEX-4688">29.2.14. chr</a></dt> <a name="summary-of-accessing"> <dt>summary of, accessing: <a href="../ch15_02.htm#INDEX-2866">15.2. Effects of Character Semantics</a></dt> <a name="support-for-turning-on"> <dt>support for, turning on: <a href="../ch32_01.htm#INDEX-5528">32.1.6. Internationalization and Locale</a></dt> <a name="titlecase-converting-strings-to"> <dt>titlecase, converting strings to: <a href="../ch05_02.htm#INDEX-1452">5.2.4. The tr/// Operator (Transliteration)</a></dt> <a name="Unicode-Standard-Version-3.0"> <dt>Unicode Standard, Version 3.0: <a href="../ch15_02.htm#INDEX-2867">15.2. Effects of Character Semantics</a></dt> <a name="use-in-Perl-caveats-on"> <dt>use in Perl, caveats on: <a href="../ch15_03.htm#INDEX-2869">15.3. Caution, [ren2bold] Working</a></dt> <a name="wildcard-metasymbols-matching-with"> <dt>wildcard metasymbols, matching with: <a href="../ch05_03.htm#INDEX-1519">5.3.3. Wildcard Metasymbols</a></dt></dl></dd><a name="Unicode-characters"><dt>Unicode characters: <a href="../ch01_07.htm#INDEX-361">1.7. Regular Expressions</a></dt><dd><dl> <a name="in-identifiers"> <dt>in identifiers: <a href="../ch02_05.htm#INDEX-486">2.5. Names</a></dt> <a name="smiley"> <dt>smiley: <a href="../ch02_06.htm#INDEX-568">2.6.2. String Literals</a></dt></dl></dd><a name="uninitialized-variables"><dt>uninitialized, variables: <a href="../ch01_02.htm#INDEX-63">1.2.1.1. Singularities</a></dt><a name="UNIVERSAL-class"><dt>UNIVERSAL class: <a href="../ch12_05.htm#INDEX-2471">12.5.3. UNIVERSAL: The Ultimate Ancestor Class</a></dt><dd><dl> <a name="methods-adding-to"> <dt>methods, adding to: <a href="../ch12_05.htm#INDEX-2480">12.5.3. UNIVERSAL: The Ultimate Ancestor Class</a></dt></dl></dd><a name="UNIVERSAL-module"><dt>UNIVERSAL module: <a href="../ch32_01.htm#INDEX-5666">32.1.14. Convenient Classes</a></dt><a name="Unix"><dd><dl> <a name="Unix-systems"><dt><a href="../ch01_02.htm#INDEX-50">1.2.1.1. Singularities</a></dt><a name="CPAN-modules-installing-on"> <dt>CPAN modules, installing on: <a href="../ch22_02.htm#INDEX-3924">22.2.1. Decompressing and Unpacking CPAN Modules</a></dt> <a name="fileglobbing"> <dt>fileglobbing: <a href="../ch32_01.htm#INDEX-5477">32.1.4. Filenames, Filesystems, and File Locking</a></dt> <a name="File::Spec::Unix-module"> <dt>File::Spec::Unix module: <a href="../ch32_01.htm#INDEX-5489">32.1.4. Filenames, Filesystems, and File Locking</a></dt> <a name="security-bugs"> <dt>security bugs: <a href="../ch23_02.htm#INDEX-4021">23.2.1. Unix Kernel Security Bugs</a></dt> <a name="test-command-test-scripts-and"> <a name="sockets-for"> <dt>sockets for: <a href="../ch32_01.htm#INDEX-5554">32.1.8. Networking and Interprocess Communication</a></dt><dt>test command, test scripts and: <a href="../ch01_03.htm#INDEX-164">1.3.1. How to Do It</a></dt><a name="truncating-kernel-interpretation-of-#!-line"> <dt>truncating kernel interpretation of #! line: <a href="../ch19_01.htm#INDEX-3335">19.1. Command Processing</a></dt> </dl></dd> <a name="unless-modifier"><dt>unless modifier: <a href="../ch04_01.htm#INDEX-1043">4.1. Simple Statements</a></dt><a name="unless-statements"><dt>unless statements: <a href="../ch01_06.htm#INDEX-302">1.6.1.1. The if and unless statements</a></dt><dd><dl> <a name="if-statements-using-instead-of"> <dt>if statements, using instead of: <a href="../ch04_03.htm#INDEX-1069">4.3. if and unless Statements</a></dt></dl></dd><a name="unlink-function"><dt>unlink function: <a href="../ch29_02.htm#INDEX-5364">29.2.188. unlink</a></dt><dd><dl><a name="unlink-operator"><dt><a href="../ch02_07.htm#INDEX-654">2.7.2. Boolean Context</a></dt>⌨️ 快捷键说明
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