When a system uses a text-only shell prompt, you should know how to use at least one text editor for editing files. You can then edit text-based configuration files from a terminal window or remote logins through the ssh command or the Web Console. You also do not need access to a graphical desktop to edit files on a server, and that server might not need to run a graphical desktop environment.

The key reason to learn Vim is that it is almost always installed by default on a server for editing text-based files. The Portable Operating System Interface or POSIX standard specified the vi editor on Linux, and many other UNIX-like operating systems largely do likewise.

Vim is also used often as the vi implementation on other standard operating systems or distributions. For example, macOS currently includes a lightweight installation of Vim by default. So, Vim skills that are learned for Linux might also prove useful elsewhere.

You can install the Vim editor in Red Hat Enterprise Linux by using either of two packages. These two packages provide different features and Vim commands for editing text-based files.

With the vim-minimal package, you might install the vi editor with core features. This lightweight installation includes only the core features and the basic vi command. You can open a file for editing by using the vi command:

[user@host ~]$ vi filename

Alternatively, you can use the vim-enhanced package to install the Vim editor. This package provides a more comprehensive set of features, an online help system, and a tutorial program. Use the vim command to start Vim in this enhanced mode:

[user@host ~]$ vim filename

The core features of the Vim editor are available in both commands.

If vim-enhanced is installed, then a shell alias is set so that if regular users run the vi command, then they automatically get the vim command instead. This alias does not apply to the root user and to other users with UIDs below 200 (which system services use).

If vim-enhanced is installed and a regular user wants to use the vi command, then they might have to use the \vi command to override the alias temporarily. You can use \vi --version and vim --version to compare the feature sets of the two commands.

The Vim editor offers various modes of operation such as command mode, extended command mode, edit mode, and visual mode. As a Vim user, always verify the current mode, because the effect of keystrokes varies between modes.

Figure 1.1: Moving between Vim modes

When you first open Vim, it starts in command mode, which is used for navigation, cut and paste, and other text modification. Pressing the required keystroke accesses specific editing functions.

Vim has efficient, coordinated keystrokes for advanced editing tasks. Although considered beneficial with practice, the capabilities of Vim can overwhelm new users.

Red Hat recommends that you learn the following Vim keys and commands:

Learning these commands helps a Vim user to accomplish any editing task.

In Vim, you can yank and put (copy and paste), by using the y and p command characters. Position the cursor on the first character to select, and then enter visual mode. Use the arrow keys to expand the visual selection. When ready, press y to yank the selection into memory. Position the cursor at the new location, and then press p to put the selection at the cursor.

Visual mode is useful to highlight and manipulate text in different lines and columns. You can enter various visual modes in Vim by using the following key combinations.

Character mode highlights sentences in a block of text. The word VISUAL appears at the bottom of the screen. Press v to enter visual character mode. Shift+v enters line mode. VISUAL LINE appears at the bottom of the screen.

Visual block mode is perfect for manipulating data files. Press the Ctrl+v keystroke to enter the visual block from the cursor. VISUAL BLOCK appears at the bottom of the screen. Use the arrow keys to highlight the section to change.

The /etc/vimrc and ~/.vimrc configuration files alter the behavior of the vim editor for the entire system or for a specific user respectively. Within these configuration files, you can specify behavior such as the default tab spacing, syntax highlighting, color schemes, and more. Modifying the behavior of the vim editor is particularly useful when working with languages such as YAML, which have strict syntax requirements. Consider the following ~/.vimrc file, which sets the default tab stop (denoted by the ts characters) to two spaces while editing YAML files. The file also includes the set number parameter to display line numbers while editing all files.

[user@host ~]$ cat ~/.vimrc
autocmd FileType yaml setlocal ts=2
set number

A complete list of vimrc configuration options is available in the references.