regex - How do I search and replace across multiple lines with Perl?

Question

$ perl --version
This is perl, v5.10.1 (*) built for x86_64-linux-gnu-thread-multi

$ echo -e "foo
bar" > baz.txt
$ perl -p -e 's/foo
bar/FOO
BAR/m' baz.txt
foo
bar

How can I get this replacement to work?

Answer 1

You can use the -0 switch to change the input separator:

perl -0777pe 's/foo
bar/FOO
BAR/' baz.txt

-0777 sets the separator to undef, -0 alone sets it to which might work for text files not containing the null byte.

Note that /m is needless as the regex does not contain ^ nor $.