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最近有一个小需求:在一个目录下有很多文件,每个文件的第一行是BEGIN开头的,最后一行是END开头的,中间每一行有多列,数量不等,第一列称为"DN", 第二列称为"CV",DN和CV的联合作为主键,现在需要检测文件中是否有重复的DN-CV。
于是写了个简单的python程序
#! /usr/bin/python import os import sys cmd = "cat /home/zhangj/hosts/* | grep -v BEGIN | grep -v END" def check_dc_line(): has_duplicate = False dc_set = set() for dc_line in os.popen(cmd, 'r').readlines(): dc_token = dc_line.split() dn = dc_token[0] cv = dc_token[1] dc = dn + "," + cv if dc in dc_set: print "duplicate dc found:", dc has_duplicate = True else: dc_set.add(dc) return has_duplicate if not check_dc_line(): print "no duplicate dc"
对于250个文件,共60万行的数据,过滤一遍约1.67秒
有点不甘心这个效率,于是又写了一个同样功能的shell脚本
#! /bin/bash cat /home/zhangj/hosts/* | grep -v BEGIN | grep -v END | awk ' BEGIN { has_duplicate = 0 } { dc = $1","$2; if (dc in dc_set) { print "duplicate dc found", dc has_duplicate = 1 } else { dc_set[dc] = 1 } } END { if (has_duplicate ==0) { print "no duplicate dc found" } } '
为了进一步比较,重复了10次实验。
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