Changing strings in files

[Manfred Lotz]

On Tue, 10 Nov 2020 18:52:26 +1100
Mike Dewhirst <miked at dewhirst.com.au> wrote:

> 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))
> 
> 

Thanks, will take a look.

-- 
Manfred