Is there any necessary program for inserting words?

Question

Text Processing Automation

Suppose there are 100 texts in text files of the form (example of one text):

[some text]key[some text][some text]key[some text]
[some text]key[some text] then text][some text]key[some text]

Is there any program that will automatically replace the words of my phrases instead of the word key in all files. And in one file (where there are several words key) only one of my phrases will be inserted. And so in all files there are different phrases (in my case, keywords)).

Answer 1

Notepad++ with regexps.