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After go1.16, go will use module mode by default, even when the repository is checked out under GOPATH or in a one-off directory. Add go.mod, go.sum to keep this repo buildable without opting out of the module mode. > go mod init github.com/mmcgrana/gobyexample > go mod tidy > go mod vendor In module mode, the 'vendor' directory is special and its contents will be actively maintained by the go command. pygments aren't the dependency the go will know about, so it will delete the contents from vendor directory. Move it to `third_party` directory now. And, vendor the blackfriday package. Note: the tutorial contents are not affected by the change in go1.16 because all the examples in this tutorial ask users to run the go command with the explicit list of files to be compiled (e.g. `go run hello-world.go` or `go build command-line-arguments.go`). When the source list is provided, the go command does not have to compute the build list and whether it's running in GOPATH mode or module mode becomes irrelevant.
196 lines
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196 lines
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: Signals</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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onkeydown = (e) => {
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if (e.key == "ArrowLeft") {
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window.location.href = 'execing-processes';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'exit';
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}
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}
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</script>
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<body>
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<div class="example" id="signals">
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<h2><a href="./">Go by Example</a>: Signals</h2>
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<table>
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<tr>
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<td class="docs">
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<p>Sometimes we’d like our Go programs to intelligently
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handle <a href="http://en.wikipedia.org/wiki/Unix_signal">Unix signals</a>.
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For example, we might want a server to gracefully
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shutdown when it receives a <code>SIGTERM</code>, or a command-line
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tool to stop processing input if it receives a <code>SIGINT</code>.
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Here’s how to handle signals in Go with channels.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/YRV64KEXJW1"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
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<span class="s">"fmt"</span>
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<span class="s">"os"</span>
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<span class="s">"os/signal"</span>
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<span class="s">"syscall"</span>
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<span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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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>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Go signal notification works by sending <code>os.Signal</code>
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values on a channel. We’ll create a channel to
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receive these notifications (we’ll also make one to
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notify us when the program can exit).</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">sigs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Signal</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
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<span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p><code>signal.Notify</code> registers the given channel to
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receive notifications of the specified signals.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="nx">signal</span><span class="p">.</span><span class="nx">Notify</span><span class="p">(</span><span class="nx">sigs</span><span class="p">,</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGINT</span><span class="p">,</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGTERM</span><span class="p">)</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>This goroutine executes a blocking receive for
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signals. When it gets one it’ll print it out
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and then notify the program that it can finish.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
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<span class="nx">sig</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">sigs</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sig</span><span class="p">)</span>
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<span class="nx">done</span> <span class="o"><-</span> <span class="kc">true</span>
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<span class="p">}()</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>The program will wait here until it gets the
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expected signal (as indicated by the goroutine
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above sending a value on <code>done</code>) and then exit.</p>
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</td>
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<td class="code">
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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="s">"awaiting signal"</span><span class="p">)</span>
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<span class="o"><-</span><span class="nx">done</span>
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<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"exiting"</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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<p>When we run this program it will block waiting for a
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signal. By typing <code>ctrl-C</code> (which the
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terminal shows as <code>^C</code>) we can send a <code>SIGINT</code> signal,
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causing the program to print <code>interrupt</code> and then exit.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="gp">$</span> go run signals.go
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<span class="go">awaiting signal</span>
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<span class="go">^C</span>
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<span class="go">interrupt</span>
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<span class="go">exiting</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="exit">Exit</a>.
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</p>
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<p class="footer">
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/signals">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"fmt\"\u000A \"os\"\u000A \"os/signal\"\u000A \"syscall\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' sigs :\u003D make(chan os.Signal, 1)\u000A done :\u003D make(chan bool, 1)\u000A');codeLines.push(' signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)\u000A');codeLines.push(' go func() {\u000A sig :\u003D \u003C-sigs\u000A fmt.Println()\u000A fmt.Println(sig)\u000A done \u003C- true\u000A }()\u000A');codeLines.push(' fmt.Println(\"awaiting signal\")\u000A \u003C-done\u000A fmt.Println(\"exiting\")\u000A}\u000A');codeLines.push('');
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</script>
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<script src="site.js" async></script>
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</body>
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</html>
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