作者:狼与鹰的爱_340 | 来源:互联网 | 2023-02-04 17:20
1> Charles Duff..:
进程替换(<()
)是仅限bash的功能.因此,你需要一个shell,但它不能只是任何shell(就像在非Windows平台上/bin/sh
使用的那样shell=True
) - 它需要是bash.
subprocess.call(['bash', '-c', "comm -3 <(awk '{print $1}' File1.txt | sort | uniq) <(awk '{print $1}' File2.txt | sort | uniq) | grep -v '#' | sed 's/\t//g'"])
顺便说一下,如果您要使用任意文件名转到此路由,请将其传递到带外(如下所示:传递_
as $0
,File1.txt
as $1
和File2.txt
as $2
):
subprocess.call(['bash', '-c',
'''comm -3 <(awk '{print $1}' "$1" | sort | uniq) '''
''' <(awk '{print $1}' "$2" | sort | uniq) '''
''' | grep -v '#' | tr -d "\t"''',
'_', "File1.txt", "File2.txt"])
也就是说,最佳实践方法确实是自己建立链条.下面是用Python 3.6测试的(注意需要pass_fds
参数subprocess.Popen
来使文件描述符通过/dev/fd/##
可用的链接引用):
awk_filter='''! /#/ && !seen[$1]++ { print $1 }'''
p1 = subprocess.Popen(['awk', awk_filter],
stdin=open('File1.txt', 'r'),
stdout=subprocess.PIPE)
p2 = subprocess.Popen(['sort', '-u'],
stdin=p1.stdout,
stdout=subprocess.PIPE)
p3 = subprocess.Popen(['awk', awk_filter],
stdin=open('File2.txt', 'r'),
stdout=subprocess.PIPE)
p4 = subprocess.Popen(['sort', '-u'],
stdin=p3.stdout,
stdout=subprocess.PIPE)
p5 = subprocess.Popen(['comm', '-3',
('/dev/fd/%d' % (p2.stdout.fileno(),)),
('/dev/fd/%d' % (p4.stdout.fileno(),))],
pass_fds=(p2.stdout.fileno(), p4.stdout.fileno()),
stdout=subprocess.PIPE)
p6 = subprocess.Popen(['tr', '-d', '\t'],
stdin=p5.stdout,
stdout=subprocess.PIPE)
result = p6.communicate()
这是更多的代码,但(假设文件名在现实世界中被参数化)它也是更安全的代码 - 你不容易受到ShellShock这样的错误的攻击,这些错误是由启动shell的简单行为触发的,并且不是我需要担心在带外传递变量以避免注入攻击(除了在命令参数的上下文中 - 比如awk
脚本语言解释器本身).
也就是说,另一件要考虑的事情就是在原生Python中实现整个过程.
lines_1 = set(line.split()[0] for line in open('File1.txt', 'r') if not '#' in line)
lines_2 = set(line.split()[0] for line in open('File2.txt', 'r') if not '#' in line)
not_common = (lines_1 - lines_2) | (lines_2 - lines_1)
for line in sorted(not_common):
print line