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<!--replace-end-7--><!--replace-end-4--><!--replace-end-1--></head><body><div class="ui fluid container universe"><!--replace-start-2--><!--replace-start-3--><!--replace-start-6--><div class="ui text container" id="zettel-container" style="position: relative"><div class="zettel-view"><article class="ui raised attached segment zettel-content"><div class="pandoc"><h1 id="title-h1">Functions in Bash</h1><p>We don’t name function parameters in the function declaration. Instead we have an implied index of arguments: <code>$1, $2, $3,...</code>. When the function is called, the first value after the function name becomes <code>$1</code> by default, then the subsequent arguments.</p><pre><code class="bash language-bash">function expandRange() {
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declare -a expandedRange=()
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for (( i=$1; i<=$2; i++ )); do
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expandedRange+=($i)
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done
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echo "${expandedRange[@]}"
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}</code></pre><pre><code class="bash language-bash">expandedRange=$(expandRange 1 4)
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echo $expandedRange
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# 1 2 3 4</code></pre><h2 id="get-all-arguments-as-an-array">Get all arguments as an array</h2><p>We can access all the arguments passed to a function using the <code>$@</code> syntax we encountered before when <span class="zettel-link-container errors"><span class="zettel-link" title="Wiki-link does not refer to any existing zettel"><a>Passing_arguments_to_Bash_scripts</a></span></span>. (Here a function is a kind of script in miniature so the process is the same.)</p><pre><code class="sh language-sh">function numberThings() {
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i=1
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for f in "$@"; do
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echo $i: "$f"
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(( i++ ))
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done
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}</code></pre><h2 id="local-variables">Local variables</h2><pre><code class="sh language-sh">var1="I'm variable 1"
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function myfunction() {
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var2="I'm variable 2"
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local var3="I'm variable 3"
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}
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myfunction
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echo $var1
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echo $var2
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echo $var3
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# I'm variable 1
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# I'm variable 2</code></pre><blockquote><p>The convention is to put functions at the top of the script, after the shebang and after the global variables</p></blockquote></div></article><nav class="ui attached segment deemphasized backlinksPane" id="neuron-backlinks-pane"><h3 class="ui header">Backlinks</h3><ul class="backlinks"><li><span class="zettel-link-container cf"><span class="zettel-link"><a href="Lists_and_arrays_in_Bash.html">Arrays in Bash</a></span></span><ul class="context-list" style="zoom: 85%;"><li class="item"><div class="pandoc"><p>When you pass an array as an argument to a <span class="zettel-link-container cf"><span class="zettel-link" title="Zettel: Functions in Bash"><a href="Functions_in_Bash.html">function</a></span></span> it will not immediately be understood to be an array.</p></div></li></ul></li></ul></nav><nav class="ui attached segment deemphasized bottomPane" id="neuron-tags-pane"><div><span class="ui basic label zettel-tag" title="Tag">shell</span></div></nav><nav class="ui bottom attached icon compact inverted menu blue" id="neuron-nav-bar"><!--replace-start-9--><!--replace-end-9--><a class="right item" href="impulse.html" title="Open Impulse"><i class="wave square icon"></i></a></nav></div></div><!--replace-end-6--><!--replace-end-3--><!--replace-end-2--><div class="ui center aligned container footer-version"><div class="ui tiny image"><a href="https://neuron.zettel.page"><img alt="logo" src="https://raw.githubusercontent.com/srid/neuron/master/assets/neuron.svg" title="Generated by Neuron 1.9.35.3" /></a></div></div></div></body></html> |