Changing strings in files

[Loris Bennett]

Manfred Lotz <ml_news at posteo.de> writes:

> On Tue, 10 Nov 2020 08:19:55 +0100
> "Loris Bennett" <loris.bennett at fu-berlin.de> wrote:
>
>> Manfred Lotz <ml_news at posteo.de> writes:
>> 
>> > 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?  
>> 
>> If you are on Linux and more interested in the result than the
>> programming exercise, I would suggest the following non-Python
>> solution:
>> 
>>    find . -type -f -exec sed -i 's/foo/bar/g' {} \;
>> 
>
> My existing script in Perl which I wanted to migrate to Python I used 
>  `-T $file` and called sed
>
> I like the -T which I assume does some heuristics to tell me if a file
> is a text file. 

Sorry, I missed the bit about text files.  By '-T' I assume you mean
Perl's taint mode option.  I am no security expert, but as I understand
it, taint mode does more than just check whether something is a text
file, although the "more" probably applies mainly to files which contain
Perl code.

Sorry also to bang on about non-Python solutions but you could do

  find . -type f -exec grep -Iq . {} \; -and -exec sed -i 's/foo/bar/g' {} \;

i.e. let grep ignore binary files and quietly match all non-binary files.

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