【原创】python修改文件某行的内容

 1 # -*-coding:utf-8 -*-
 2
 3
 4 # @version: 1.0
 5 # @author: Zhipeng Zhang
 6 # @date: '2015/5/28'
 7 import os
 8
 9 import fileinput
10
11
12 def rewrite_line(filename, lineno, text, left=True,right=False):
13    f= fileinput.input(filename, inplace=1)
14    for linein f:
15        line_text= line.replace("\r\n","").replace("\n", "")
16        if f.lineno()== lineno:
17            if left:
18                print text+ line_text
19            elif right:
20                print line_text+ text
21            else:
22                print text
23        else:
24            print line_text
25    f.close()
26
27 def cat(filename):
28    with file(filename)as f:
29        print f.read()
30    os.remove(filename)
31    with file(filename,"w")as f:
32        f.write("a\nb\nc")
33
34 def test():
35    filename= "rewrite.test"
36    with file(filename,"w")as f:
37        f.write("a\nb\nc")
38
39    print "newfile:" + filename
40    print "filecontent: a\nb\nc"
41
42    print "--------starttest---------"
43
44    print filename,"line:", 2, "left add # --> #b?"
45    rewrite_line(filename,2, "#", left=True)
46    cat(filename)
47
48
49    print filename,"line:", 2, "right add #END --> b#END?"
50    rewrite_line(filename,2, "#END", left=False,right=True)
51    cat(filename)
52
53    print filename,"line:", 1, " rewrite a --> zhipeng?"
54    rewrite_line(filename,1, "zhipeng", left=False,right=False)
55    cat(filename)
56
57    os.remove(filename)
58
59
60 if __name__ == "__main__":
61    test()
-

参考：《how-to-write-char-on-line-into-file》《http://stackoverflow.com/questions/5453267/is-it-possible-to-modify-lines-in-a-file-in-place》《Python fileinput模块》

输出如下：

new file:rewrite.test

file content: a

b

c

--------start test---------

rewrite.test line: 2 left add # --> #b?

a

#b

c

rewrite.test line: 2 right add #END --> b#END?

a

b#END

c

rewrite.test line: 1  rewrite a -->zhipeng?

zhipeng

b

c

根据输出可以看到，函数rewrite_line中的print的每行值并没有打印出来，而是打印到stdout中，其实就是直接定向到文件了，这样做，可能有点鸡肋吧。。。但起码也是一个轮子