Can I break the long line in emacs (non windows) to the next line?

You can customize the word-wrap variable to visually wrap lines. This should be similar to longlines-mode, except it would use the buffer width rather than the fill column for wrapping.

You can alternatively use visual-line-mode to both enable word wrapping, and also "Redefine simple editing commands to act on visual lines, not logical lines", which addresses a point that nominolo mentioned.

You can get emacs to break long lines into multiple shorter lines with M-x fill-paragraph or M-x fill-region. You can also make this the default behavior with M-x auto-fill-mode.

You can disable line truncation with M-x set-variable truncate-lines nil.

You can also put in your .emacs (setq-default truncate-lines nil) to have that setting by default.