Physical-line-mode.el provides a mechanism to move the cursor across "physical lines", which are actual lines displayed on your Emacs screen. Usually Emacs takes a line as "logical" one, which is defined as a string between two newline characters. So if you type C-p (or C-n) on a sentence which stretches for several lines, it seems to skip the part you really want to move to. Physical-line-mode.el makes your Emacs recognize physical lines correctly in the following commands: previous-line, next-line, beginning-of-line, end-of-line.
My name is hoge. に対して sed -e 's/is/are/' のようなことはできますか？ (my-sed "My name is hoge." "s/is/are/") みたいに。 emacs lisp リファレンスマニュアルに perform-replace や replace-match というのがありましたが、この辺りにサンプルコードが全く書いて無いし 引数も多いので使い方が全く分かりません。