blocks|key|993686|text|通过shell执行程序意味着根据所调用的shell的语法和语义规则解释传递给程序的所有用户输入。充其量，这只会给用户带来不便，因为用户必须遵守这些规则。例如，包含特殊shell字符(如引号或空格)的路径必须转义。在最坏的情况下，它会导致安全泄漏，因为用户可以执行任意程序。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|993687|shell=True有时可以方便地使用特定的shell特性，如拆分单词或扩展参数。但是，如果需要这样的功能，请使用提供给您的其他模块(例如，用于参数扩展的os.path.expandvars()或用于分词的shlex+)。这意味着更多的工作，但避免了其他问题。|offset|length|style|CODE|993688|简而言之:一定要避免使用shell=True。|993689|entityMap^0|0|0|A|25|K|2V|5|0|C|A|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]|$D|P|E|Q|F|G]|$D|R|E|S|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|T|8|@$D|U|E|V|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|K|$]]

Executing programs through the shell means that all user input passed to the program is interpreted according to the syntax and semantic rules of the invoked shell. At best, this only causes inconvenience to the user, because the user has to obey these rules. For instance, paths containing special shell characters like quotation marks or blanks must be escaped. At worst, it causes security leaks, because the user can execute arbitrary programs.

<code>shell=True</code> is sometimes convenient to make use of specific shell features like word splitting or parameter expansion. However, if such a feature is required, make use of other modules are given to you (e.g. <code>os.path.expandvars()</code> for parameter expansion or <code>shlex</code> for word splitting). This means more work, but avoids other problems.

In short: Avoid <code>shell=True</code> by all means.

blocks|key|993714|text|这里显示了一个Shell=True可能出错的示例|type|unstyled|depth|inlineStyleRanges|entityRanges|data|993715|>>>+from+subprocess+import+call
>>>+filename+=+input("What+file+would+you+like+to+display?\n")
What+file+would+you+like+to+display?
non_existent;+rm+-rf+/+#+THIS+WILL+DELETE+EVERYTHING+IN+ROOT+PARTITION!!!
>>>+call("cat+"+%2B+filename,+shell=True)+#+Uh-oh.+This+will+end+badly...|code-block|syntax|javascript|993716|请在此处查看文档：subprocess.call()|offset|length|993717|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.python.org/2/library/subprocess.html#frequently-used-arguments^0|0|0|9|H|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

An example where things could go wrong with Shell=True is shown here

<pre><code>&gt;&gt;&gt; from subprocess import call
&gt;&gt;&gt; filename = input("What file would you like to display?\n")
What file would you like to display?
non_existent; rm -rf / # THIS WILL DELETE EVERYTHING IN ROOT PARTITION!!!
&gt;&gt;&gt; call("cat " + filename, shell=True) # Uh-oh. This will end badly...
</code></pre>

Check the doc here: <a href="https://docs.python.org/2/library/subprocess.html#frequently-used-arguments">subprocess.call()</a>

blocks|key|993754|text|假设您正在使用shell=False，并以列表的形式提供命令。一些恶意用户试图插入“rm”命令。您将看到，'rm‘将被解释为参数，实际上'ls’将尝试查找名为'rm‘的文件|type|unstyled|depth|inlineStyleRanges|entityRanges|data|993755|>>>+subprocess.run(['ls','-ld','/home','rm','/etc/passwd'])
ls:+rm:+No+such+file+or+directory
-rw-r--r--++++1+root+++++root++++++++++1172+May+28++2020+/etc/passwd
drwxr-xr-x++++2+root+++++root++++++++++4096+May+29++2020+/home
CompletedProcess(args=['ls',+'-ld',+'/home',+'rm',+'/etc/passwd'],+returncode=1)|code-block|syntax|javascript|993756|默认情况下，如果您没有正确控制输入，shell=False就不是安全的。您仍然可以执行危险的命令。|993757|>>>+subprocess.run(['rm','-rf','/home'])
CompletedProcess(args=['rm',+'-rf',+'/home'],+returncode=0)
>>>+subprocess.run(['ls','-ld','/home'])
ls:+/home:+No+such+file+or+directory
CompletedProcess(args=['ls',+'-ld',+'/home'],+returncode=1)
>>>|993758|我的大多数应用程序都是在容器环境中编写的，我知道要调用的是哪个shell，并且我不会接受任何用户输入。|993759|所以在我的用例中，我看不到任何安全风险。而且创建长的命令字符串要容易得多。希望我没记错。|993760|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|V|8|@]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

let's assume you are using shell=False and providing the command as a list. And some malicious user tried injecting an 'rm' command.
You will see, that 'rm' will be interpreted as an argument and effectively 'ls' will try to find a file called 'rm'
<pre><code>&gt;&gt;&gt; subprocess.run(['ls','-ld','/home','rm','/etc/passwd'])
ls: rm: No such file or directory
-rw-r--r-- 1 root root 1172 May 28 2020 /etc/passwd
drwxr-xr-x 2 root root 4096 May 29 2020 /home
CompletedProcess(args=['ls', '-ld', '/home', 'rm', '/etc/passwd'], returncode=1)
</code></pre>
shell=False is not a secure by default, if you don't control the input properly. You can still execute dangerous commands.
<pre><code>&gt;&gt;&gt; subprocess.run(['rm','-rf','/home'])
CompletedProcess(args=['rm', '-rf', '/home'], returncode=0)
&gt;&gt;&gt; subprocess.run(['ls','-ld','/home'])
ls: /home: No such file or directory
CompletedProcess(args=['ls', '-ld', '/home'], returncode=1)
&gt;&gt;&gt;
</code></pre>
I am writing most of my applications in container environments, I know which shell is being invoked and i am not taking any user input.
So in my use case, I see no security risk. And it is much easier creating long string of commands. Hope I am not wrong.

I am calling different processes with the <code>subprocess</code> module. However, I have a question.

In the following codes:

<pre><code>callProcess = subprocess.Popen(['ls', '-l'], shell=True)
</code></pre>

and 

<pre><code>callProcess = subprocess.Popen(['ls', '-l']) # without shell
</code></pre>

Both work. After reading the docs, I came to know that <code>shell=True</code> means executing the code through the shell. So that means in absence, the process is directly started. 

So what should I prefer for my case - I need to run a process and get its output. What benefit do I have from calling it from within the shell or outside of it.

Actual meaning of 'shell=True' in subprocess

容器

我使用subprocess模块调用不同的进程。然而，我有一个问题。在以下代码中：callProcess = subprocess.Popen(['ls', '-l'], shell=True)和callProcess = subprocess.Popen(['ls', '-l']) # without shell这两种...

问子流程中'shell=True‘的实际含义
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