子进程命令显示 FileNotFoundError: [Errno 2] No such file or directory

Question

我正在尝试通过在下面的代码中使用子进程模块来使用 python 运行 shell 命令，但我不知道为什么我的脚本会抛出如下错误。有人可以帮我解决我所缺少的吗？

Traceback (most recent call last):
  File "/Scripts/test_file.py", line 6, in <module>
    p2 = subprocess.Popen('sed s\'/&quot;/ /g\'', stdin=p1.stdout, stdout=subprocess.PIPE)
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/subprocess.py", line 854, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.8/lib/python3.8/subprocess.py", line 1702, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: "sed s'/&quot;/ /g'"`

---

import subprocess
#output3.txt='/Users/boggulv/Desktop/output3.txt'
p1 = subprocess.Popen( ['cat', 'output3.txt'], stdout=subprocess.PIPE)
print(p1)
p2 = subprocess.Popen('sed s\'/"/ /g\'', stdin=p1.stdout, stdout=subprocess.PIPE)
p3 = subprocess.Popen('grep "sO"', stdin=p2.stdout,stdout=subprocess.PIPE)
p4 = subprocess.Popen('grep -v "get"', stdin=p3.stdout, stdout=subprocess.PIPE)
p5 = subprocess.Popen('cut -d \',\' -f2', stdin=p4.stdout, stdout=subprocess.PIPE)
p6 = subprocess.Popen('sed \'s/"//g\'', stdin=p5.stdout, stdout=subprocess.PIPE)
p7 = subprocess.Popen('sort', stdin=p6.stdout, stdout=subprocess.PIPE)
p8 = subprocess.Popen('sort', stdin=p8.stdout, stdout=subprocess.PIPE)
p9 = subprocess.Popen('uniq -c', stdin=p8.stdout, stdout=subprocess.PIPE)
p0 = subprocess.Popen('sort -nr', stdin=p9.stdout, stdout=subprocess.PIPE)
print(p01.communicate())

现在尝试更改为列表。

p2 = subprocess.Popen('sed \'s/"/ /g\'', stdin=p1.stdout, stdout=subprocess.PIPE, shell=True)
p3 = subprocess.Popen(['grep','"shipOption"'], stdin=p2.stdout,stdout=subprocess.PIPE,shell = True)
p4 = subprocess.Popen(['grep','-v', '"getShipMethod"'], stdin=p3.stdout, stdout=subprocess.PIPE,shell = True)
p5 = subprocess.Popen(['cut','-d','\',\'', '-f2'], stdin=p4.stdout, stdout=subprocess.PIPE,shell = True)
p6 = subprocess.Popen(['sed','\'s/"//g\''],stdin=p5.stdout, stdout=subprocess.PIPE,shell = True)
p7 = subprocess.Popen(['sort'], stdin=p6.stdout, stdout=subprocess.PIPE,shell = True)
p8 = subprocess.Popen(['uniq', '-c'], stdin=p7.stdout, stdout=subprocess.PIPE,shell = True)
p9 = subprocess.Popen(['sort', '-nr'], stdin=p8.stdout, stdout=subprocess.PIPE,shell = True)
p0 = subprocess.Popen(['head', '-10'], stdin=p9.stdout, stdout=subprocess.PIPE,shell = True)```

New Error:

`usage: grep [-abcdDEFGHhIiJLlMmnOopqRSsUVvwXxZz] [-A num] [-B num] [-C[num]]
        [-e pattern] [-f file] [--binary-files=value] [--color=when]
        [--context[=num]] [--directories=action] [--label] [--line-buffered]
        [--null] [pattern] [file ...]
usage: grep [-abcdDEFGHhIiJLlMmnOopqRSsUVvwXxZz] [-A num] [-B num] [-C[num]]
        [-e pattern] [-f file] [--binary-files=value] [--color=when]
        [--context[=num]] [--directories=action] [--label] [--line-buffered]
        [--null] [pattern] [file ...]
usage: cut -b list [-n] [file ...]
       cut -c list [file ...]
       cut -f list [-s] [-w | -d delim] [file ...]
(b'', None)
cat: stdin: Input/output error`

Answer 1

你的命令还是错误的。如果您只想像 shell 那样运行这些命令，那么最简单的方法就是……使用 shell。

result = subprocess.run('''
# useless cat, but bear with
cat output3.txt |
sed 's/"/ /g' |
grep "shipOption" |
grep -v "getShipMethod" |
cut -d ',' -f2 |
sed 's/"//g' |
sort |
uniq -c |
sort -nr |
head -10
    ''',
    # Probably add these too
    check=True,
    capture_output=True,
    # We are using the shell for piping etc
    shell=True)

如果你想删除

shell=True

并手动运行所有这些进程，你必须了解 shell 的工作原理。特别是，您需要修复引号，以便您运行的命令的引号保留after shell 已处理语法引号。

p1 = subprocess.Popen(['cat', 'output3.txt'], stdout=subprocess.PIPE)  # still useless
p2 = subprocess.Popen(['sed','s/"/ /g'], stdin=p1.stdout, stdout=subprocess.PIPE)
p3 = subprocess.Popen(['grep', "shipOption"], stdin=p2.stdout,stdout=subprocess.PIPE)
p4 = subprocess.Popen(['grep', '-v', "getShipMethod"], stdin=p3.stdout, stdout=subprocess.PIPE)
p5 = subprocess.Popen(['cut', '-d', ',', '-f2'], stdin=p4.stdout, stdout=subprocess.PIPE)
p6 = subprocess.Popen(['sed', 's/"//g'],stdin=p5.stdout, stdout=subprocess.PIPE)
p7 = subprocess.Popen(['sort'], stdin=p6.stdout, stdout=subprocess.PIPE)
p8 = subprocess.Popen(['uniq', '-c'], stdin=p7.stdout, stdout=subprocess.PIPE)
p9 = subprocess.Popen(['sort', '-nr'], stdin=p8.stdout, stdout=subprocess.PIPE)
p0 = subprocess.Popen(['head', '-10'], stdin=p9.stdout, stdout=subprocess.PIPE)

请特别注意

sed

和

grep

的参数如何删除它们的外部引号，以及我们如何删除所有地方的

shell=True

。根据经验，如果

Popen

（或其他

subprocess

方法）的第一个参数是列表，则不应使用

shell=True

，反之亦然。 （在某些情况下，您可以将列表传递给

shell=True

，但是......我们甚至都不要开始去那里。）

尽管如此，所有这些似乎都没有实际意义，因为 Python 可以出色地完成所有这些事情。

from collections import Counter

counts = Counter()
with open('output3.txt', 'r', encoding='utf-8') as lines:
    for line in lines:
        line = line.rstrip('\n').replace('"', ' ')
        if "shipOption" in line and "getShipMethod" not in line:
            field = line.split(',')[1].replace('"', '')
            counts[field] += 1
print(counts.most_common(10))

可能您想将

rstrip

和

replace

放在

if

中以避免不必要的工作。当然，可以对 shell 管道进行相同的重构。

Answer 2

根据上面的 Gordon - 默认情况下 Popen() 处理

sed 's/"/ /g'

作为要运行的命令的名称，而不是命令名称加一个参数。因此，您需要执行以下操作之一：

p2 = subprocess.Popen(['sed', 's/"/ /g'], stdin=p1.stdout, stdout=subprocess.PIPE)

或

p2 = subprocess.Popen('sed \'s/"/ /g\'', stdin=p1.stdout, stdout=subprocess.PIPE, shell=True)

使用 shell=True 获取 Popen 函数将字符串拆分为包含命令和参数的列表。

另请注意，p0 是您的最后一个结果，但您调用了 p01.communicate()

Answer 3

假设您使用命令 'python hello.py --main' 以 --main 作为参数运行 hello.py 文件。

这将抛出一个错误，即没有找到这样的文件或目录。

subprocess.run(["python", "hello.py --main"],stdout=subprocess.PIPE)

在子流程中你会把它写成

subprocess.run(["python", "hello.py", "--main"],stdout=subprocess.PIPE)

你可以把它放在一个变量中并像这样打印从脚本返回的值

data = subprocess.run(["python", "hello.py", "--main"],stdout=subprocess.PIPE)

print(data.stdout.decode('utf-8').strip())