forked from gobyexample-cn/gobyexample-cn.github.io
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathexecing-processes.html
197 lines (152 loc) · 7.95 KB
/
execing-processes.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 执行进程</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'spawning-processes';
}
if (e.key == "ArrowRight") {
window.location.href = 'signals';
}
}
</script>
<body>
<div class="example" id="execing-processes">
<h2><a href="./">Go by Example 中文版</a>: 执行进程</h2>
<table>
<tr>
<td class="docs">
<p>在前面的例子中，我们了解了<a href="spawning-processes">生成外部进程</a>的知识，
当我们需要在运行的 Go 流程中访问的外部流程时，便可以执行此操作。
但是有时候，我们只想用其它（也许是非 Go）的进程，来完全替代当前的 Go 进程。
这时，我们可以使用经典的 <a href="http://en.wikipedia.org/wiki/Exec_(operating_system)"><code>exec</code></a> 函数的 Go 的实现。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/_nmhf7Ap8xD"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="p">(</span>
<span class="s">"os"</span>
<span class="s">"os/exec"</span>
<span class="s">"syscall"</span>
<span class="p">)</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kd">func</span> <span class="nf">main</span><span class="p">()</span> <span class="p">{</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>在这个例子中，我们将执行 <code>ls</code> 命令。
Go 要求我们提供想要执行的可执行文件的绝对路径，
所以我们将使用 <code>exec.LookPath</code> 找到它（应该是 <code>/bin/ls</code>）。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">binary</span><span class="p">,</span> <span class="nx">lookErr</span> <span class="o">:=</span> <span class="nx">exec</span><span class="p">.</span><span class="nf">LookPath</span><span class="p">(</span><span class="s">"ls"</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">lookErr</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="nb">panic</span><span class="p">(</span><span class="nx">lookErr</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>Exec</code> 需要的参数是切片的形式的（不是放在一起的一个大字符串）。
我们给 <code>ls</code> 一些基本的参数。注意，第一个参数需要是程序名。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">args</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"ls"</span><span class="p">,</span> <span class="s">"-a"</span><span class="p">,</span> <span class="s">"-l"</span><span class="p">,</span> <span class="s">"-h"</span><span class="p">}</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>Exec</code> 同样需要使用<a href="environment-variables">环境变量</a>。
这里我们仅提供当前的环境变量。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="nx">env</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nf">Environ</span><span class="p">()</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p>这里是真正的 <code>syscall.Exec</code> 调用。
如果这个调用成功，那么我们的进程将在这里结束，并被 <code>/bin/ls -a -l -h</code> 进程代替。
如果存在错误，那么我们将会得到一个返回值。</p>
</td>
<td class="code">
<pre class="chroma">
<span class="nx">execErr</span> <span class="o">:=</span> <span class="nx">syscall</span><span class="p">.</span><span class="nf">Exec</span><span class="p">(</span><span class="nx">binary</span><span class="p">,</span> <span class="nx">args</span><span class="p">,</span> <span class="nx">env</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">execErr</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="nb">panic</span><span class="p">(</span><span class="nx">execErr</span><span class="p">)</span>
<span class="p">}</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
<p>当我们运行程序时，它会替换为 <code>ls</code>。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="gp">$</span> go run execing-processes.go
<span class="go">total 16
</span><span class="go">drwxr-xr-x 4 mark 136B Oct 3 16:29 .
</span><span class="go">drwxr-xr-x 91 mark 3.0K Oct 3 12:50 ..
</span><span class="go">-rw-r--r-- 1 mark 1.3K Oct 3 16:28 execing-processes.go</span></pre>
</td>
</tr>
<tr>
<td class="docs">
<p>注意 Go 没有提供 Unix 经典的 <code>fork</code> 函数。
一般来说，这没有问题，因为启动协程、生成进程和执行进程，
已经涵盖了 fork 的大多数使用场景。</p>
</td>
<td class="code empty">
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="signals.html">信号</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
</div>
<script>
var codeLines = [];
codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import (\u000A \"os\"\u000A \"os/exec\"\u000A \"syscall\"\u000A)\u000A');codeLines.push('func main() {\u000A');codeLines.push(' binary, lookErr :\u003D exec.LookPath(\"ls\")\u000A if lookErr !\u003D nil {\u000A panic(lookErr)\u000A }\u000A');codeLines.push(' args :\u003D []string{\"ls\", \"-a\", \"-l\", \"-h\"}\u000A');codeLines.push(' env :\u003D os.Environ()\u000A');codeLines.push(' execErr :\u003D syscall.Exec(binary, args, env)\u000A if execErr !\u003D nil {\u000A panic(execErr)\u000A }\u000A}\u000A');codeLines.push('');codeLines.push('');
</script>
<script src="site.js" async></script>
</body>
</html>