103.8 Lesson 1

The insert mode is straightforward: text appears on the screen as it is typed on the keyboard. It is the type of interaction most users expect from a text editor, but it is not how vi first presents a document. To enter the insert mode, the user must execute an insertion command in the normal mode. The Esc key finishes the insert mode and returns to normal mode, the default vi mode.

Normal mode — also known as command mode — is how vi starts by default. In this mode, keyboard keys are associated with commands for navigation and text manipulation tasks. Most commands in this mode are unique keys. Some of the keys and their functions on normal mode are:

If preceded by a number, the command will be executed the same number of times. For example, press 3yy to copy the current line plus the following two, press d5w to delete the current word and the following 4 words, and so on.

Most editing tasks are combinations of multiple commands. For example, the key sequence vey is used to copy a selection starting at the current position until the end of the current word. Command repetition can also be used in combinations, so v3ey would copy a selection starting at the current position until the end of the third word from there.

vi can organize copied text in registers, allowing to keep distinct contents at the same time. A register is specified by a character preceded by " and once created it’s kept until the end of the current session. The key sequence "ly creates a register containing the current selection, which will be accessible through the key l. Then, the register l may be pasted with "lp.

There is also a way to set custom marks at arbitrary positions along the text, making it easier to quickly jump between them. Marks are created by pressing the key m and then a key to address the current position. With that done, the cursor will come back to the marked position when ' followed by the chosen key are pressed.

Any key sequence can be recorded as a macro for future execution. A macro can be recorded, for example, to surround a selected text in double-quotes. First, a string of text is selected and the key q is pressed, followed by a register key to associate the macro with, like d. The line recording @d will appear in the footer line, indicating that the recording is on. It is assumed that some text is already selected, so the first command is x to remove (and automatically copy) the selected text. The key i is pressed to insert two double quotes at the current position, then Esc returns to normal mode. The last command is P, to re-insert the deleted selection just before the last double-quote. Pressing q again will end the recording. Now, a macro consisting of key sequence x, i, "", Esc and P will execute every time keys @d are pressed in normal mode, where d is the register key associated with the macro.

However, the macro will be available only during the current session. To make macros persistent, they should be stored in the configuration file. As most modern distributions use vim as the vi compatible editor, the user’s configuration file is ~/.vimrc. Inside ~/.vimrc, the line let @d = 'xi""^[P' will set the register d to the key sequence inside single-quotes. The same register previously assigned to a macro can be used to paste its key sequence.

The normal mode also supports another set of vi commands: the colon commands. Colon commands, as the name implies, are executed after pressing the colon key : in normal mode. Colon commands allow the user to perform searches, to save, to quit, to run shell commands, to change vi settings, etc. To go back to the normal mode, the command :visual must be executed or the Enter key pressed without any command. Some of the most common colon commands are indicated here (the initial is not part of the command):

The standard vi program is capable of doing most text editing tasks, but any other non-graphical editor can be used to edit text files in the shell environment.

Users unfamiliar with vi may have difficulties adapting to it, since its operation is not intuitive. A simpler alternative is GNU nano, a small text editor that offers all basic text editing features like undo/redo, syntax coloring, interactive search-and-replace, auto-indentation, line numbers, word completion, file locking, backup files, and internationalization support. Unlike vi, all key presses are just inserted in the document being edited. Commands in nano are given by using the Ctrl key or the Meta key (depending on the system, Meta is Alt or ⌘).

Emacs is another very popular text editor for the shell environment. Whilst text is inserted just by typing it, like in nano, navigation through the document is assisted by keyboard commands, like in vi. Emacs includes many features that makes it more than just a text editor. It is also an IDE (integrated development environment) capable of compiling, running, and testing programs. Emacs can be configured as an email, news or RSS client, making it an authentic productivity suite.

The shell itself will run a default text editor, usually vi, every time it is necessary. This is the case, for example, when crontab -e is executed to edit cronjobs. Bash uses the session variables VISUAL or EDITOR to find out the default text editor for the shell environment. For example, the command export EDITOR=nano defines nano as the default text editor in the current shell session. To make this change persistent across sessions, the command should be included in ~/.bash_profile.