[英]Python - Regex to Get directory name from HDFS
Im trying to extract a folder name from the result of a subprocess command. 我试图从子过程命令的结果中提取文件夹名称。 The result is Found 1 items
结果为找到1个项目
drwxr-xr-x - user user 0 2017-05-04 17:19 /user/oozie/share/lib/lib_20170406204755
I want to extract lib_20170406204755
. 我想提取
lib_20170406204755
。 I was able to do it using 我能够使用
process = subprocess.check_output(['hdfs','dfs','-ls','/user/oozie/share/lib'])
print process.split(' ')[-1].rstrip().split('/')[-1]
The folder is always lib_timestamp
该文件夹始终为
lib_timestamp
How can do this using regex? 如何使用正则表达式执行此操作?
No regex required here, you may as well use split()
: 这里不需要正则表达式,您也可以使用
split()
:
string = "drwxr-xr-x - user user 0 2017-05-04 17:19 /user/oozie/share/lib/lib_20170406204755"
folder = string.split('/')[-1]
print(folder)
# lib_20170406204755
But if you insist: 但是,如果您坚持:
[^/]+$
Python
:
Python
:
import re string = "drwxr-xr-x - user user 0 2017-05-04 17:19 /user/oozie/share/lib/lib_20170406204755" rx = re.compile(r'[^/]+$') folder = rx.search(string).group(0) print(folder) # lib_20170406204755
See a demo on regex101.com . 参见regex101.com上的演示 。
This should do the trick: 这应该可以解决问题:
(?!/)(lib_\\d*)
This regex is searching for for something that starts with lib_
followed by a bunch of numbers, should be enough if no similar folders are found on the result. 此正则表达式正在搜索以
lib_
开头且后跟一堆数字的内容,如果在结果上未找到类似的文件夹,则该内容就足够了。
(?!/)
is just to make sure that the folder is preceded by a /
(?!/)
只是为了确保该文件夹前面有一个/
A clean approach would be to use the os.path
module to pick apart paths. 一种干净的方法是使用
os.path
模块挑选路径。
import os
import subprocess
output = subprocess.check_output(['hdfs','dfs','-ls','/user/oozie/share/lib'])
# there are 8 columns in the output, i.e. we need a maximum of 7 splits per line
output_table = [line.split(maxsplit=7) for line in output.splitlines()]
# we are interested in the basename of that path
filenames = [os.path.basename(row[7]) for row in output_table]
with this test input: 使用此测试输入:
drwxr-xr-x - user user 0 2017-05-04 17:19 /user/oozie/share/lib/lib_20170406204755 drwxr-xr-x - user user 0 2017-05-04 17:19 /user/oozie/share/lib/lib_20110523212454
filenames will be ['lib_20170406204755', 'lib_20110523212454']
文件名将为
['lib_20170406204755', 'lib_20110523212454']
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