In the beginning, there was the command line...

The command line was great and powerful, but unfulfilling for some tasks. Perhaps the most important of these tasks was editing text files, something UNIX was used for frequently in the early days. One of the original uses of the earliest UNIX systems was to author official AT&T publications, hence the Documenter's Workbench (see the Heirloom Documentation Tools page for more information).

The "standard" editor on UNIX was ed, an ancient, untamable beast; a line editor. For the longest time, ed was the only text editor that was guaranteed to be present on any given UNIX system, and almost certainly the only one available in single user mode, for fixing broken things.

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Over the last 15 years, UNIX has quietly evolved into something like UNIX but not UNIX.

In fact, one of the reasons I'm interested in Ancient UNIX is to remind me of and teach me the original UNIX philosophy, which among other things says:

This is the Unix philosophy: Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface.

The above is a summary attributed to Doug McIlroy, but there are books devoted to the philosophy.

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