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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML
><HEAD
><TITLE
>Advanced Bash-Scripting Guide</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REL="NEXT"
TITLE="Introduction"
HREF="part1.html"></HEAD
><BODY
CLASS="BOOK"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="BOOK"
><A
NAME="AEN1"
></A
><DIV
CLASS="TITLEPAGE"
><H1
CLASS="TITLE"
><A
NAME="AEN2"
></A
>Advanced Bash-Scripting Guide</H1
><H2
CLASS="SUBTITLE"
>An in-depth exploration of the art of shell scripting</H2
><H3
CLASS="AUTHOR"
><A
NAME="AEN5"
></A
>Mendel Cooper</H3
><DIV
CLASS="AFFILIATION"
><SPAN
CLASS="ORGNAME"
><BR></SPAN
><DIV
CLASS="ADDRESS"
><P
CLASS="ADDRESS"
><TT
CLASS="EMAIL"
>&#60;<A
HREF="mailto:thegrendel.abs@gmail.com"
>thegrendel.abs@gmail.com</A
>&#62;</TT
></P
></DIV
></DIV
><SPAN
CLASS="RELEASEINFO"
>10<BR></SPAN
><P
CLASS="PUBDATE"
>10 Mar 2014<BR></P
><DIV
CLASS="REVHISTORY"
><TABLE
WIDTH="100%"
BORDER="0"
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
COLSPAN="3"
><B
>Revision History</B
></TH
></TR
><TR
><TD
ALIGN="LEFT"
>Revision 6.5</TD
><TD
ALIGN="LEFT"
>05 Apr 2012</TD
><TD
ALIGN="LEFT"
>Revised by: mc</TD
></TR
><TR
><TD
ALIGN="LEFT"
COLSPAN="3"
>'TUNGSTENBERRY' release</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Revision 6.6</TD
><TD
ALIGN="LEFT"
>27 Nov 2012</TD
><TD
ALIGN="LEFT"
>Revised by: mc</TD
></TR
><TR
><TD
ALIGN="LEFT"
COLSPAN="3"
>'YTTERBIUMBERRY' release</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Revision 10</TD
><TD
ALIGN="LEFT"
>10 Mar 2014</TD
><TD
ALIGN="LEFT"
>Revised by: mc</TD
></TR
><TR
><TD
ALIGN="LEFT"
COLSPAN="3"
>'PUBLICDOMAIN' release</TD
></TR
></TABLE
></DIV
><DIV
><DIV
CLASS="ABSTRACT"
><A
NAME="AEN31"
></A
><P
></P
><P
>This tutorial assumes no previous knowledge of
scripting or programming, yet progresses rapidly toward an
intermediate/advanced level of instruction <EM
>. . . all
the while sneaking in little nuggets of <SPAN
CLASS="TRADEMARK"
>UNIX</SPAN
>&reg; wisdom and lore</EM
>. It
serves as a textbook, a manual for self-study, and as a reference and
source of knowledge on shell scripting techniques. The exercises
and heavily-commented examples invite active reader participation,
under the premise that <TT
CLASS="USERINPUT"
><B
>the only way to really learn
scripting is to write scripts</B
></TT
>.</P
><P
>This book is suitable for classroom use as a
general introduction to programming concepts.</P
><P
>This document is herewith granted to the Public Domain.
<TT
CLASS="USERINPUT"
><B
>No copyright!</B
></TT
></P
><P
></P
></DIV
></DIV
><HR></DIV
><H1
><A
NAME="AEN39"
></A
>Dedication</H1
><P
>For Anita, the source of all the magic</P
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>Part 1. <A
HREF="part1.html"
>Introduction</A
></DT
><DD
><DL
><DT
>1. <A
HREF="why-shell.html"
>Shell Programming!</A
></DT
><DT
>2. <A
HREF="sha-bang.html"
>Starting Off With a Sha-Bang</A
></DT
></DL
></DD
><DT
>Part 2. <A
HREF="part2.html"
>Basics</A
></DT
><DD
><DL
><DT
>3. <A
HREF="special-chars.html"
>Special Characters</A
></DT
><DT
>4. <A
HREF="variables.html"
>Introduction to Variables and Parameters</A
></DT
><DT
>5. <A
HREF="quoting.html"
>Quoting</A
></DT
><DT
>6. <A
HREF="exit-status.html"
>Exit and Exit Status</A
></DT
><DT
>7. <A
HREF="tests.html"
>Tests</A
></DT
><DT
>8. <A
HREF="operations.html"
>Operations and Related Topics</A
></DT
></DL
></DD
><DT
>Part 3. <A
HREF="part3.html"
>Beyond the Basics</A
></DT
><DD
><DL
><DT
>9. <A
HREF="variables2.html"
>Another Look at Variables</A
></DT
><DT
>10. <A
HREF="manipulatingvars.html"
>Manipulating Variables</A
></DT
><DT
>11. <A
HREF="loops.html"
>Loops and Branches</A
></DT
><DT
>12. <A
HREF="commandsub.html"
>Command Substitution</A
></DT
><DT
>13. <A
HREF="arithexp.html"
>Arithmetic Expansion</A
></DT
><DT
>14. <A
HREF="recess-time.html"
>Recess Time</A
></DT
></DL
></DD
><DT
>Part 4. <A
HREF="part4.html"
>Commands</A
></DT
><DD
><DL
><DT
>15. <A
HREF="internal.html"
>Internal Commands and Builtins</A
></DT
><DT
>16. <A
HREF="external.html"
>External Filters, Programs and Commands</A
></DT
><DT
>17. <A
HREF="system.html"
>System and Administrative Commands</A
></DT
></DL
></DD
><DT
>Part 5. <A
HREF="part5.html"
>Advanced Topics</A
></DT
><DD
><DL
><DT
>18. <A
HREF="regexp.html"
>Regular Expressions</A
></DT
><DT
>19. <A
HREF="here-docs.html"
>Here Documents</A
></DT
><DT
>20. <A
HREF="io-redirection.html"
>I/O Redirection</A
></DT
><DT
>21. <A
HREF="subshells.html"
>Subshells</A
></DT
><DT
>22. <A
HREF="restricted-sh.html"
>Restricted Shells</A
></DT
><DT
>23. <A
HREF="process-sub.html"
>Process Substitution</A
></DT
><DT
>24. <A
HREF="functions.html"
>Functions</A
></DT
><DT
>25. <A
HREF="aliases.html"
>Aliases</A
></DT
><DT
>26. <A
HREF="list-cons.html"
>List Constructs</A
></DT
><DT
>27. <A
HREF="arrays.html"
>Arrays</A
></DT
><DT
>28. <A
HREF="ivr.html"
>Indirect References</A
></DT
><DT
>29. <A
HREF="devproc.html"
><TT
CLASS="FILENAME"
>/dev</TT
> and <TT
CLASS="FILENAME"
>/proc</TT
></A
></DT
><DT
>30. <A
HREF="networkprogramming.html"
>Network Programming</A
></DT
><DT
>31. <A
HREF="zeros.html"
>Of Zeros and Nulls</A
></DT
><DT
>32. <A
HREF="debugging.html"
>Debugging</A
></DT
><DT
>33. <A
HREF="options.html"
>Options</A
></DT
><DT
>34. <A
HREF="gotchas.html"
>Gotchas</A
></DT
><DT
>35. <A
HREF="scrstyle.html"
>Scripting With Style</A
></DT
><DT
>36. <A
HREF="miscellany.html"
>Miscellany</A
></DT
><DT
>37. <A
HREF="bash2.html"
>Bash, versions 2, 3, and 4</A
></DT
></DL
></DD
><DT
>38. <A
HREF="endnotes.html"
>Endnotes</A
></DT
><DD
><DL
><DT
>38.1. <A
HREF="authorsnote.html"
>Author's Note</A
></DT
><DT
>38.2. <A
HREF="aboutauthor.html"
>About the Author</A
></DT
><DT
>38.3. <A
HREF="wherehelp.html"
>Where to Go For Help</A
></DT
><DT
>38.4. <A
HREF="toolsused.html"
>Tools Used to Produce This Book</A
></DT
><DT
>38.5. <A
HREF="credits.html"
>Credits</A
></DT
><DT
>38.6. <A
HREF="disclaimer.html"
>Disclaimer</A
></DT
></DL
></DD
><DT
><A
HREF="biblio.html"
>Bibliography</A
></DT
><DT
>A. <A
HREF="contributed-scripts.html"
>Contributed Scripts</A
></DT
><DT
>B. <A
HREF="refcards.html"
>Reference Cards</A
></DT
><DT
>C. <A
HREF="sedawk.html"
>A Sed and Awk Micro-Primer</A
></DT
><DD
><DL
><DT
>C.1. <A
HREF="x23170.html"
>Sed</A
></DT
><DT
>C.2. <A
HREF="awk.html"
>Awk</A
></DT
></DL
></DD
><DT
>D. <A
HREF="pathmanagement.html"
>Parsing and Managing Pathnames</A
></DT
><DT
>E. <A
HREF="exitcodes.html"
>Exit Codes With Special Meanings</A
></DT
><DT
>F. <A
HREF="ioredirintro.html"
>A Detailed Introduction to I/O and I/O Redirection</A
></DT
><DT
>G. <A
HREF="command-line-options.html"
>Command-Line Options</A
></DT
><DD
><DL
><DT
>G.1. <A
HREF="standard-options.html"
>Standard Command-Line Options</A
></DT
><DT
>G.2. <A
HREF="bash-options.html"
>Bash Command-Line Options</A
></DT
></DL
></DD
><DT
>H. <A
HREF="files.html"
>Important Files</A
></DT
><DT
>I. <A
HREF="systemdirs.html"
>Important System Directories</A
></DT
><DT
>J. <A
HREF="tabexpansion.html"
>An Introduction to Programmable Completion</A
></DT
><DT
>K. <A
HREF="localization.html"
>Localization</A
></DT
><DT
>L. <A
HREF="histcommands.html"
>History Commands</A
></DT
><DT
>M. <A
HREF="sample-bashrc.html"
>Sample <TT
CLASS="FILENAME"
>.bashrc</TT
> and
<TT
CLASS="FILENAME"
>.bash_profile</TT
> Files</A
></DT
><DT
>N. <A
HREF="dosbatch.html"
>Converting DOS Batch Files to Shell Scripts</A
></DT
><DT
>O. <A
HREF="exercises.html"
>Exercises</A
></DT
><DD
><DL
><DT
>O.1. <A
HREF="scriptanalysis.html"
>Analyzing Scripts</A
></DT
><DT
>O.2. <A
HREF="writingscripts.html"
>Writing Scripts</A
></DT
></DL
></DD
><DT
>P. <A
HREF="revisionhistory.html"
>Revision History</A
></DT
><DT
>Q. <A
HREF="mirrorsites.html"
>Download and Mirror Sites</A
></DT
><DT
>R. <A
HREF="todolist.html"
>To Do List</A
></DT
><DT
>S. <A
HREF="copyright.html"
>Copyright</A
></DT
><DT
>T. <A
HREF="asciitable.html"
>ASCII Table</A
></DT
><DT
><A
HREF="xrefindex.html"
>Index</A
></DT
></DL
></DIV
><DIV
CLASS="LOT"
><DL
CLASS="LOT"
><DT
><B
>List of Tables</B
></DT
><DT
>8-1. <A
HREF="opprecedence.html#AEN4294"
>Operator Precedence</A
></DT
><DT
>15-1. <A
HREF="x9644.html#JOBIDTABLE"
>Job identifiers</A
></DT
><DT
>33-1. <A
HREF="options.html#AEN19601"
>Bash options</A
></DT
><DT
>36-1. <A
HREF="colorizing.html#AEN20327"
>Numbers representing colors in Escape Sequences</A
></DT
><DT
>B-1. <A
HREF="refcards.html#AEN22402"
>Special Shell Variables</A
></DT
><DT
>B-2. <A
HREF="refcards.html#AEN22473"
>TEST Operators: Binary Comparison</A
></DT
><DT
>B-3. <A
HREF="refcards.html#AEN22593"
>TEST Operators: Files</A
></DT
><DT
>B-4. <A
HREF="refcards.html#AEN22728"
>Parameter Substitution and Expansion</A
></DT
><DT
>B-5. <A
HREF="refcards.html#AEN22828"
>String Operations</A
></DT
><DT
>B-6. <A
HREF="refcards.html#AEN22979"
>Miscellaneous Constructs</A
></DT
><DT
>C-1. <A
HREF="x23170.html#AEN23200"
>Basic sed operators</A
></DT
><DT
>C-2. <A
HREF="x23170.html#AEN23271"
>Examples of sed operators</A
></DT
><DT
>E-1. <A
HREF="exitcodes.html#AEN23549"
><I
CLASS="FIRSTTERM"
>Reserved</I
> Exit Codes</A
></DT
><DT
>N-1. <A
HREF="dosbatch.html#AEN24336"
>Batch file keywords / variables / operators, and their shell equivalents</A
></DT
><DT
>N-2. <A
HREF="dosbatch.html#AEN24545"
>DOS commands and their UNIX equivalents</A
></DT
><DT
>P-1. <A
HREF="revisionhistory.html#AEN25364"
>Revision History</A
></DT
></DL
></DIV
><DIV
CLASS="LOT"
><DL
CLASS="LOT"
><DT
><B
>List of Examples</B
></DT
><DT
>2-1. <A
HREF="sha-bang.html#EX1"
><I
CLASS="FIRSTTERM"
>cleanup</I
>: A script to clean up log
files in /var/log</A
></DT
><DT
>2-2. <A
HREF="sha-bang.html#EX1A"
><I
CLASS="FIRSTTERM"
>cleanup</I
>: An improved clean-up
script</A
></DT
><DT
>2-3. <A
HREF="sha-bang.html#EX2"
><I
CLASS="FIRSTTERM"
>cleanup</I
>: An enhanced
and generalized version of above scripts.</A
></DT
><DT
>3-1. <A
HREF="special-chars.html#EX8"
>Code blocks and I/O redirection</A
></DT
><DT
>3-2. <A
HREF="special-chars.html#RPMCHECK"
>Saving the output of a code block to a file</A
></DT
><DT
>3-3. <A
HREF="special-chars.html#BGLOOP"
>Running a loop in the background</A
></DT
><DT
>3-4. <A
HREF="special-chars.html#EX58"
>Backup of all files changed in last day</A
></DT
><DT
>4-1. <A
HREF="varsubn.html#EX9"
>Variable assignment and substitution</A
></DT
><DT
>4-2. <A
HREF="varassignment.html#EX15"
>Plain Variable Assignment</A
></DT
><DT
>4-3. <A
HREF="varassignment.html#EX16"
>Variable Assignment, plain and fancy</A
></DT
><DT
>4-4. <A
HREF="untyped.html#INTORSTRING"
>Integer or string?</A
></DT
><DT
>4-5. <A
HREF="othertypesv.html#EX17"
>Positional Parameters</A
></DT
><DT
>4-6. <A
HREF="othertypesv.html#EX18"
><I
CLASS="FIRSTTERM"
>wh</I
>, <I
CLASS="FIRSTTERM"
> whois</I
> domain name lookup</A
></DT
><DT
>4-7. <A
HREF="othertypesv.html#EX19"
>Using <I
CLASS="FIRSTTERM"
>shift</I
></A
></DT
><DT
>5-1. <A
HREF="quotingvar.html#WEIRDVARS"
>Echoing Weird Variables</A
></DT
><DT
>5-2. <A
HREF="escapingsection.html#ESCAPED"
>Escaped Characters</A
></DT
><DT
>5-3. <A
HREF="escapingsection.html#BASHEK"
>Detecting key-presses</A
></DT
><DT
>6-1. <A
HREF="exit-status.html#EX5"
>exit / exit status</A
></DT
><DT
>6-2. <A
HREF="exit-status.html#NEGCOND"
>Negating a condition using <SPAN
CLASS="TOKEN"
>!</SPAN
></A
></DT
><DT
>7-1. <A
HREF="testconstructs.html#EX10"
>What is truth?</A
></DT
><DT
>7-2. <A
HREF="testconstructs.html#EX11"
>Equivalence of <I
CLASS="FIRSTTERM"
>test</I
>,
<TT
CLASS="FILENAME"
>/usr/bin/test</TT
>, <SPAN
CLASS="TOKEN"
>[ ]</SPAN
>,
and <TT
CLASS="FILENAME"
>/usr/bin/[</TT
></A
></DT
><DT
>7-3. <A
HREF="testconstructs.html#ARITHTESTS"
>Arithmetic Tests using <SPAN
CLASS="TOKEN"
>(( ))</SPAN
></A
></DT
><DT
>7-4. <A
HREF="fto.html#BROKENLINK"
>Testing for broken links</A
></DT
><DT
>7-5. <A
HREF="comparison-ops.html#EX13"
>Arithmetic and string comparisons</A
></DT
><DT
>7-6. <A
HREF="comparison-ops.html#STRTEST"
>Testing whether a string is <I
CLASS="FIRSTTERM"
>null</I
></A
></DT
><DT
>7-7. <A
HREF="comparison-ops.html#EX14"
><I
CLASS="FIRSTTERM"
>zmore</I
></A
></DT
><DT
>8-1. <A
HREF="ops.html#GCD"
>Greatest common divisor</A
></DT
><DT
>8-2. <A
HREF="ops.html#ARITHOPS"
>Using Arithmetic Operations</A
></DT
><DT
>8-3. <A
HREF="ops.html#ANDOR"
>Compound Condition Tests Using &#38;&#38; and ||</A
></DT
><DT
>8-4. <A
HREF="numerical-constants.html#NUMBERS"
>Representation of numerical constants</A
></DT
><DT
>8-5. <A
HREF="dblparens.html#CVARS"
>C-style manipulation of variables</A
></DT
><DT
>9-1. <A
HREF="internalvariables.html#IFSH"
>$IFS and whitespace</A
></DT
><DT
>9-2. <A
HREF="internalvariables.html#TMDIN"
>Timed Input</A
></DT
><DT
>9-3. <A
HREF="internalvariables.html#TIMEOUT"
>Once more, timed input</A
></DT
><DT
>9-4. <A
HREF="internalvariables.html#TOUT"
>Timed <I
CLASS="FIRSTTERM"
>read</I
></A
></DT
><DT
>9-5. <A
HREF="internalvariables.html#AMIROOT"
>Am I root?</A
></DT
><DT
>9-6. <A
HREF="internalvariables.html#ARGLIST"
><I
CLASS="FIRSTTERM"
>arglist</I
>: Listing arguments
with $* and $@</A
></DT
><DT
>9-7. <A
HREF="internalvariables.html#INCOMPAT"
>Inconsistent <TT
CLASS="VARNAME"
>$*</TT
> and <TT
CLASS="VARNAME"
>$@</TT
> behavior</A
></DT
><DT
>9-8. <A
HREF="internalvariables.html#IFSEMPTY"
><TT
CLASS="VARNAME"
>$*</TT
> and <TT
CLASS="VARNAME"
>$@</TT
> when
<TT
CLASS="VARNAME"
>$IFS</TT
> is empty</A
></DT
><DT
>9-9. <A
HREF="internalvariables.html#USCREF"
>Underscore variable</A
></DT
><DT
>9-10. <A
HREF="declareref.html#EX20"
>Using <I
CLASS="FIRSTTERM"
>declare</I
> to type variables</A
></DT
><DT
>9-11. <A
HREF="randomvar.html#EX21"
>Generating random numbers</A
></DT
><DT
>9-12. <A
HREF="randomvar.html#PICKCARD"
>Picking a random card from a deck</A
></DT
><DT
>9-13. <A
HREF="randomvar.html#BROWNIAN"
>Brownian Motion Simulation</A
></DT
><DT
>9-14. <A
HREF="randomvar.html#RANDOMBETWEEN"
>Random between values</A
></DT
><DT
>9-15. <A
HREF="randomvar.html#RANDOMTEST"
>Rolling a single die with RANDOM</A
></DT
><DT
>9-16. <A
HREF="randomvar.html#SEEDINGRANDOM"
>Reseeding RANDOM</A
></DT
><DT
>9-17. <A
HREF="randomvar.html#RANDOM2"
>Pseudorandom numbers, using <A
HREF="awk.html#AWKREF"
>awk</A
></A
></DT
><DT
>10-1. <A
HREF="string-manipulation.html#PARAGRAPHSPACE"
>Inserting a blank line between paragraphs in a text file</A
></DT
><DT
>10-2. <A
HREF="string-manipulation.html#RANDSTRING"
>Generating an 8-character <SPAN
CLASS="QUOTE"
>"random"</SPAN
>
string</A
></DT
><DT
>10-3. <A
HREF="string-manipulation.html#CVT"
>Converting graphic file formats, with filename change</A
></DT
><DT
>10-4. <A
HREF="string-manipulation.html#RA2OGG"
>Converting streaming audio files to
<I
CLASS="FIRSTTERM"
>ogg</I
></A
></DT
><DT
>10-5. <A
HREF="string-manipulation.html#GETOPTSIMPLE"
>Emulating <I
CLASS="FIRSTTERM"
>getopt</I
></A
></DT
><DT
>10-6. <A
HREF="string-manipulation.html#SUBSTRINGEX"
>Alternate ways of extracting and locating substrings</A
></DT
><DT
>10-7. <A
HREF="parameter-substitution.html#EX6"
>Using parameter substitution and error messages</A
></DT
><DT
>10-8. <A
HREF="parameter-substitution.html#USAGEMESSAGE"
>Parameter substitution and <SPAN
CLASS="QUOTE"
>"usage"</SPAN
> messages</A
></DT
><DT
>10-9. <A
HREF="parameter-substitution.html#LENGTH"
>Length of a variable</A
></DT
><DT
>10-10. <A
HREF="parameter-substitution.html#PATTMATCHING"
>Pattern matching in parameter substitution</A
></DT
><DT
>10-11. <A
HREF="parameter-substitution.html#RFE"
>Renaming file extensions<SPAN
CLASS="TOKEN"
>:</SPAN
></A
></DT
><DT
>10-12. <A
HREF="parameter-substitution.html#EX7"
>Using pattern matching to parse arbitrary strings</A
></DT
><DT
>10-13. <A
HREF="parameter-substitution.html#VARMATCH"
>Matching patterns at prefix or suffix of string</A
></DT
><DT
>11-1. <A
HREF="loops1.html#EX22"
>Simple <I
CLASS="FIRSTTERM"
>for</I
> loops</A
></DT
><DT
>11-2. <A
HREF="loops1.html#EX22A"
><I
CLASS="FIRSTTERM"
>for</I
> loop with two parameters in each
[list] element</A
></DT
><DT
>11-3. <A
HREF="loops1.html#FILEINFO"
><EM
>Fileinfo:</EM
> operating on a file list
contained in a variable</A
></DT
><DT
>11-4. <A
HREF="loops1.html#FILEINFO01"
>Operating on a parameterized file list</A
></DT
><DT
>11-5. <A
HREF="loops1.html#LISTGLOB"
>Operating on files with a <I
CLASS="FIRSTTERM"
>for</I
> loop</A
></DT
><DT
>11-6. <A
HREF="loops1.html#EX23"
>Missing <TT
CLASS="USERINPUT"
><B
>in [list]</B
></TT
> in a
<I
CLASS="FIRSTTERM"
>for</I
> loop</A
></DT
><DT
>11-7. <A
HREF="loops1.html#FORLOOPCMD"
>Generating the <TT
CLASS="USERINPUT"
><B
>[list]</B
></TT
> in
a <I
CLASS="FIRSTTERM"
>for</I
> loop with command substitution</A
></DT
><DT
>11-8. <A
HREF="loops1.html#BINGREP"
>A <I
CLASS="FIRSTTERM"
>grep</I
> replacement
for binary files</A
></DT
><DT
>11-9. <A
HREF="loops1.html#USERLIST"
>Listing all users on the system</A
></DT
><DT
>11-10. <A
HREF="loops1.html#FINDSTRING"
>Checking all the binaries in a directory for
authorship</A
></DT
><DT
>11-11. <A
HREF="loops1.html#SYMLINKS"
>Listing the <I
CLASS="FIRSTTERM"
>symbolic
links</I
> in a directory</A
></DT
><DT
>11-12. <A
HREF="loops1.html#SYMLINKS2"
>Symbolic links in a directory, saved to a file</A
></DT
><DT
>11-13. <A
HREF="loops1.html#FORLOOPC"
>A C-style <I
CLASS="FIRSTTERM"
>for</I
> loop</A
></DT
><DT
>11-14. <A
HREF="loops1.html#EX24"
>Using <I
CLASS="FIRSTTERM"
>efax</I
> in batch mode</A
></DT
><DT
>11-15. <A
HREF="loops1.html#EX25"
>Simple <I
CLASS="FIRSTTERM"
>while</I
> loop</A
></DT
><DT
>11-16. <A
HREF="loops1.html#EX26"
>Another <I
CLASS="FIRSTTERM"
>while</I
> loop</A
></DT
><DT
>11-17. <A
HREF="loops1.html#EX26A"
><I
CLASS="FIRSTTERM"
>while</I
> loop with multiple conditions</A
></DT
><DT
>11-18. <A
HREF="loops1.html#WHLOOPC"
>C-style syntax in a <I
CLASS="FIRSTTERM"
>while</I
> loop</A
></DT
><DT
>11-19. <A
HREF="loops1.html#EX27"
><I
CLASS="FIRSTTERM"
>until</I
> loop</A
></DT
><DT
>11-20. <A
HREF="nestedloops.html#NESTEDLOOP"
>Nested Loop</A
></DT
><DT
>11-21. <A
HREF="loopcontrol.html#EX28"
>Effects of <I
CLASS="FIRSTTERM"
>break</I
> and
<B
CLASS="COMMAND"
>continue</B
> in a loop</A
></DT
><DT
>11-22. <A
HREF="loopcontrol.html#BREAKLEVELS"
>Breaking out of multiple loop levels</A
></DT
><DT
>11-23. <A
HREF="loopcontrol.html#CONTINUELEVELS"
>Continuing at a higher loop level</A
></DT
><DT
>11-24. <A
HREF="loopcontrol.html#CONTINUENEX"
>Using <I
CLASS="FIRSTTERM"
>continue N</I
> in an actual task</A
></DT
><DT
>11-25. <A
HREF="testbranch.html#EX29"
>Using <I
CLASS="FIRSTTERM"
>case</I
></A
></DT
><DT
>11-26. <A
HREF="testbranch.html#EX30"
>Creating menus using <I
CLASS="FIRSTTERM"
>case</I
></A
></DT
><DT
>11-27. <A
HREF="testbranch.html#CASECMD"
>Using <I
CLASS="FIRSTTERM"
>command substitution</I
>
to generate the <I
CLASS="FIRSTTERM"
>case</I
> variable</A
></DT
><DT
>11-28. <A
HREF="testbranch.html#MATCHSTRING"
>Simple string matching</A
></DT
><DT
>11-29. <A
HREF="testbranch.html#ISALPHA"
>Checking for alphabetic input</A
></DT
><DT
>11-30. <A
HREF="testbranch.html#EX31"
>Creating menus using <I
CLASS="FIRSTTERM"
>select</I
></A
></DT
><DT
>11-31. <A
HREF="testbranch.html#EX32"
>Creating menus using <I
CLASS="FIRSTTERM"
>select</I
>
in a function</A
></DT
><DT
>12-1. <A
HREF="commandsub.html#STUPSCR"
>Stupid script tricks</A
></DT
><DT
>12-2. <A
HREF="commandsub.html#CSUBLOOP"
>Generating a variable from a loop</A
></DT
><DT
>12-3. <A
HREF="commandsub.html#AGRAM2"
>Finding anagrams</A
></DT
><DT
>15-1. <A
HREF="internal.html#SPAWNSCR"
>A script that spawns multiple instances of itself</A
></DT
><DT
>15-2. <A
HREF="internal.html#EX47"
><I
CLASS="FIRSTTERM"
>printf</I
> in action</A
></DT
><DT
>15-3. <A
HREF="internal.html#EX36"
>Variable assignment, using <I
CLASS="FIRSTTERM"
>read</I
></A
></DT
><DT
>15-4. <A
HREF="internal.html#READNOVAR"
>What happens when <I
CLASS="FIRSTTERM"
>read</I
> has no
variable</A
></DT
><DT
>15-5. <A
HREF="internal.html#READR"
>Multi-line input to <I
CLASS="FIRSTTERM"
>read</I
></A
></DT
><DT
>15-6. <A
HREF="internal.html#ARROWDETECT"
>Detecting the arrow keys</A
></DT
><DT
>15-7. <A
HREF="internal.html#READREDIR"
>Using <I
CLASS="FIRSTTERM"
>read</I
> with
<A
HREF="io-redirection.html#IOREDIRREF"
>file redirection</A
></A
></DT
><DT
>15-8. <A
HREF="internal.html#READPIPE"
>Problems reading from a pipe</A
></DT
><DT
>15-9. <A
HREF="internal.html#EX37"
>Changing the current working directory</A
></DT
><DT
>15-10. <A
HREF="internal.html#EX46"
>Letting <I
CLASS="FIRSTTERM"
>let</I
> do arithmetic.</A
></DT
><DT
>15-11. <A
HREF="internal.html#EX43"
>Showing the effect of <I
CLASS="FIRSTTERM"
>eval</I
></A
></DT
><DT
>15-12. <A
HREF="internal.html#ARRCHOICE"
>Using <I
CLASS="FIRSTTERM"
>eval</I
> to select
among variables</A
></DT
><DT
>15-13. <A
HREF="internal.html#ECHOPARAMS"
><I
CLASS="FIRSTTERM"
>Echoing</I
> the
<I
CLASS="FIRSTTERM"
>command-line parameters</I
></A
></DT
><DT
>15-14. <A
HREF="internal.html#EX44"
>Forcing a log-off</A
></DT
><DT
>15-15. <A
HREF="internal.html#ROT14"
>A version of <I
CLASS="FIRSTTERM"
>rot13</I
></A
></DT
><DT
>15-16. <A
HREF="internal.html#EX34"
>Using <I
CLASS="FIRSTTERM"
>set</I
> with positional
parameters</A
></DT
><DT
>15-17. <A
HREF="internal.html#REVPOSPARAMS"
>Reversing the positional parameters</A
></DT
><DT
>15-18. <A
HREF="internal.html#SETPOS"
>Reassigning the positional parameters</A
></DT
><DT
>15-19. <A
HREF="internal.html#UNS"
><SPAN
CLASS="QUOTE"
>"Unsetting"</SPAN
> a variable</A
></DT
><DT
>15-20. <A
HREF="internal.html#COLTOTALER3"
>Using <I
CLASS="FIRSTTERM"
>export</I
> to pass a variable to an
embedded <I
CLASS="FIRSTTERM"
>awk</I
> script</A
></DT
><DT
>15-21. <A
HREF="internal.html#EX33"
>Using <I
CLASS="FIRSTTERM"
>getopts</I
> to read the
options/arguments passed to a script</A
></DT
><DT
>15-22. <A
HREF="internal.html#EX38"
><SPAN
CLASS="QUOTE"
>"Including"</SPAN
> a data file</A
></DT
><DT
>15-23. <A
HREF="internal.html#SELFSOURCE"
>A (useless) script that sources itself</A
></DT
><DT
>15-24. <A
HREF="internal.html#EX54"
>Effects of <I
CLASS="FIRSTTERM"
>exec</I
></A
></DT
><DT
>15-25. <A
HREF="internal.html#SELFEXEC"
>A script that <I
CLASS="FIRSTTERM"
>exec's</I
> itself</A
></DT
><DT
>15-26. <A
HREF="x9644.html#EX39"
>Waiting for a process to finish before proceeding</A
></DT
><DT
>15-27. <A
HREF="x9644.html#SELFDESTRUCT"
>A script that kills itself</A
></DT
><DT
>16-1. <A
HREF="basic.html#EX40"
>Using <I
CLASS="FIRSTTERM"
>ls</I
> to create a table of contents
for burning a <SPAN
CLASS="ABBREV"
>CDR</SPAN
> disk</A
></DT
><DT
>16-2. <A
HREF="basic.html#HELLOL"
>Hello or Good-bye</A
></DT
><DT
>16-3. <A
HREF="moreadv.html#EX57"
><I
CLASS="FIRSTTERM"
>Badname</I
>, eliminate file names
in current directory containing bad characters and <A
HREF="special-chars.html#WHITESPACEREF"
>whitespace</A
>.</A
></DT
><DT
>16-4. <A
HREF="moreadv.html#IDELETE"
>Deleting a file by its <I
CLASS="FIRSTTERM"
>inode</I
>
number</A
></DT
><DT
>16-5. <A
HREF="moreadv.html#EX41"
>Logfile: Using <I
CLASS="FIRSTTERM"
>xargs</I
> to monitor system log</A
></DT
><DT
>16-6. <A
HREF="moreadv.html#EX42"
>Copying files in current directory to another</A
></DT
><DT
>16-7. <A
HREF="moreadv.html#KILLBYNAME"
>Killing processes by name</A
></DT
><DT
>16-8. <A
HREF="moreadv.html#WF2"
>Word frequency analysis using
<I
CLASS="FIRSTTERM"
>xargs</I
></A
></DT
><DT
>16-9. <A
HREF="moreadv.html#EX45"
>Using <I
CLASS="FIRSTTERM"
>expr</I
></A
></DT
><DT
>16-10. <A
HREF="timedate.html#EX51"
>Using <I
CLASS="FIRSTTERM"
>date</I
></A
></DT
><DT
>16-11. <A
HREF="timedate.html#DATECALC"
><I
CLASS="FIRSTTERM"
>Date</I
> calculations</A
></DT
><DT
>16-12. <A
HREF="textproc.html#WF"
>Word Frequency Analysis</A
></DT
><DT
>16-13. <A
HREF="textproc.html#SCRIPTDETECTOR"
>Which files are scripts?</A
></DT
><DT
>16-14. <A
HREF="textproc.html#RND"
>Generating 10-digit random numbers</A
></DT
><DT
>16-15. <A
HREF="textproc.html#EX12"
>Using <I
CLASS="FIRSTTERM"
>tail</I
> to monitor the system log</A
></DT
><DT
>16-16. <A
HREF="textproc.html#FROMSH"
>Printing out the <I
CLASS="FIRSTTERM"
>From</I
> lines in
stored e-mail messages</A
></DT
><DT
>16-17. <A
HREF="textproc.html#GRP"
>Emulating <I
CLASS="FIRSTTERM"
>grep</I
> in a script</A
></DT
><DT
>16-18. <A
HREF="textproc.html#CWSOLVER"
>Crossword puzzle solver</A
></DT
><DT
>16-19. <A
HREF="textproc.html#DICTLOOKUP"
>Looking up definitions in Webster's 1913 Dictionary</A
></DT
><DT
>16-20. <A
HREF="textproc.html#LOOKUP"
>Checking words in a list for validity</A
></DT
><DT
>16-21. <A
HREF="textproc.html#EX49"
><I
CLASS="FIRSTTERM"
>toupper</I
>: Transforms a file
to all uppercase.</A
></DT
><DT
>16-22. <A
HREF="textproc.html#LOWERCASE"
><I
CLASS="FIRSTTERM"
>lowercase</I
>: Changes all
filenames in working directory to lowercase.</A
></DT
><DT
>16-23. <A
HREF="textproc.html#DU"
><I
CLASS="FIRSTTERM"
>du</I
>: DOS to UNIX text file conversion.</A
></DT
><DT
>16-24. <A
HREF="textproc.html#ROT13"
><I
CLASS="FIRSTTERM"
>rot13</I
>: ultra-weak encryption.</A
></DT
><DT
>16-25. <A
HREF="textproc.html#CRYPTOQUOTE"
>Generating <SPAN
CLASS="QUOTE"
>"Crypto-Quote"</SPAN
> Puzzles</A
></DT
><DT
>16-26. <A
HREF="textproc.html#EX50"
>Formatted file listing.</A
></DT
><DT
>16-27. <A
HREF="textproc.html#COL"
>Using <I
CLASS="FIRSTTERM"
>column</I
> to format a directory
listing</A
></DT
><DT
>16-28. <A
HREF="textproc.html#LNUM"
><I
CLASS="FIRSTTERM"
>nl</I
>: A self-numbering script.</A
></DT
><DT
>16-29. <A
HREF="textproc.html#MANVIEW"
><I
CLASS="FIRSTTERM"
>manview</I
>: Viewing formatted manpages</A
></DT
><DT
>16-30. <A
HREF="filearchiv.html#EX48"
>Using <I
CLASS="FIRSTTERM"
>cpio</I
> to move a directory tree</A
></DT
><DT
>16-31. <A
HREF="filearchiv.html#DERPM"
>Unpacking an <I
CLASS="FIRSTTERM"
>rpm</I
> archive</A
></DT
><DT
>16-32. <A
HREF="filearchiv.html#STRIPC"
>Stripping comments from C program files</A
></DT
><DT
>16-33. <A
HREF="filearchiv.html#WHAT"
>Exploring <TT
CLASS="FILENAME"
>/usr/X11R6/bin</TT
></A
></DT
><DT
>16-34. <A
HREF="filearchiv.html#WSTRINGS"
>An <SPAN
CLASS="QUOTE"
>"improved"</SPAN
>
<I
CLASS="FIRSTTERM"
>strings</I
> command</A
></DT
><DT
>16-35. <A
HREF="filearchiv.html#FILECOMP"
>Using <I
CLASS="FIRSTTERM"
>cmp</I
> to compare two files
within a script.</A
></DT
><DT
>16-36. <A
HREF="filearchiv.html#EX35"
><I
CLASS="FIRSTTERM"
>basename</I
> and
<I
CLASS="FIRSTTERM"
>dirname</I
></A
></DT
><DT
>16-37. <A
HREF="filearchiv.html#SPLITCOPY"
>A script that copies itself in sections</A
></DT
><DT
>16-38. <A
HREF="filearchiv.html#FILEINTEGRITY"
>Checking file integrity</A
></DT
><DT
>16-39. <A
HREF="filearchiv.html#EX52"
>Uudecoding encoded files</A
></DT
><DT
>16-40. <A
HREF="communications.html#SPAMLOOKUP"
>Finding out where to report a spammer</A
></DT
><DT
>16-41. <A
HREF="communications.html#ISSPAMMER"
>Analyzing a spam domain</A
></DT
><DT
>16-42. <A
HREF="communications.html#QUOTEFETCH"
>Getting a stock quote</A
></DT
><DT
>16-43. <A
HREF="communications.html#FC4UPD"
>Updating FC4</A
></DT
><DT
>16-44. <A
HREF="communications.html#REMOTE"
>Using <I
CLASS="FIRSTTERM"
>ssh</I
></A
></DT
><DT
>16-45. <A
HREF="communications.html#SELFMAILER"
>A script that mails itself</A
></DT
><DT
>16-46. <A
HREF="mathc.html#PRIMES2"
>Generating prime numbers</A
></DT
><DT
>16-47. <A
HREF="mathc.html#MONTHLYPMT"
>Monthly Payment on a Mortgage</A
></DT
><DT
>16-48. <A
HREF="mathc.html#BASE"
>Base Conversion</A
></DT
><DT
>16-49. <A
HREF="mathc.html#ALTBC"
>Invoking <I
CLASS="FIRSTTERM"
>bc</I
> using a <I
CLASS="FIRSTTERM"
>here
document</I
></A
></DT
><DT
>16-50. <A
HREF="mathc.html#CANNON"
>Calculating PI</A
></DT
><DT
>16-51. <A
HREF="mathc.html#HEXCONVERT"
>Converting a decimal number to hexadecimal</A
></DT
><DT
>16-52. <A
HREF="mathc.html#FACTR"
>Factoring</A
></DT
><DT
>16-53. <A
HREF="mathc.html#HYPOT"
>Calculating the hypotenuse of a triangle</A
></DT
><DT
>16-54. <A
HREF="extmisc.html#EX53"
>Using <I
CLASS="FIRSTTERM"
>seq</I
> to generate loop
arguments</A
></DT
><DT
>16-55. <A
HREF="extmisc.html#LETTERCOUNT"
>Letter Count"</A
></DT
><DT
>16-56. <A
HREF="extmisc.html#EX33A"
>Using <I
CLASS="FIRSTTERM"
>getopt</I
> to parse command-line
options</A
></DT
><DT
>16-57. <A
HREF="extmisc.html#SELFCOPY"
>A script that copies itself</A
></DT
><DT
>16-58. <A
HREF="extmisc.html#EXERCISINGDD"
>Exercising <I
CLASS="FIRSTTERM"
>dd</I
></A
></DT
><DT
>16-59. <A
HREF="extmisc.html#DDKEYPRESS"
>Capturing Keystrokes</A
></DT
><DT
>16-60. <A
HREF="extmisc.html#RPSDCARD"
>Preparing a bootable SD card for the
<EM
>Raspberry Pi</EM
></A
></DT
><DT
>16-61. <A
HREF="extmisc.html#BLOTOUT"
>Securely deleting a file</A
></DT
><DT
>16-62. <A
HREF="extmisc.html#TEMPFILENAME"
>Filename generator</A
></DT
><DT
>16-63. <A
HREF="extmisc.html#UNITCONVERSION"
>Converting meters to miles</A
></DT
><DT
>16-64. <A
HREF="extmisc.html#M4"
>Using <I
CLASS="FIRSTTERM"
>m4</I
></A
></DT
><DT
>17-1. <A
HREF="system.html#SETNEWPW"
>Setting a new password</A
></DT
><DT
>17-2. <A
HREF="system.html#ERASE"
>Setting an <I
CLASS="FIRSTTERM"
>erase</I
> character</A
></DT
><DT
>17-3. <A
HREF="system.html#SECRETPW"
><I
CLASS="FIRSTTERM"
>secret password</I
>:
Turning off terminal echoing</A
></DT
><DT
>17-4. <A
HREF="system.html#KEYPRESS"
>Keypress detection</A
></DT
><DT
>17-5. <A
HREF="system.html#ISCAN"
>Checking a remote server for
<I
CLASS="FIRSTTERM"
>identd</I
></A
></DT
><DT
>17-6. <A
HREF="system.html#KILLPROCESS"
><I
CLASS="FIRSTTERM"
>pidof</I
> helps kill a process</A
></DT
><DT
>17-7. <A
HREF="system.html#ISOMOUNTREF"
>Checking a CD image</A
></DT
><DT
>17-8. <A
HREF="system.html#CREATEFS"
>Creating a filesystem in a file</A
></DT
><DT
>17-9. <A
HREF="system.html#ADDDRV"
>Adding a new hard drive</A
></DT
><DT
>17-10. <A
HREF="system.html#ROT13A"
>Using <I
CLASS="FIRSTTERM"
>umask</I
> to hide an output file
from prying eyes</A
></DT
><DT
>17-11. <A
HREF="system.html#BACKLIGHT"
><I
CLASS="FIRSTTERM"
>Backlight</I
>: changes
the brightness of the (laptop) screen backlight</A
></DT
><DT
>17-12. <A
HREF="sysscripts.html#EX55"
><I
CLASS="FIRSTTERM"
>killall</I
>, from <TT
CLASS="FILENAME"
>/etc/rc.d/init.d</TT
></A
></DT
><DT
>19-1. <A
HREF="here-docs.html#EX70"
><I
CLASS="FIRSTTERM"
>broadcast</I
>: Sends message to everyone
logged in</A
></DT
><DT
>19-2. <A
HREF="here-docs.html#EX69"
><I
CLASS="FIRSTTERM"
>dummyfile</I
>: Creates a 2-line dummy
file</A
></DT
><DT
>19-3. <A
HREF="here-docs.html#EX71"
>Multi-line message using <I
CLASS="FIRSTTERM"
>cat</I
></A
></DT
><DT
>19-4. <A
HREF="here-docs.html#EX71A"
>Multi-line message, with tabs suppressed</A
></DT
><DT
>19-5. <A
HREF="here-docs.html#EX71B"
>Here document with replaceable parameters</A
></DT
><DT
>19-6. <A
HREF="here-docs.html#EX72"
>Upload a file pair to <I
CLASS="FIRSTTERM"
>Sunsite</I
> incoming
directory</A
></DT
><DT
>19-7. <A
HREF="here-docs.html#EX71C"
>Parameter substitution turned off</A
></DT
><DT
>19-8. <A
HREF="here-docs.html#GENERATESCRIPT"
>A script that generates another script</A
></DT
><DT
>19-9. <A
HREF="here-docs.html#HF"
>Here documents and functions</A
></DT
><DT
>19-10. <A
HREF="here-docs.html#ANONHEREDOC"
><SPAN
CLASS="QUOTE"
>"Anonymous"</SPAN
> Here Document</A
></DT
><DT
>19-11. <A
HREF="here-docs.html#COMMENTBLOCK"
>Commenting out a block of code</A
></DT
><DT
>19-12. <A
HREF="here-docs.html#SELFDOCUMENT"
>A self-documenting script</A
></DT
><DT
>19-13. <A
HREF="x17837.html#PREPENDEX"
>Prepending a line to a file</A
></DT
><DT
>19-14. <A
HREF="x17837.html#MAILBOXGREP"
>Parsing a mailbox</A
></DT
><DT
>20-1. <A
HREF="x17974.html#REDIR1"
>Redirecting <TT
CLASS="FILENAME"
>stdin</TT
> using
<I
CLASS="FIRSTTERM"
>exec</I
></A
></DT
><DT
>20-2. <A
HREF="x17974.html#REASSIGNSTDOUT"
>Redirecting <TT
CLASS="FILENAME"
>stdout</TT
> using
<I
CLASS="FIRSTTERM"
>exec</I
></A
></DT
><DT
>20-3. <A
HREF="x17974.html#UPPERCONV"
>Redirecting both <TT
CLASS="FILENAME"
>stdin</TT
> and
<TT
CLASS="FILENAME"
>stdout</TT
> in the same script with
<I
CLASS="FIRSTTERM"
>exec</I
></A
></DT
><DT
>20-4. <A
HREF="x17974.html#AVOIDSUBSHELL"
>Avoiding a subshell</A
></DT
><DT
>20-5. <A
HREF="redircb.html#REDIR2"
>Redirected <I
CLASS="FIRSTTERM"
>while</I
> loop</A
></DT
><DT
>20-6. <A
HREF="redircb.html#REDIR2A"
>Alternate form of redirected <I
CLASS="FIRSTTERM"
>while</I
> loop</A
></DT
><DT
>20-7. <A
HREF="redircb.html#REDIR3"
>Redirected <I
CLASS="FIRSTTERM"
>until</I
> loop</A
></DT
><DT
>20-8. <A
HREF="redircb.html#REDIR4"
>Redirected <I
CLASS="FIRSTTERM"
>for</I
> loop</A
></DT
><DT
>20-9. <A
HREF="redircb.html#REDIR4A"
>Redirected <I
CLASS="FIRSTTERM"
>for</I
> loop (both
<TT
CLASS="FILENAME"
>stdin</TT
> and <TT
CLASS="FILENAME"
>stdout</TT
>
redirected)</A
></DT
><DT
>20-10. <A
HREF="redircb.html#REDIR5"
>Redirected <I
CLASS="FIRSTTERM"
>if/then</I
> test</A
></DT
><DT
>20-11. <A
HREF="redircb.html#NAMESDATA"
>Data file <I
CLASS="FIRSTTERM"
>names.data</I
> for above
examples</A
></DT
><DT
>20-12. <A
HREF="redirapps.html#LOGEVENTS"
>Logging events</A
></DT
><DT
>21-1. <A
HREF="subshells.html#SUBSHELL"
>Variable scope in a subshell</A
></DT
><DT
>21-2. <A
HREF="subshells.html#ALLPROFS"
>List User Profiles</A
></DT
><DT
>21-3. <A
HREF="subshells.html#PARALLEL-PROCESSES"
>Running parallel processes in subshells</A
></DT
><DT
>22-1. <A
HREF="restricted-sh.html#RESTRICTED"
>Running a script in restricted mode</A
></DT
><DT
>23-1. <A
HREF="process-sub.html#WRPS"
>Code block redirection without forking</A
></DT
><DT
>23-2. <A
HREF="process-sub.html#PSUBP"
>Redirecting the output of <I
CLASS="FIRSTTERM"
>process
substitution</I
> into a loop.</A
></DT
><DT
>24-1. <A
HREF="functions.html#EX59"
>Simple functions</A
></DT
><DT
>24-2. <A
HREF="complexfunct.html#EX60"
>Function Taking Parameters</A
></DT
><DT
>24-3. <A
HREF="complexfunct.html#FUNCCMDLINEARG"
>Functions and command-line args passed to the script</A
></DT
><DT
>24-4. <A
HREF="complexfunct.html#INDFUNC"
>Passing an indirect reference to a function</A
></DT
><DT
>24-5. <A
HREF="complexfunct.html#DEREFERENCECL"
>Dereferencing a parameter passed to a function</A
></DT
><DT
>24-6. <A
HREF="complexfunct.html#REFPARAMS"
>Again, dereferencing a parameter passed to a function</A
></DT
><DT
>24-7. <A
HREF="complexfunct.html#MAX"
>Maximum of two numbers</A
></DT
><DT
>24-8. <A
HREF="complexfunct.html#EX61"
>Converting numbers to Roman numerals</A
></DT
><DT
>24-9. <A
HREF="complexfunct.html#RETURNTEST"
>Testing large return values in a function</A
></DT
><DT
>24-10. <A
HREF="complexfunct.html#MAX2"
>Comparing two large integers</A
></DT
><DT
>24-11. <A
HREF="complexfunct.html#REALNAME"
>Real name from username</A
></DT
><DT
>24-12. <A
HREF="localvar.html#EX62"
>Local variable visibility</A
></DT
><DT
>24-13. <A
HREF="localvar.html#RECURSIONDEMO"
>Demonstration of a simple recursive function</A
></DT
><DT
>24-14. <A
HREF="localvar.html#RECURSIONDEMO2"
>Another simple demonstration</A
></DT
><DT
>24-15. <A
HREF="localvar.html#EX63"
>Recursion, using a local variable</A
></DT
><DT
>24-16. <A
HREF="recurnolocvar.html#FIBO"
><I
CLASS="FIRSTTERM"
>The Fibonacci Sequence</I
></A
></DT
><DT
>24-17. <A
HREF="recurnolocvar.html#HANOI"
><I
CLASS="FIRSTTERM"
>The Towers of Hanoi</I
></A
></DT
><DT
>25-1. <A
HREF="aliases.html#AL"
>Aliases within a script</A
></DT
><DT
>25-2. <A
HREF="aliases.html#UNAL"
><I
CLASS="FIRSTTERM"
>unalias</I
>: Setting and unsetting
an alias</A
></DT
><DT
>26-1. <A
HREF="list-cons.html#EX64"
>Using an <I
CLASS="FIRSTTERM"
>and list</I
> to test
for command-line arguments</A
></DT
><DT
>26-2. <A
HREF="list-cons.html#ANDLIST2"
>Another command-line arg test using an <I
CLASS="FIRSTTERM"
>and
list</I
></A
></DT
><DT
>26-3. <A
HREF="list-cons.html#EX65"
>Using <I
CLASS="FIRSTTERM"
>or lists</I
> in combination
with an <I
CLASS="FIRSTTERM"
>and list</I
></A
></DT
><DT
>27-1. <A
HREF="arrays.html#EX66"
>Simple array usage</A
></DT
><DT
>27-2. <A
HREF="arrays.html#POEM"
>Formatting a poem</A
></DT
><DT
>27-3. <A
HREF="arrays.html#ARRAYOPS"
>Various array operations</A
></DT
><DT
>27-4. <A
HREF="arrays.html#ARRAYSTROPS"
>String operations on arrays</A
></DT
><DT
>27-5. <A
HREF="arrays.html#SCRIPTARRAY"
>Loading the contents of a script into an array</A
></DT
><DT
>27-6. <A
HREF="arrays.html#EX67"
>Some special properties of arrays</A
></DT
><DT
>27-7. <A
HREF="arrays.html#EMPTYARRAY"
>Of empty arrays and empty elements</A
></DT
><DT
>27-8. <A
HREF="arrays.html#ARRAYASSIGN"
>Initializing arrays</A
></DT
><DT
>27-9. <A
HREF="arrays.html#COPYARRAY"
>Copying and concatenating arrays</A
></DT
><DT
>27-10. <A
HREF="arrays.html#ARRAYAPPEND"
>More on concatenating arrays</A
></DT
><DT
>27-11. <A
HREF="arrays.html#BUBBLE"
>The Bubble Sort</A
></DT
><DT
>27-12. <A
HREF="arrays.html#EMBARR"
>Embedded arrays and indirect references</A
></DT
><DT
>27-13. <A
HREF="arrays.html#EX68"
>The Sieve of Eratosthenes</A
></DT
><DT
>27-14. <A
HREF="arrays.html#EX68A"
>The Sieve of Eratosthenes, Optimized</A
></DT
><DT
>27-15. <A
HREF="arrays.html#STACKEX"
>Emulating a push-down stack</A
></DT
><DT
>27-16. <A
HREF="arrays.html#QFUNCTION"
>Complex array application:
<EM
>Exploring a weird mathematical series</EM
></A
></DT
><DT
>27-17. <A
HREF="arrays.html#TWODIM"
>Simulating a two-dimensional array, then tilting it</A
></DT
><DT
>28-1. <A
HREF="ivr.html#INDREF"
>Indirect Variable References</A
></DT
><DT
>28-2. <A
HREF="ivr.html#COLTOTALER2"
>Passing an indirect reference to <I
CLASS="FIRSTTERM"
>awk</I
></A
></DT
><DT
>29-1. <A
HREF="devref1.html#DEVTCP"
>Using <TT
CLASS="FILENAME"
>/dev/tcp</TT
> for
troubleshooting</A
></DT
><DT
>29-2. <A
HREF="devref1.html#MUSICSCR"
>Playing music</A
></DT
><DT
>29-3. <A
HREF="procref1.html#PIDID"
>Finding the process associated with a PID</A
></DT
><DT
>29-4. <A
HREF="procref1.html#CONSTAT"
>On-line connect status</A
></DT
><DT
>30-1. <A
HREF="networkprogramming.html#TESTCGI"
>Print the server environment</A
></DT
><DT
>30-2. <A
HREF="networkprogramming.html#IPADDRESSES"
>IP addresses</A
></DT
><DT
>31-1. <A
HREF="zeros.html#COOKIES"
>Hiding the cookie jar</A
></DT
><DT
>31-2. <A
HREF="zeros.html#EX73"
>Setting up a swapfile using <TT
CLASS="FILENAME"
>/dev/zero</TT
></A
></DT
><DT
>31-3. <A
HREF="zeros.html#RAMDISK"
>Creating a ramdisk</A
></DT
><DT
>32-1. <A
HREF="debugging.html#EX74"
>A buggy script</A
></DT
><DT
>32-2. <A
HREF="debugging.html#MISSINGKEYWORD"
>Missing <A
HREF="internal.html#KEYWORDREF"
>keyword</A
></A
></DT
><DT
>32-3. <A
HREF="debugging.html#EX75"
><I
CLASS="FIRSTTERM"
>test24</I
>: another buggy script</A
></DT
><DT
>32-4. <A
HREF="debugging.html#ASSERT"
>Testing a condition with an
<I
CLASS="FIRSTTERM"
>assert</I
></A
></DT
><DT
>32-5. <A
HREF="debugging.html#EX76"
>Trapping at exit</A
></DT
><DT
>32-6. <A
HREF="debugging.html#ONLINE"
>Cleaning up after <B
CLASS="KEYCAP"
>Control-C</B
></A
></DT
><DT
>32-7. <A
HREF="debugging.html#PROGRESSBAR2"
>A Simple Implementation of a Progress Bar</A
></DT
><DT
>32-8. <A
HREF="debugging.html#VARTRACE"
>Tracing a variable</A
></DT
><DT
>32-9. <A
HREF="debugging.html#MULTIPLEPROC"
>Running multiple processes (on an SMP box)</A
></DT
><DT
>34-1. <A
HREF="gotchas.html#BADOP"
>Numerical and string comparison are not equivalent</A
></DT
><DT
>34-2. <A
HREF="gotchas.html#SUBPIT"
>Subshell Pitfalls</A
></DT
><DT
>34-3. <A
HREF="gotchas.html#BADREAD"
>Piping the output of <I
CLASS="FIRSTTERM"
>echo</I
> to a
<I
CLASS="FIRSTTERM"
>read</I
></A
></DT
><DT
>36-1. <A
HREF="wrapper.html#EX3"
><I
CLASS="FIRSTTERM"
>shell wrapper</I
></A
></DT
><DT
>36-2. <A
HREF="wrapper.html#EX4"
>A slightly more complex <I
CLASS="FIRSTTERM"
>shell
wrapper</I
></A
></DT
><DT
>36-3. <A
HREF="wrapper.html#LOGGINGWRAPPER"
>A generic <I
CLASS="FIRSTTERM"
>shell wrapper</I
> that
writes to a logfile</A
></DT
><DT
>36-4. <A
HREF="wrapper.html#PRASC"
>A <I
CLASS="FIRSTTERM"
>shell wrapper</I
> around an awk
script</A
></DT
><DT
>36-5. <A
HREF="wrapper.html#COLTOTALER"
>A <I
CLASS="FIRSTTERM"
>shell wrapper</I
> around another
awk script</A
></DT
><DT
>36-6. <A
HREF="wrapper.html#EX56"
>Perl embedded in a <I
CLASS="FIRSTTERM"
>Bash</I
> script</A
></DT
><DT
>36-7. <A
HREF="wrapper.html#BASHANDPERL"
>Bash and Perl scripts combined</A
></DT
><DT
>36-8. <A
HREF="wrapper.html#EX56PY"
>Python embedded in a <I
CLASS="FIRSTTERM"
>Bash</I
> script</A
></DT
><DT
>36-9. <A
HREF="wrapper.html#SPEECH0"
>A script that speaks</A
></DT
><DT
>36-10. <A
HREF="recursionsct.html#RECURSE"
>A (useless) script that recursively calls itself</A
></DT
><DT
>36-11. <A
HREF="recursionsct.html#PBOOK"
>A (useful) script that recursively calls itself</A
></DT
><DT
>36-12. <A
HREF="recursionsct.html#USRMNT"
>Another (useful) script that recursively calls itself</A
></DT
><DT
>36-13. <A
HREF="colorizing.html#EX30A"
>A <SPAN
CLASS="QUOTE"
>"colorized"</SPAN
> address database</A
></DT
><DT
>36-14. <A
HREF="colorizing.html#DRAW-BOX"
>Drawing a box</A
></DT
><DT
>36-15. <A
HREF="colorizing.html#COLORECHO"
>Echoing colored text</A
></DT
><DT
>36-16. <A
HREF="colorizing.html#HORSERACE"
>A <SPAN
CLASS="QUOTE"
>"horserace"</SPAN
> game</A
></DT
><DT
>36-17. <A
HREF="assortedtips.html#PROGRESSBAR"
>A Progress Bar</A
></DT
><DT
>36-18. <A
HREF="assortedtips.html#MULTIPLICATION"
>Return value trickery</A
></DT
><DT
>36-19. <A
HREF="assortedtips.html#SUMPRODUCT"
>Even more return value trickery</A
></DT
><DT
>36-20. <A
HREF="assortedtips.html#ARRFUNC"
>Passing and returning arrays</A
></DT
><DT
>36-21. <A
HREF="assortedtips.html#AGRAM"
>Fun with anagrams</A
></DT
><DT
>36-22. <A
HREF="assortedtips.html#DIALOG"
>Widgets invoked from a shell script</A
></DT
><DT
>36-23. <A
HREF="portabilityissues.html#TESTSUITE"
>Test Suite</A
></DT
><DT
>37-1. <A
HREF="bashver2.html#EX77"
>String expansion</A
></DT
><DT
>37-2. <A
HREF="bashver2.html#EX78"
>Indirect variable references - the new way</A
></DT
><DT
>37-3. <A
HREF="bashver2.html#RESISTOR"
>Simple database application, using indirect variable
referencing</A
></DT
><DT
>37-4. <A
HREF="bashver2.html#CARDS"
>Using arrays and other miscellaneous trickery
to deal four random hands from a deck of cards</A
></DT
><DT
>37-5. <A
HREF="bashver4.html#FETCHADDRESS"
>A simple address database</A
></DT
><DT
>37-6. <A
HREF="bashver4.html#FETCHADDRESS2"
>A somewhat more elaborate address database</A
></DT
><DT
>37-7. <A
HREF="bashver4.html#CASE4"
>Testing characters</A
></DT
><DT
>37-8. <A
HREF="bashver4.html#READN"
>Reading N characters</A
></DT
><DT
>37-9. <A
HREF="bashver4.html#HERECOMMSUB"
>Using a <I
CLASS="FIRSTTERM"
>here document</I
>
to set a variable</A
></DT
><DT
>37-10. <A
HREF="bashver4.html#LASTPIPEOPT"
>Piping input to a <A
HREF="internal.html#READREF"
>read</A
></A
></DT
><DT
>37-11. <A
HREF="bashver4.html#NEGARRAY"
>Negative array indices</A
></DT
><DT
>37-12. <A
HREF="bashver4.html#NEGOFFSET"
>Negative parameter in string-extraction
construct</A
></DT
><DT
>A-1. <A
HREF="contributed-scripts.html#MAILFORMAT"
><I
CLASS="FIRSTTERM"
>mailformat</I
>: Formatting an e-mail
message</A
></DT
><DT
>A-2. <A
HREF="contributed-scripts.html#RN"
><I
CLASS="FIRSTTERM"
>rn</I
>: A simple-minded file renaming
utility</A
></DT
><DT
>A-3. <A
HREF="contributed-scripts.html#BLANKRENAME"
><I
CLASS="FIRSTTERM"
>blank-rename</I
>: Renames filenames containing
blanks</A
></DT
><DT
>A-4. <A
HREF="contributed-scripts.html#ENCRYPTEDPW"
><I
CLASS="FIRSTTERM"
>encryptedpw</I
>: Uploading to an ftp site,
using a locally encrypted password</A
></DT
><DT
>A-5. <A
HREF="contributed-scripts.html#COPYCD"
><I
CLASS="FIRSTTERM"
>copy-cd</I
>: Copying a data CD</A
></DT
><DT
>A-6. <A
HREF="contributed-scripts.html#COLLATZ"
>Collatz series</A
></DT
><DT
>A-7. <A
HREF="contributed-scripts.html#DAYSBETWEEN"
><I
CLASS="FIRSTTERM"
>days-between</I
>: Days between two
dates</A
></DT
><DT
>A-8. <A
HREF="contributed-scripts.html#MAKEDICT"
>Making a <I
CLASS="FIRSTTERM"
>dictionary</I
></A
></DT
><DT
>A-9. <A
HREF="contributed-scripts.html#SOUNDEX"
>Soundex conversion</A
></DT
><DT
>A-10. <A
HREF="contributed-scripts.html#LIFESLOW"
><I
CLASS="FIRSTTERM"
>Game of Life</I
></A
></DT
><DT
>A-11. <A
HREF="contributed-scripts.html#GEN0DATA"
>Data file for <I
CLASS="FIRSTTERM"
>Game of Life</I
></A
></DT
><DT
>A-12. <A
HREF="contributed-scripts.html#BEHEAD"
><I
CLASS="FIRSTTERM"
>behead</I
>: Removing mail and news
message headers</A
></DT
><DT
>A-13. <A
HREF="contributed-scripts.html#PW"
><I
CLASS="FIRSTTERM"
>password</I
>: Generating random
8-character passwords</A
></DT
><DT
>A-14. <A
HREF="contributed-scripts.html#FIFO"
><I
CLASS="FIRSTTERM"
>fifo</I
>: Making daily backups, using
named pipes</A
></DT
><DT
>A-15. <A
HREF="contributed-scripts.html#PRIMES"
>Generating prime numbers using the modulo operator</A
></DT
><DT
>A-16. <A
HREF="contributed-scripts.html#TREE"
><I
CLASS="FIRSTTERM"
>tree</I
>: Displaying a directory tree</A
></DT
><DT
>A-17. <A
HREF="contributed-scripts.html#TREE2"
><I
CLASS="FIRSTTERM"
>tree2</I
>: Alternate directory tree script</A
></DT
><DT
>A-18. <A
HREF="contributed-scripts.html#STRING"
><I
CLASS="FIRSTTERM"
>string functions</I
>: C-style string
functions</A
></DT
><DT
>A-19. <A
HREF="contributed-scripts.html#DIRECTORYINFO"
>Directory information</A
></DT
><DT
>A-20. <A
HREF="contributed-scripts.html#HASHLIB"
>Library of hash functions</A
></DT
><DT
>A-21. <A
HREF="contributed-scripts.html#HASHEXAMPLE"
>Colorizing text using hash functions</A
></DT
><DT
>A-22. <A
HREF="contributed-scripts.html#HASHEX2"
>More on hash functions</A
></DT
><DT
>A-23. <A
HREF="contributed-scripts.html#USBINST"
>Mounting USB keychain storage devices</A
></DT
><DT
>A-24. <A
HREF="contributed-scripts.html#TOHTML"
>Converting to HTML</A
></DT
><DT
>A-25. <A
HREF="contributed-scripts.html#ARCHIVWEBLOGS"
>Preserving weblogs</A
></DT
><DT
>A-26. <A
HREF="contributed-scripts.html#PROTECTLITERAL"
>Protecting literal strings</A
></DT
><DT
>A-27. <A
HREF="contributed-scripts.html#UNPROTECTLITERAL"
>Unprotecting literal strings</A
></DT
><DT
>A-28. <A
HREF="contributed-scripts.html#ISSPAMMER2"
>Spammer Identification</A
></DT
><DT
>A-29. <A
HREF="contributed-scripts.html#WHX"
>Spammer Hunt</A
></DT
><DT
>A-30. <A
HREF="contributed-scripts.html#WGETTER2"
>Making <I
CLASS="FIRSTTERM"
>wget</I
> easier to use</A
></DT
><DT
>A-31. <A
HREF="contributed-scripts.html#BASHPODDER"
>A <I
CLASS="FIRSTTERM"
>podcasting</I
> script</A
></DT
><DT
>A-32. <A
HREF="contributed-scripts.html#NIGHTLYBACKUP"
>Nightly backup to a firewire HD</A
></DT
><DT
>A-33. <A
HREF="contributed-scripts.html#CDLL"
>An expanded <I
CLASS="FIRSTTERM"
>cd</I
> command</A
></DT
><DT
>A-34. <A
HREF="contributed-scripts.html#SOUNDCARDON"
>A soundcard setup script</A
></DT
><DT
>A-35. <A
HREF="contributed-scripts.html#FINDSPLIT"
>Locating split paragraphs in a text file</A
></DT
><DT
>A-36. <A
HREF="contributed-scripts.html#INSERTIONSORT"
>Insertion sort</A
></DT
><DT
>A-37. <A
HREF="contributed-scripts.html#STDDEV"
>Standard Deviation</A
></DT
><DT
>A-38. <A
HREF="contributed-scripts.html#PADSW"
>A <I
CLASS="FIRSTTERM"
>pad</I
> file generator for shareware
authors</A
></DT
><DT
>A-39. <A
HREF="contributed-scripts.html#MANED"
>A <I
CLASS="FIRSTTERM"
>man page</I
> editor</A
></DT
><DT
>A-40. <A
HREF="contributed-scripts.html#PETALS"
>Petals Around the Rose</A
></DT
><DT
>A-41. <A
HREF="contributed-scripts.html#QKY"
>Quacky: a Perquackey-type word game</A
></DT
><DT
>A-42. <A
HREF="contributed-scripts.html#NIM"
>Nim</A
></DT
><DT
>A-43. <A
HREF="contributed-scripts.html#STOPWATCH"
>A command-line stopwatch</A
></DT
><DT
>A-44. <A
HREF="contributed-scripts.html#HOMEWORK"
>An all-purpose shell scripting homework assignment solution</A
></DT
><DT
>A-45. <A
HREF="contributed-scripts.html#KTOUR"
>The Knight's Tour</A
></DT
><DT
>A-46. <A
HREF="contributed-scripts.html#MSQUARE"
>Magic Squares</A
></DT
><DT
>A-47. <A
HREF="contributed-scripts.html#FIFTEEN"
>Fifteen Puzzle</A
></DT
><DT
>A-48. <A
HREF="contributed-scripts.html#HANOI2"
><I
CLASS="FIRSTTERM"
>The Towers of Hanoi, graphic
version</I
></A
></DT
><DT
>A-49. <A
HREF="contributed-scripts.html#HANOI2A"
><I
CLASS="FIRSTTERM"
>The Towers of Hanoi, alternate graphic
version</I
></A
></DT
><DT
>A-50. <A
HREF="contributed-scripts.html#USEGETOPT"
>An alternate version of the
<A
HREF="string-manipulation.html#GETOPTSIMPLE"
>getopt-simple.sh</A
> script</A
></DT
><DT
>A-51. <A
HREF="contributed-scripts.html#USEGETOPT2"
>The version of the
<I
CLASS="FIRSTTERM"
>UseGetOpt.sh</I
> example used in the <A
HREF="tabexpansion.html"
>Tab Expansion appendix</A
></A
></DT
><DT
>A-52. <A
HREF="contributed-scripts.html#SHOWALLC"
>Cycling through all the possible color backgrounds</A
></DT
><DT
>A-53. <A
HREF="contributed-scripts.html#SAMORSE"
>Morse Code Practice</A
></DT
><DT
>A-54. <A
HREF="contributed-scripts.html#BASE64"
>Base64 encoding/decoding</A
></DT
><DT
>A-55. <A
HREF="contributed-scripts.html#SEDAPPEND"
>Inserting text in a file using
<I
CLASS="FIRSTTERM"
>sed</I
></A
></DT
><DT
>A-56. <A
HREF="contributed-scripts.html#GRONSFELD"
>The Gronsfeld Cipher</A
></DT
><DT
>A-57. <A
HREF="contributed-scripts.html#BINGO"
>Bingo Number Generator</A
></DT
><DT
>A-58. <A
HREF="contributed-scripts.html#BASICSREVIEWED"
>Basics Reviewed</A
></DT
><DT
>A-59. <A
HREF="contributed-scripts.html#TESTEXECTIME"
>Testing execution times of various commands</A
></DT
><DT
>A-60. <A
HREF="contributed-scripts.html#ASSOCARRTEST"
>Associative arrays vs. conventional arrays (execution
times)</A
></DT
><DT
>C-1. <A
HREF="awk.html#LETTERCOUNT2"
>Counting Letter Occurrences</A
></DT
><DT
>J-1. <A
HREF="tabexpansion.html#USEGETOPTEX"
>Completion script for
<I
CLASS="FIRSTTERM"
>UseGetOpt.sh</I
></A
></DT
><DT
>M-1. <A
HREF="sample-bashrc.html#BASHRC"
>Sample <TT
CLASS="FILENAME"
>.bashrc</TT
> file</A
></DT
><DT
>M-2. <A
HREF="sample-bashrc.html#BASHPROF"
><TT
CLASS="FILENAME"
>.bash_profile</TT
> file</A
></DT
><DT
>N-1. <A
HREF="dosbatch.html#VIEWDAT"
>VIEWDATA.BAT: DOS Batch File</A
></DT
><DT
>N-2. <A
HREF="dosbatch.html#VIEWDATA"
><I
CLASS="FIRSTTERM"
>viewdata.sh</I
>: Shell Script Conversion
of VIEWDATA.BAT</A
></DT
><DT
>T-1. <A
HREF="asciitable.html#ASCIISH"
>A script that generates an ASCII table</A
></DT
><DT
>T-2. <A
HREF="asciitable.html#ASCII2SH"
>Another ASCII table script</A
></DT
><DT
>T-3. <A
HREF="asciitable.html#ASCII3SH"
>A third ASCII table script, using
<I
CLASS="FIRSTTERM"
>awk</I
></A
></DT
></DL
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