Program design in the UNIX environment

Rob Pike ** cat -v considered harmful UNIX 7th edition introduced the first optional argument -u to cat BSD cat added -v (make non printing characters visible) among other arguments ** cat’s job is to collect the data, not change it create a program named vis instead options like -ve (mark ends of lines), -vt (change representation of tab) in cat should be options in vis in practice cat is used with no options and faster because it can process data in large blocks instead of byte-at-time ** dealing with fast terminal lines Berkeley’s version of the ls command behaves differently if out is a pipe or a terminal. If it is a terminal, automatically prints in columns. This is built-in to ls and not inaccessible to other programs. There should be a separate program for columnation ** history mechanism, editor escape as a function of the terminal Blit uses a mouse to point to characters on the display, which can be edited, rearranged, and transmitted back to the UNIX system Removes the need for interactive features in programs ** problem solving on UNIX Identify the right primitive operations and put them in the right place.