perl -p -i -e "s/\n//g" file.html
EDIT Actually, that might act weird with the
\n in there. Another approach is to take advantage of Bash's string concatenation. これはうまくいくはずです：
perl -p -i -e 's/\n//g' file.html
EDIT 2: I just took a closer look at what you're trying to do, and it's kind of dangerous. You're using the greedy form of
.*, which could match a lot more text than you want. Use
.*? instead. I updated the above regexes.