Korn Shell Programming by Example

Where vi Came From

UNIX editors have gone through an evolutionary process. The first UNIX editor was the ed editor. It was strictly a line-oriented editor (as opposed to a screen-oriented editor like vi). It still exists in most UNIX variants, but it has been relegated to special-case use. As an example, if your UNIX runs in single-user mode, the editor that tends to be used by a utility with an edit subfunction, at that time, is the ed editor. Single-user mode is usually entered to accomplish some specialized system admin task. While in single-user mode, the only file system that is mounted is the root file system (unless the administrator specifically mounts other file systems).

The vi editor program has been linked against shared libraries, ...