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8.4 KiB
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197 lines
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<!DOCTYPE html>
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<html>
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<meta charset="utf-8">
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<title>Go в примерах: Переменные среды (Environment Variables)</title>
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<div class="example" id="environment-variables">
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<h2><a href="./">Go в примерах</a>: Переменные среды (Environment Variables)</h2>
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<table>
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<tr>
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<td class="docs">
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<p><a href="http://en.wikipedia.org/wiki/Environment_variable">Переменные среды (или переменные окружения)</a>
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- это <a href="http://www.12factor.net/config">универсальный механизм передачи информации о конфигурации
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в программы Unix</a>. Давайте
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посмотрим, как устанавливать, получать и перечислять переменные
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среды.</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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<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/--fC2aTdXEz" target="_blank"><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">"strings"</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>Чтобы установить пару ключ/значение, используйте
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<code>os.Setenv</code>. Чтобы получить значение для ключа,
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используйте <code>os.Getenv</code>. Это вернет пустую строку,
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если ключ не присутствует в среде.</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">os</span><span class="p">.</span><span class="nx">Setenv</span><span class="p">(</span><span class="s">"FOO"</span><span class="p">,</span> <span class="s">"1"</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="s">"FOO:"</span><span class="p">,</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Getenv</span><span class="p">(</span><span class="s">"FOO"</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="s">"BAR:"</span><span class="p">,</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Getenv</span><span class="p">(</span><span class="s">"BAR"</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>Используйте <code>os.Environ</code> для вывода списка всех пар
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ключ/значение в среде. Это возвращает спез строк в
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формате <code>KEY=value</code>. Вы можете использовать <code>strings.Split</code>,
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чтобы получить ключ и значение. Здесь мы печатаем
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все ключи.</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>
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<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Environ</span><span class="p">()</span> <span class="p">{</span>
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<span class="nx">pair</span> <span class="o">:=</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="nx">e</span><span class="p">,</span> <span class="s">"="</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">pair</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
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<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>Запуск программы показывает, что мы выбираем значение
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для <code>FOO</code>, которое мы установили в программе, но <code>BAR</code>
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пуст.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="gp">$</span> go run environment-variables.go
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<span class="go">FOO: 1</span>
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<span class="go">BAR: </span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Список ключей в среде будет зависеть от вашей системы.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="go">TERM_PROGRAM</span>
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<span class="go">PATH</span>
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<span class="go">SHELL</span>
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<span class="go">...</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>Если мы сначала установим <code>BAR</code> в среде, запущенная
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программа использует это значение.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="gp">$</span> <span class="nv">BAR</span><span class="o">=</span><span class="m">2</span> go run environment-variables.go
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<span class="go">FOO: 1</span>
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<span class="go">BAR: 2</span>
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<span class="go">...</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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Следующий пример: <a href="http-clients">HTTP клиенты (HTTP Clients)</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/environment-variables">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
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<br/>
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переведено Nick S. | <a href="https://github.com/badkaktus/gobyexample">исходники</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 \"strings\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' os.Setenv(\"FOO\", \"1\")\u000A fmt.Println(\"FOO:\", os.Getenv(\"FOO\"))\u000A fmt.Println(\"BAR:\", os.Getenv(\"BAR\"))\u000A');codeLines.push(' fmt.Println()\u000A for _, e := range os.Environ() {\u000A pair := strings.Split(e, \"=\")\u000A fmt.Println(pair[0])\u000A }\u000A}\u000A');codeLines.push('');codeLines.push('');codeLines.push('');
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</script>
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