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I use grep to find a string in a text file, but got nothing
and the message is binary file matches

And it should show some matches. If i open the txt-file with kate and search, I find it.

Grep thinks that it is binary file for some reason,
and doesn't process it.
Maybe there are some special characters in the txt file.

You can solve it by forcing:
grep --text
grep -a
or grep --binary-files=text