python – 使用shell时返回subprocess.call()参数= True w / lis

参见英文答案 > subprocess.call using string vs using list????????????????????????????????????1个
我试图让python的subprocess.call方法通过列表(由一系列字符串组成)接受一些args命令,如python文档中所建议的那样.为了在将它放入我的实际脚本之前探索这种行为,我打开了IPython,运行了一些涉及shell设置和args命令的不同组合的命令,并得到以下行为：

In [3]: subprocess.call(['ls','-%sl' %'a'])
total 320
drwxr-xr-x  20 Kohaugustine  staff   680 Oct 15 16:55 .
drwxr-xr-x   5 Kohaugustine  staff   170 Sep 12 17:16 ..
-rwxr-xr-x   1 Kohaugustine  staff  8544 Oct 15 16:55 a.out
-rwxr-xr-x   1 Kohaugustine  staff  8544 Oct  3 10:28 ex1-6
-rw-r--r--@  1 Kohaugustine  staff   204 Oct  3 10:28 ex1-6.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Oct  3 10:15 ex1-7
-rw-r--r--@  1 Kohaugustine  staff    71 Oct  3 10:15 ex1-7.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:22 hello
-rw-r--r--@  1 Kohaugustine  staff    58 Sep 12 16:27 hello.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:24 hello.o
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:24 hello_1.o
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:27 hello_2.o
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:27 hello_3.o
-rwxr-xr-x   1 Kohaugustine  staff  8544 Oct 15 16:55 lesson_1-5
-rw-r--r--@  1 Kohaugustine  staff   185 Sep 28 10:35 lesson_1-5.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 21 10:06 temperature.o
-rw-r--r--@  1 Kohaugustine  staff   406 Sep 21 09:54 temperature_ex1-3.c
-rw-r--r--@  1 Kohaugustine  staff   582 Sep 21 10:06 temperature_ex1-4.c
-rw-r--r--@  1 Kohaugustine  staff   178 Sep 23 17:21 temperature_ex1-5.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 23 17:21 temperature_ex1-5.o
Out[3]: 0

In [4]: subprocess.call(['ls','-%sl' %'a'],shell=True)
a.out           ex1-7           hello.c         hello_2.o       lesson_1-5.c            temperature_ex1-4.c
ex1-6           ex1-7.c         hello.o         hello_3.o       temperature.o           temperature_ex1-5.c
ex1-6.c         hello           hello_1.o       lesson_1-5      temperature_ex1-3.c     temperature_ex1-5.o
Out[4]: 0

In [6]: subprocess.call(['ls','-al'])    
total 320
drwxr-xr-x  20 Kohaugustine  staff   680 Oct 15 16:55 .
drwxr-xr-x   5 Kohaugustine  staff   170 Sep 12 17:16 ..
-rwxr-xr-x   1 Kohaugustine  staff  8544 Oct 15 16:55 a.out
-rwxr-xr-x   1 Kohaugustine  staff  8544 Oct  3 10:28 ex1-6
-rw-r--r--@  1 Kohaugustine  staff   204 Oct  3 10:28 ex1-6.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Oct  3 10:15 ex1-7
-rw-r--r--@  1 Kohaugustine  staff    71 Oct  3 10:15 ex1-7.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:22 hello
-rw-r--r--@  1 Kohaugustine  staff    58 Sep 12 16:27 hello.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:24 hello.o
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:24 hello_1.o
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:27 hello_2.o
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 12 16:27 hello_3.o
-rwxr-xr-x   1 Kohaugustine  staff  8544 Oct 15 16:55 lesson_1-5
-rw-r--r--@  1 Kohaugustine  staff   185 Sep 28 10:35 lesson_1-5.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 21 10:06 temperature.o
-rw-r--r--@  1 Kohaugustine  staff   406 Sep 21 09:54 temperature_ex1-3.c
-rw-r--r--@  1 Kohaugustine  staff   582 Sep 21 10:06 temperature_ex1-4.c
-rw-r--r--@  1 Kohaugustine  staff   178 Sep 23 17:21 temperature_ex1-5.c
-rwxr-xr-x   1 Kohaugustine  staff  8496 Sep 23 17:21 temperature_ex1-5.o
Out[6]: 0

In [7]: subprocess.call(['ls','-al'],shell = True)
a.out           ex1-7           hello.c         hello_2.o       lesson_1-5.c            temperature_ex1-4.c
ex1-6           ex1-7.c         hello.o         hello_3.o       temperature.o           temperature_ex1-5.c
ex1-6.c         hello           hello_1.o       lesson_1-5      temperature_ex1-3.c     temperature_ex1-5.o
Out[7]: 0

似乎每当shell = True时,输出似乎与：

In [9]: subprocess.call(['ls'])
a.out           ex1-7           hello.c         hello_2.o       lesson_1-5.c            temperature_ex1-4.c
ex1-6           ex1-7.c         hello.o         hello_3.o       temperature.o           temperature_ex1-5.c
ex1-6.c         hello           hello_1.o       lesson_1-5      temperature_ex1-3.c     temperature_ex1-5.o
Out[9]: 0

我很困惑;当我设置shell = True时,’-a’选项会发生什么？ shell没有读过吗？我已经阅读了文档,并且它说当shell = True时,这意味着我的指定命令将通过shell执行,因此它应该意味着ls -a被送到shell并由shell执行.那么为什么[4]和[7]中的行为呢？
pydocs也没有直接解释它(虽然它确实说明当我们设置shell = False时子进程不会做什么);当我们让shell = False时它意味着什么？是否在操作系统中生成了一个新进程而没有shell实际控制它？

另外,如果我在[3]和[4]中使用格式字符串看起来真的很尴尬,那因为在我的实际脚本中我将使用subprocess.call,我将不得不依赖这些格式要在相应的命令选项中替换的字符串.我无法硬编码某些命令行选项.对于args使用纯字符串也是不可能的,因为在我的脚本中将有一个方法必须对命令执行列表操作.我不知道是否有更好的方法可以解决这个问题,所以如果有人能提出不同的建议,那么真的会有所帮助.

非常感谢你！

["/bin/sh","-c","ls","-al"]

# Produces ["/bin/sh","ls -al"]
subprocess.call("ls -al",shell=True)