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<!DOCTYPE HTML>
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<title>Shell Variables | Introduction</title>
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<div class="book"
data-level="17"
data-chapter-title="Shell Variables"
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<ul class="summary">
<li class="chapter " data-level="0" data-path="index.html">
<a href="./index.html">
<i class="fa fa-check"></i>
Introduction
</a>
</li>
<li class="chapter " data-level="1" data-path="bug_reports.html">
<a href="./bug_reports.html">
<i class="fa fa-check"></i>
<b>1.</b>
Bug reports
</a>
</li>
<li class="chapter " data-level="2" data-path="basics.html">
<a href="./basics.html">
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<b>2.</b>
Basics
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<ul class="articles">
<li class="chapter " data-level="2.1" data-path="quotes.html">
<a href="./quotes.html">
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<b>2.1.</b>
Quotes
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<li class="chapter " data-level="2.1.1" data-path="escape_sequences.html">
<a href="./escape_sequences.html">
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<b>2.1.1.</b>
Escape Sequences
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</ul>
</li>
<li class="chapter " data-level="2.2" data-path="variables.html">
<a href="./variables.html">
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<b>2.2.</b>
Variables
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</li>
<li class="chapter " data-level="2.3" data-path="functions.html">
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<b>2.3.</b>
Functions
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</li>
<li class="chapter " data-level="2.4" data-path="exit_status.html">
<a href="./exit_status.html">
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<b>2.4.</b>
Exit Status
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<li class="chapter " data-level="2.5" data-path="pattern_matching.html">
<a href="./pattern_matching.html">
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<b>2.5.</b>
Pattern Matching
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</li>
<li class="chapter " data-level="2.6" data-path="shebang.html">
<a href="./shebang.html">
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<b>2.6.</b>
#!
</a>
</li>
<li class="chapter " data-level="2.7" data-path="interactive_non-interactive.html">
<a href="./interactive_non-interactive.html">
<i class="fa fa-check"></i>
<b>2.7.</b>
Interactive vs Non-Interactive Shell
</a>
</li>
<li class="chapter " data-level="2.8" data-path="login_non-login.html">
<a href="./login_non-login.html">
<i class="fa fa-check"></i>
<b>2.8.</b>
Login vs Non-Login Shell
</a>
</li>
<li class="chapter " data-level="2.9" data-path="etc.html">
<a href="./etc.html">
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<b>2.9.</b>
etc
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</li>
</ul>
</li>
<li class="chapter " data-level="3" data-path="test.html">
<a href="./test.html">
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<b>3.</b>
Test
</a>
<ul class="articles">
<li class="chapter " data-level="3.1" data-path="test_operators.html">
<a href="./test_operators.html">
<i class="fa fa-check"></i>
<b>3.1.</b>
Operators
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4" data-path="subshells.html">
<a href="./subshells.html">
<i class="fa fa-check"></i>
<b>4.</b>
Subshells
</a>
<ul class="articles">
<li class="chapter " data-level="4.1" data-path="process_creation.html">
<a href="./process_creation.html">
<i class="fa fa-check"></i>
<b>4.1.</b>
Process Creation
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5" data-path="commands.html">
<a href="./commands.html">
<i class="fa fa-check"></i>
<b>5.</b>
Commands
</a>
<ul class="articles">
<li class="chapter " data-level="5.1" data-path="builtin_commands.html">
<a href="./builtin_commands.html">
<i class="fa fa-check"></i>
<b>5.1.</b>
Builtin Commands
</a>
<ul class="articles">
<li class="chapter " data-level="5.1.1" data-path="read.html">
<a href="./read.html">
<i class="fa fa-check"></i>
<b>5.1.1.</b>
read
</a>
</li>
<li class="chapter " data-level="5.1.2" data-path="printf.html">
<a href="./printf.html">
<i class="fa fa-check"></i>
<b>5.1.2.</b>
printf
</a>
</li>
<li class="chapter " data-level="5.1.3" data-path="eval.html">
<a href="./eval.html">
<i class="fa fa-check"></i>
<b>5.1.3.</b>
eval
</a>
</li>
<li class="chapter " data-level="5.1.4" data-path="getopts.html">
<a href="./getopts.html">
<i class="fa fa-check"></i>
<b>5.1.4.</b>
getopts
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5.2" data-path="keyword_commands.html">
<a href="./keyword_commands.html">
<i class="fa fa-check"></i>
<b>5.2.</b>
Keyword Commands
</a>
<ul class="articles">
<li class="chapter " data-level="5.2.1" data-path="compound_commands.html">
<a href="./compound_commands.html">
<i class="fa fa-check"></i>
<b>5.2.1.</b>
Compound Commands
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5.3" data-path="special_commands.html">
<a href="./special_commands.html">
<i class="fa fa-check"></i>
<b>5.3.</b>
Special Commands
</a>
</li>
<li class="chapter " data-level="5.4" data-path="expr.html">
<a href="./expr.html">
<i class="fa fa-check"></i>
<b>5.4.</b>
expr
</a>
</li>
<li class="chapter " data-level="5.5" data-path="grep.html">
<a href="./grep.html">
<i class="fa fa-check"></i>
<b>5.5.</b>
grep
</a>
</li>
<li class="chapter " data-level="5.6" data-path="find.html">
<a href="./find.html">
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<b>5.6.</b>
find
</a>
</li>
<li class="chapter " data-level="5.7" data-path="xargs.html">
<a href="./xargs.html">
<i class="fa fa-check"></i>
<b>5.7.</b>
xargs
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="6" data-path="arrays.html">
<a href="./arrays.html">
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<b>6.</b>
Arrays
</a>
</li>
<li class="chapter " data-level="7" data-path="metacharacters.html">
<a href="./metacharacters.html">
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<b>7.</b>
Shell Metacharacters
</a>
<ul class="articles">
<li class="chapter " data-level="7.1" data-path="precedence.html">
<a href="./precedence.html">
<i class="fa fa-check"></i>
<b>7.1.</b>
Precedence
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="8" data-path="expansions_and_substitutions.html">
<a href="./expansions_and_substitutions.html">
<i class="fa fa-check"></i>
<b>8.</b>
Expansions and Substitutions
</a>
<ul class="articles">
<li class="chapter " data-level="8.1" data-path="exp_and_sub/brace_expansion.html">
<a href="./exp_and_sub/brace_expansion.html">
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<b>8.1.</b>
Brace Expansion
</a>
</li>
<li class="chapter " data-level="8.2" data-path="exp_and_sub/tilde_expansion.html">
<a href="./exp_and_sub/tilde_expansion.html">
<i class="fa fa-check"></i>
<b>8.2.</b>
Tilde Expansion
</a>
</li>
<li class="chapter " data-level="8.3" data-path="exp_and_sub/parameter_expansion.html">
<a href="./exp_and_sub/parameter_expansion.html">
<i class="fa fa-check"></i>
<b>8.3.</b>
Parameter Expansion
</a>
</li>
<li class="chapter " data-level="8.4" data-path="exp_and_sub/arithmetic_expansion.html">
<a href="./exp_and_sub/arithmetic_expansion.html">
<i class="fa fa-check"></i>
<b>8.4.</b>
Arithmetic Expansion
</a>
</li>
<li class="chapter " data-level="8.5" data-path="exp_and_sub/command_substitution.html">
<a href="./exp_and_sub/command_substitution.html">
<i class="fa fa-check"></i>
<b>8.5.</b>
Command Substitution
</a>
</li>
<li class="chapter " data-level="8.6" data-path="exp_and_sub/process_substitution.html">
<a href="./exp_and_sub/process_substitution.html">
<i class="fa fa-check"></i>
<b>8.6.</b>
Process Substitution
</a>
</li>
<li class="chapter " data-level="8.7" data-path="exp_and_sub/word_splitting.html">
<a href="./exp_and_sub/word_splitting.html">
<i class="fa fa-check"></i>
<b>8.7.</b>
Word Splitting
</a>
</li>
<li class="chapter " data-level="8.8" data-path="exp_and_sub/filename_expansion.html">
<a href="./exp_and_sub/filename_expansion.html">
<i class="fa fa-check"></i>
<b>8.8.</b>
Filename Expansion
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="9" data-path="job_control.html">
<a href="./job_control.html">
<i class="fa fa-check"></i>
<b>9.</b>
Job Control
</a>
<ul class="articles">
<li class="chapter " data-level="9.1" data-path="session_and_process-group.html">
<a href="./session_and_process-group.html">
<i class="fa fa-check"></i>
<b>9.1.</b>
Session and Process Group
</a>
</li>
<li class="chapter " data-level="9.2" data-path="process_state_codes.html">
<a href="./process_state_codes.html">
<i class="fa fa-check"></i>
<b>9.2.</b>
Process State Codes
</a>
</li>
<li class="chapter " data-level="9.3" data-path="tty.html">
<a href="./tty.html">
<i class="fa fa-check"></i>
<b>9.3.</b>
TTY
</a>
</li>
<li class="chapter " data-level="9.4" data-path="mutual_exclusion.html">
<a href="./mutual_exclusion.html">
<i class="fa fa-check"></i>
<b>9.4.</b>
Mutual Exclusion
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="10" data-path="redirections.html">
<a href="./redirections.html">
<i class="fa fa-check"></i>
<b>10.</b>
Redirections
</a>
<ul class="articles">
<li class="chapter " data-level="10.1" data-path="file_descriptors.html">
<a href="./file_descriptors.html">
<i class="fa fa-check"></i>
<b>10.1.</b>
File Descriptors
</a>
</li>
<li class="chapter " data-level="10.2" data-path="here_document.html">
<a href="./here_document.html">
<i class="fa fa-check"></i>
<b>10.2.</b>
<< , <<<
</a>
</li>
<li class="chapter " data-level="10.3" data-path="pipe.html">
<a href="./pipe.html">
<i class="fa fa-check"></i>
<b>10.3.</b>
Pipe
</a>
</li>
<li class="chapter " data-level="10.4" data-path="named_pipe.html">
<a href="./named_pipe.html">
<i class="fa fa-check"></i>
<b>10.4.</b>
Named Pipe
</a>
</li>
<li class="chapter " data-level="10.5" data-path="buffering.html">
<a href="./buffering.html">
<i class="fa fa-check"></i>
<b>10.5.</b>
Buffering
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="11" data-path="signals_and_traps.html">
<a href="./signals_and_traps.html">
<i class="fa fa-check"></i>
<b>11.</b>
Signals and Traps
</a>
<ul class="articles">
<li class="chapter " data-level="11.1" data-path="kill.html">
<a href="./kill.html">
<i class="fa fa-check"></i>
<b>11.1.</b>
kill
</a>
</li>
<li class="chapter " data-level="11.2" data-path="trap.html">
<a href="./trap.html">
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<b>11.2.</b>
trap
</a>
</li>
<li class="chapter " data-level="11.3" data-path="signals_table.html">
<a href="./signals_table.html">
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<b>11.3.</b>
Signals Table
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="12" data-path="command_aliases.html">