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Changing strings in files


On 10/11/2020 5:24 pm, Manfred Lotz wrote:
> I have a situation where in a directory tree I want to change a certain
> string in all files where that string occurs.
>
> My idea was to do
>
> - os.scandir and for each file
>     - check if a file is a text file
>     - if it is not a text file skip that file
>     - change the string as often as it occurs in that file
>
>
> What is the best way to check if a file is a text file? In a script I
> could use the `file` command which is not ideal as I have to grep the
> result. In Perl I could do  -T file.
>
> How to do best in Python?
Not necessarily best but I rolled this earlier. Much earlier. But I 
still use it. I don't need to worry about text files or binary because I 
specify .py files.

  

# -*- coding: utf-8 -*-
"""
Look for string 'find' and replace it with string 'repl' in all files in the
current directory and all sub-dirs.

If anything untoward happens, laboriously retrieve each original file from each
individual backup made by suffixing ~ to the filename.

If everything went well, make find == repl and run again to remove backups.

"""
import os

find = """# Copyright (c) 2019 Xyz Pty Ltd"""

repl = """# Copyright (c) 2020 Xyz Pty Ltd"""

ii = 0
kk = 0
for dirpath, dirnames, filenames in os.walk(".", topdown=True):
     if "migrations" in dirpath:
         continue
     for filename in filenames:
         if filename.endswith(".py"):  # or filename.endswith(".txt"):
             fil = os.path.join(dirpath, filename)
             bak = "{0}~".format(fil)
             if find == repl:
                 if os.path.isfile(bak):
                     ii += 1
                     os.remove(bak)
             else:
                 with open(fil, "r") as src:
                     lines = src.readlines()
                     # make a backup file
                     with open(bak, "w", encoding="utf-8") as dst:
                         for line in lines:
                             dst.write(line)
                 with open(bak, "r") as src:
                     lines = src.readlines()
                     # re-write the original src
                     with open(fil, "w", encoding="utf-8") as dst:
                         kk += 1
                         for line in lines:
                             dst.write(line.replace(find, repl))
print("\nbak deletions = %s, tried = %s\n" % (ii, kk))


  





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