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while (my $line = <FILE>) {
        $line =~ s/$curUrl/$tarUrl/g;
    }

open my $INFILE, '<', 'some_file'
    or die "Couldn't open $fname: $!";

{
    local $^I = ".backup";
...
        print;
    }
}

...
use English '-no_match_vars';
...
        print;
    }
}

$^I = undef;  #default value, Turn off inplace editing mode.

$^I = "some_string";  #Turn on inplace editing mode, use "some_string"
                      #as the extension for the backup files.

$^I = "";           #Turn on inplace editing mode, delete backup files
+.