If you regularly use the Terminal in OS X, then you may be happy to know one feature that will likely make it into the final release of OS X Yosemite is the ability to scroll through multiple lines of text in the Terminal.
In OS X Mavericks and earlier, standard output from the Terminal is stored in its scrollback buffer, which allows you to move back and see previous commands and their respective output by using page up and page down, as well as standard scrolling. However, if you open a program such as a text editor that displays content on multiple pages, then this ability to easily scroll will not be available and you will have to use arrows and other keys to view additional content.
For example, if you enter “man top” to open a standard manual page for the “top” command, you will see the first part of the manual page as expected, and then have to view anything else outside of the Terminal’s window by navigating with your keyboard. In Yosemite, Apple has added a feature where by scrolling up and down you will rapidly move your cursor up or down by one line. This will in effect allow you to scroll in text editors like pico, vi, and emacs, but also in many other programs. A couple of programs where this may be useful are the “less” command for limiting standard output to a single page at a time, and the Unix “man” pages (which invoke “less” by default).
With this new scrolling feature, you will be able to move up and down through pages of code, configuration files, instructions, and other content in the Terminal, without having to use key-presses. In essence, if you can move the Terminal’s input cursor up and down in your content with the arrow keys, then you will be able to use this feature to scroll.
Even though this feature allows you to scroll through the lines of a current document, you can still scroll up through the standard scrollback buffer by holding the Shift key while scrolling. For instance, if you have a text document open in pico and can see pico’s tools and menus, standard scrolling will move your cursor up and down in pico, but holding the Shift key will move the pico interface down and reveal the past command history and other standard output shown in the Terminal before you opened the pico program.
For anyone who regularly looks up man page information or who views lengthy configuration and code files in the Terminal, this feature should greatly increase your ability to get your work done, especially since by scrolling on a per-line basis, this will place your cursor wherever you scroll to. You can then use the arrow keys to more finely place the cursor where you want, or hold the Option key to click a specific character to have the Terminal place the cursor right where you clicked.