Word and Excel and PowerPoint and other Microsoft programs have intimate — one might say promiscuous — knowledge of each others' internals. In Unix, one tries to design programs to operate not specifically with each other, but with programs as yet unthought of.

— Douglas McIlroy, The Art of Unix Programming (2003)

Source: http://www.catb.org/esr/writings/taoup/html/ch01s06.html

From the "The Elements of Operating-System Style" chapter (2003).

Topics: software design, unix