简介
difflib作为python的标准库模块，无需安装，作用是比对文本之间的差异，且支持输出可读性比较强的HTML文档，与Linux下的diff命令相似。可以使用该模块比对代码和配置文件的差异，在版本控制方面非常有用。Python2.3以后的版本默认自带difflib模块，无需额外安装。
使用方法
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
import difflib
text1 = """text1:
This module provides classes and functions for comparing sequences.
including HTML and context and unified diffs.
difflib document v7.4
add string
"""
text1_lines = text1.splitlines()
text2 = """text2:
This module provides classes and functions for Comparing sequences.
including HTML and context and unified diffs.
difflib document v7.5"""
text2_lines = text2.splitlines()
d = difflib.Differ() #创建Differ对象
diff = d.compare(text1_lines,text2_lines) #采用compare方法对字符串进行比较
print "\n".join(list(diff)) #join将序列中的元素以指定的字符连接生成一个新的字符串str.join(sequence)
结果显示
- text1:
? ^
+ text2:
? ^
- This module provides classes and functions for comparing sequences.
? ^
+ This module provides classes and functions for Comparing sequences.
? ^
including HTML and context and unified diffs.
- difflib document v7.4
? ^
+ difflib document v7.5
? ^
- add string
|
各个差异符号表示含义
'-':包含在第一个序列行中，不包含在第二个序列行中
'+':包含在第二个序列行中，不包含在第一个序列行中
'':两个序列行一致
'?':标志两个序列行存在增量差异
'^':标志出两个序列存在的差异字符
采用HtmlDiff()的make_file()方法就可以生成美观的HTML文档，可以对上面的例子进行如下修改：
1 2 3 | d = difflib.Differ()
diff = d.compare(text1_lines,text2_lines)
print "\n".join(list(diff))
|
将以上修改为
1 2 3 | d = difflib.HtmlDiff()
diff = d.make_file(text1_lines,text2_lines)
print diff
|
将以上程序保存为sample2.py ,运行python sample2.py > diff.html，用浏览器打开保存的html文件
当我们维护多个Nginx配置时，时长会比对不同版本配置文件的差异，使运维人员更加清晰地了解不同版本迭代后的更新项，实现的思路是读取两个需对比的配置文件，再以换行符作为分隔符，调用difflib.HtmlDiff()生成HTML格式的差异文档。具体实现如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | #!/usr/bin/env python
# -*- coding: utf-8 -*-
import difflib
import sys
try:
textfile1 = sys.argv[1]
textfile2 = sys.argv[2]
except Exception,e:
print "Error:" +str(e)
print "Usage: python sample3.py filename1 filename2"
sys.exit()
def readfile(filename):
try:
filehandle = open(filename,'rb')
text = filehandle.read().splitlines()
filehandle.close()
return text
except IOError as error:
print ('Read file Error:' +str(error))
sys.exit()
text1_lines = readfile(textfile1)
text2_lines = readfile(textfile2)
d = difflib.HtmlDiff()
print d.make_file(text1_lines,text2_lines)
|
运行代码 ython sample3.py nginx.conf.v1 nginx.conf.v2 > sample3_diff.html
通过浏览器查看两个文件差异
附nginx配置文件
nginx.conf.zip
|
