77 lines
12 KiB
HTML
77 lines
12 KiB
HTML
|
<!DOCTYPE html><html><head><meta content="text/html; charset=utf-8" http-equiv="Content-Type" /><meta content="width=device-width, initial-scale=1" name="viewport" /><!--replace-start-0--><!--replace-start-5--><!--replace-start-8--><title>Functions in Bash - My Zettelkasten</title><!--replace-end-8--><!--replace-end-5--><!--replace-end-0--><link href="https://cdn.jsdelivr.net/npm/fomantic-ui@2.8.7/dist/semantic.min.css" rel="stylesheet" /><link href="https://fonts.googleapis.com/css?family=Merriweather|Libre+Franklin|Roboto+Mono&display=swap" rel="stylesheet" /><!--replace-start-1--><!--replace-start-4--><!--replace-start-7--><link href="https://raw.githubusercontent.com/srid/neuron/master/assets/neuron.svg" rel="icon" /><meta content="We don’t name function parameters in the function declaration. Instead we have an implied index of arguments: $1, $2, $3,.... When the function is called, the first value after the function name becomes $1 by default, then the subsequent arguments." name="description" /><meta content="Functions in Bash" property="og:title" /><meta content="My Zettelkasten" property="og:site_name" /><meta content="article" property="og:type" /><meta content="Functions_in_Bash" property="neuron:zettel-id" /><meta content="Functions_in_Bash" property="neuron:zettel-slug" /><meta content="shell" property="neuron:zettel-tag" /><script type="application/ld+json">[]</script><style type="text/css">body{background-color:#eeeeee !important;font-family:"Libre Franklin", serif !important}body .ui.container{font-family:"Libre Franklin", serif !important}body h1, h2, h3, h4, h5, h6, .ui.header, .headerFont{font-family:"Merriweather", sans-serif !important}body code, pre, tt, .monoFont{font-family:"Roboto Mono","SFMono-Regular","Menlo","Monaco","Consolas","Liberation Mono","Courier New", monospace !important}body div.z-index p.info{color:#808080}body div.z-index ul{list-style-type:square;padding-left:1.5em}body div.z-index .uplinks{margin-left:0.29999em}body .zettel-content h1#title-h1{background-color:rgba(33,133,208,0.1)}body nav.bottomPane{background-color:rgba(33,133,208,2.0e-2)}body div#footnotes{border-top-color:#2185d0}body p{line-height:150%}body img{max-width:100%}body .deemphasized{font-size:0.94999em}body .deemphasized:hover{opacity:1}body .deemphasized:not(:hover){opacity:0.69999}body .deemphasized:not(:hover) a{color:#808080 !important}body div.container.universe{padding-top:1em}body div.zettel-view ul{padding-left:1.5em;list-style-type:square}body div.zettel-view .pandoc .highlight{background-color:#ffff00}body div.zettel-view .pandoc .ui.disabled.fitted.checkbox{margin-right:0.29999em;vertical-align:middle}body div.zettel-view .zettel-content .metadata{margin-top:1em}body div.zettel-view .zettel-content .metadata div.date{text-align:center;color:#808080}body div.zettel-view .zettel-content h1{padding-top:0.2em;padding-bottom:0.2em;text-align:center}body div.zettel-view .zettel-content h2{border-bottom:solid 1px #4682b4;margin-bottom:0.5em}body div.zettel-view .zettel-content h3{margin:0px 0px 0.4em 0px}body div.zettel-view .zettel-content h4{opacity:0.8}body div.zettel-view .zettel-content div#footnotes{margin-top:4em;border-top-style:groove;border-top-width:2px;font-size:0.9em}body div.zettel-view .zettel-content div#footnotes ol > li > p:only-of-type{display:inline;margin-right:0.5em}body div.zettel-view .zettel-content aside.footnote-inline{width:30%;padding-left:15px;margin-left:15px;float:right;background-color:#d3d3d3}body div.zettel-view .zettel-content .overflows{overflow:auto}body div.zettel-view .zettel-content code{margin:auto auto auto auto;font-size:100%}body div.zettel-view .zettel-content p code, li code, ol code{padding:0.2em 0.2em 0.2em 0.2em;background-color:#f5f2f0}body div.zettel-view .zettel-content pre{overflow:auto}body div.zettel-view .zettel-content dl dt{font-weight:bold}body div.zettel-view .zettel-content blockquote{background-color:#f9f9f9;border-left:solid 10px #cccccc;margin:1.5em 0px 1.5em 0px;padding:0.5em 10px 0.5em 10px}body div.zettel-view .zettel-content.raw{back
|
|||
|
|
async=""
|
|||
|
|
id="MathJax-script"
|
|||
|
|
src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"
|
|||
|
|
></script>
|
|||
|
|
<link
|
|||
|
|
href="https://cdnjs.cloudflare.com/ajax/libs/prism/1.23.0/themes/prism.min.css"
|
|||
|
|
rel="stylesheet"
|
|||
|
|
/><link rel="preconnect" href="https://fonts.googleapis.com" /><link
|
|||
|
|
rel="preconnect"
|
|||
|
|
href="https://fonts.gstatic.com"
|
|||
|
|
crossorigin
|
|||
|
|
/><link
|
|||
|
|
href="https://fonts.googleapis.com/css2?family=IBM+Plex+Mono:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;1,100;1,200;1,300;1,400;1,500;1,600;1,700&family=IBM+Plex+Sans+Condensed:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;1,100;1,200;1,300;1,400;1,500;1,600;1,700&family=IBM+Plex+Sans:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;1,100;1,200;1,300;1,400;1,500;1,600;1,700&family=IBM+Plex+Serif:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;1,100;1,200;1,300;1,400;1,500;1,600;1,700&display=swap"
|
|||
|
|
rel="stylesheet"
|
|||
|
|
/>
|
|||
|
|
<script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.23.0/components/prism-core.min.js"></script>
|
|||
|
|
<script src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.23.0/plugins/autoloader/prism-autoloader.min.js"></script>
|
|||
|
|
<style>
|
|||
|
|
body .ui.container,
|
|||
|
|
body ul {
|
|||
|
|
font-family: "IBM Plex Sans" !important;
|
|||
|
|
}
|
|||
|
|
body blockquote {
|
|||
|
|
border-left-width: 3px !important;
|
|||
|
|
font-style: italic;
|
|||
|
|
}
|
|||
|
|
.headerFont,
|
|||
|
|
.ui.header,
|
|||
|
|
body h1,
|
|||
|
|
h2,
|
|||
|
|
h3,
|
|||
|
|
h4,
|
|||
|
|
h5,
|
|||
|
|
h6 {
|
|||
|
|
font-family: "IBM Plex Sans Condensed" !important;
|
|||
|
|
}
|
|||
|
|
body p {
|
|||
|
|
line-height: 1.4;
|
|||
|
|
}
|
|||
|
|
.monoFont,
|
|||
|
|
body code,
|
|||
|
|
pre,
|
|||
|
|
tt {
|
|||
|
|
font-family: "IBM Plex Mono" !important;
|
|||
|
|
font-size: 12px !important;
|
|||
|
|
line-height: 1.4 !important;
|
|||
|
|
}
|
|||
|
|
</style>
|
|||
|
|
<!--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() {
|
|||
|
|
declare -a expandedRange=()
|
|||
|
|
for (( i=$1; i<=$2; i++ )); do
|
|||
|
|
expandedRange+=($i)
|
|||
|
|
done
|
|||
|
|
echo "${expandedRange[@]}"
|
|||
|
|
}</code></pre><pre><code class="bash language-bash">expandedRange=$(expandRange 1 4)
|
|||
|
|
echo $expandedRange
|
|||
|
|
# 1 2 3 4</code></pre><h2 id="get-all-arguments-as-an-array">Get all arguments as an array</h2><p>We can access all the arguments passed to a function using the <code>$@</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() {
|
|||
|
|
i=1
|
|||
|
|
for f in "$@"; do
|
|||
|
|
echo $i: "$f"
|
|||
|
|
(( i++ ))
|
|||
|
|
done
|
|||
|
|
}</code></pre><h2 id="local-variables">Local variables</h2><pre><code class="sh language-sh">var1="I'm variable 1"
|
|||
|
|
|
|||
|
|
function myfunction() {
|
|||
|
|
var2="I'm variable 2"
|
|||
|
|
local var3="I'm variable 3"
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
myfunction
|
|||
|
|
echo $var1
|
|||
|
|
echo $var2
|
|||
|
|
echo $var3
|
|||
|
|
|
|||
|
|
# I'm variable 1
|
|||
|
|
# 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>
|