I have a problem with what I think is a difference in grep's regex and perl's regex. Consider the following little test:

$ cat testfile.txt 
A line of text
SOME_RULE = $(BIN)
Another line of text

$ grep "SOME_RULE\s*=\s*\$(BIN)" testfile.txt 
SOME_RULE = $(BIN)

$ perl -p -e "s/SOME_RULE\s*=\s*\$(BIN)/Hello/g" testfile.txt
A line of text
SOME_RULE = $(BIN)
Another line of text

As you can see, using the regex "SOME_RULE\s*=\s*$(BIN)", grep could find the match, but perl was unable to update the file using the same expression. How should I solve this problem?

regex perl grep
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