带有shell = True的Python子进程不允许进行进程替换吗? [英] Process substitution not allowed by Python's subprocess with shell=True?
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问题描述
这是一个过程替换的玩具示例,在Bash中效果很好:
Here is a toy example of process substitution that works fine in Bash:
$ wc -l <(pwd)
1 /proc/self/fd/11
那么,当从shell的shell = True的Python子进程中调用该命令时,为什么同一命令会给出语法错误?
So why does the same command give a syntax error when invoked from Python's subprocess with shell=True?
>>> subprocess.check_call('wc -l <(pwd)', shell=True)
/bin/sh: 1: Syntax error: "(" unexpected
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/path/to/my/python/lib/python3.5/subprocess.py", line 581, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command 'wc -l <(pwd)' returned non-zero exit status 2
推荐答案
/bin/sh:1:语法错误:("意外
/bin/sh: 1: Syntax error: "(" unexpected
您有 bashism .根据POSIX无效,这是/bin/sh
实现的.
You have a bashism. It is not valid according to POSIX, which is what /bin/sh
implements.
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