command-line-arguments

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    <div class="example" id="command-line-arguments">
      <h2><a href="./">Go by Example</a>: Command-Line Arguments</h2>

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            <p><a href="http://en.wikipedia.org/wiki/Command-line_interface#Arguments"><em>Command-line arguments</em></a>
are a common way to parameterize execution of programs.
For example, <code>go run hello.go</code> uses <code>run</code> and
<code>hello.go</code> arguments to the <code>go</code> program.</p>

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            <div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
</pre></div>

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            <div class="highlight"><pre><span class="kn">import</span> <span class="s">&quot;os&quot;</span>
<span class="kn">import</span> <span class="s">&quot;fmt&quot;</span>
</pre></div>

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            <div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
</pre></div>

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            <p><code>os.Args</code> provides access to raw command-line
arguments. Note that the first value in this slice
is the path to the program, and <code>os.Args[1:]</code>
holds the arguments to the program.</p>

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            <div class="highlight"><pre>    <span class="nx">argsWithProg</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Args</span>
    <span class="nx">argsWithoutProg</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Args</span><span class="p">[</span><span class="mi">1</span><span class="p">:]</span>
</pre></div>

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            <p>You can get individual args with normal indexing.</p>

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            <div class="highlight"><pre>    <span class="nx">arg</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Args</span><span class="p">[</span><span class="mi">3</span><span class="p">]</span>
</pre></div>

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            <div class="highlight"><pre>    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">argsWithProg</span><span class="p">)</span>
    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">argsWithoutProg</span><span class="p">)</span>
    <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">arg</span><span class="p">)</span>
<span class="p">}</span>
</pre></div>

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            <p>To experiment with command-line arguments it&rsquo;s best to
build a binary with <code>go build</code> first.</p>

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            <div class="highlight"><pre><span class="gp">$</span> go build <span class="nb">command</span>-line-arguments.go
<span class="gp">$</span> ./command-line-arguments a b c d
<span class="go">[./command-line-arguments a b c d]       </span>
<span class="go">[a b c d]</span>
<span class="go">c</span>
</pre></div>

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            <p>Next we&rsquo;ll look at more advanced command-line processing
with flags.</p>

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        Next example: <a href="command-line-flags">Command-Line Flags</a>.
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