使用 Python 和 subprocces.call 执行脚本时出现问题,但在 Bash 中仍然有效
这是我第一次在这里寻求一些帮助,因为我更像是一个 ServerFault 人员。
我正在用 Python 编写一些脚本,到目前为止我一直很喜欢这门语言,但我遇到了一个小问题,它使我的脚本无法工作。
这是有问题的代码行:
subprocess.call('xen-create-image --hostname '+nom+' --memory '+memory+' --partitions=/root/scripts/part.tmp --ip '+ip+' --netmask '+netmask+' --gateway '+gateway+' --passwd',shell=True)
我用 os.popen 尝试过同样的事情。所有变量均已正确设置。
当我在常规 Linux shell 中执行相关命令时,它工作得很好,但是当我使用 Python 脚本执行它时,我会收到奇怪的错误。我什至用 print 函数替换了 subprocess.call() 以确保我使用的是命令的准确输出。
我查看了 shell 的环境变量,但它们几乎相同...我将发布我收到的错误,但我不确定它与我的问题相关。
在 /usr/share/perl5/Config/IniFiles.pm 第 614 行处使用未初始化值 $lines[0] 进行替换 (s///)。 在 /usr/share/perl5/Config/IniFiles.pm 第 628 行的模式匹配 (m//) 中使用未初始化值 $_。
我不是 Python 专家,所以我很可能在这里遗漏了一些东西。
预先感谢您的帮助,
Antoine
编辑
按照 miax 的建议,我停止使用 shell=True。相反,我查看了 subprocess 的 Python 文档,并使用了以下代码:
cmd = 'xen-create-image --hostname '+nom+' --memory '+memory+' --partitions=/root/scripts/part.tmp --ip '+ip+' --netmask '+netmask+' --gateway '+gateway+' --passwd'
args = shlex.split(cmd)
subprocess.call(args)
可悲的是,它没有改变任何东西...
EDIT2
我已经使用了 miax 给出的提示,但我仍然收到上述错误...这是我使用的代码。
cmd = ['xen-create-image', '--hostname', nom, '--memory', memory, '--partitions=/root/scripts/part.tmp', '--ip', ip, '--netmask', netmask, '--gateway', gateway, '--passwd']
subprocess.call(cmd)
这真的很奇怪...当我在常规 shell 中运行它时,确切的命令工作正常...
For the first time, I am asking a little bit of help over here as I am more of a ServerFault person.
I am doing some scripting in Python and I've been loving the language so far yet I have this little problem which is keeping my script from working.
Here is the code line in question :
subprocess.call('xen-create-image --hostname '+nom+' --memory '+memory+' --partitions=/root/scripts/part.tmp --ip '+ip+' --netmask '+netmask+' --gateway '+gateway+' --passwd',shell=True)
I have tried the same thing with os.popen. All the variables are correctly set.
When I execute the command in question in my regular Linux shell, it works perfectly fine but when I execute it using my Python scripts, I get bizarre errors. I even replaced subprocess.call() by the print function to make sure I am using the exact output of the command.
I went looking into environment variables of my shell but they are pretty much the same... I'll post the error I am getting but I'm not sure it's relevant to my problem.
Use of uninitialized value $lines[0] in substitution (s///) at /usr/share/perl5/Config/IniFiles.pm line 614.
Use of uninitialized value $_ in pattern match (m//) at /usr/share/perl5/Config/IniFiles.pm line 628.
I am not a Python expert so I'm most likely missing something here.
Thank you in advance for your help,
Antoine
EDIT
Following miax's advice, I stopped using shell=True. Instead I took a look at the Python documentation for subprocess and used the following piece of code :
cmd = 'xen-create-image --hostname '+nom+' --memory '+memory+' --partitions=/root/scripts/part.tmp --ip '+ip+' --netmask '+netmask+' --gateway '+gateway+' --passwd'
args = shlex.split(cmd)
subprocess.call(args)
Sadly, it doesn't change anything...
EDIT2
I have used the tip given by miax but I still get the above error... Here is the code that I have used.
cmd = ['xen-create-image', '--hostname', nom, '--memory', memory, '--partitions=/root/scripts/part.tmp', '--ip', ip, '--netmask', netmask, '--gateway', gateway, '--passwd']
subprocess.call(cmd)
This is really strange... The exact command works fine when I run it in the regular shell...
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您(在大多数情况下)不想将子进程与
shell=True
一起使用。将参数列表传递给命令。这
foo; rm -rf /; echo
作为一些值。$
或其他内容 - 它将由 shell 扩展并替换为该环境变量的内容。在不知道您的代码和 xen-create-image 的情况下,我认为这就是您的问题的原因。
PS:一定要检查命令的退出代码是否为零,如果不是零,请采取适当的措施。 (如果您确定它始终为零,请使用
check_call
,如果不为零,则会引发;这样,如果失败,您至少会有一个定义的行为。)You (in most cases) don't want to use subprocess with
shell=True
.Pass it a list of arguments to the command. That is
foo; rm -rf /; echo
as some of the values.$
or something – it will be expanded by the shell and replaced by the content of that environment variable.Without knowing your code and
xen-create-image
, I assume that is the cause of your problem.PS: Be sure to look if the exit code of the command is zero, and act appropriately if not. (If you are certain that it will always be zero, use
check_call
, which raises if it does not; that way you'll at least have a defined behavior if it fails.)xen-create-image
脚本是否以 hashbang 开头?也就是说,第一行是这样的吗?这是需要检查的一件事。另一个是您可以尝试将命令调用为:
您可能需要打印
cmd
来验证这是您打算运行的命令(即检查替换)。Does the
xen-create-image
script start with a hashbang? That is, is the first line something like? That is one thing to check. Another is that you can try to call your command as:
You might want to print
cmd
to verify this is the command you intend to run (i.e. check the substitutions).在失败的 Edit2 示例中,您认为为
xen-create-image
提供了以下选项:--hostname
--memory
--partitions=...
...但您实际上指定了以下选项:
--hostname
>空间--内存
空间--partitions= ...
你有这一行:
但你需要去掉多余的空格:
In your Edit2 example which is failing, you think you are giving the following options to
xen-create-image
:--hostname
--memory
--partitions=...
... but you are actually specifying the following options:
--hostname
space--memory
space--partitions=...
You have this line:
But you need to take out the extra spaces:
您需要
打印
您正在使用的命令:然后将该命令粘贴到您的 shell 中以确保它完全相同。
You need to
print
the command you are using:And then paste the command into your shell to make sure it is exactly the same.