是否可以修改文件中的行？ [英] Is it possible to modify lines in a file in-place?

问题描述

有没有可能一行一行地解析一个文件，并在通过这些行的同时编辑一个行？

解决方案

< blockquote>

是否可以逐行解析一个文件，并在编辑行的同时进行编辑？

可以使用备份文件模拟stdlib的 fileinput <



下面是一个示例脚本，用于删除不满足 some_condition 从命令行给出的文件或 stdin ：

 ＃ ！/ usr / bin / env python 
＃grep_some_condition.py 
 import fileinput 
 $ b $ for line in fileinput.input（inplace = True，backup ='。bak'）：
如果some_condition（line）：
 print line，＃this goes to the current file 
  

例子：



  $ python grep_so me_condition.py first_file.txt second_file.txt 
  

完成 first_file.txt 和 second_file.txt 文件将仅包含满足 some_condition（）谓词的行。 p>


Is it possible to parse a file line by line, and edit a line in-place while going through the lines?

解决方案

Is it possible to parse a file line by line, and edit a line in-place while going through the lines?

It can be simulated using a backup file as stdlib's fileinput module does.

Here's an example script that removes lines that do not satisfy some_condition from files given on the command line or stdin:

#!/usr/bin/env python
# grep_some_condition.py
import fileinput

for line in fileinput.input(inplace=True, backup='.bak'):
    if some_condition(line):
        print line, # this goes to the current file

Example:

$ python grep_some_condition.py first_file.txt second_file.txt

On completion first_file.txt and second_file.txt files will contain only lines that satisfy some_condition() predicate.

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