The Unix philosophy emphasizes building simple, short, clear, modular, and extensible code that can be easily maintained and repurposed by developers other than its creators. Make each program do one how do i separate one page from a pdf well.

To do a new job, build afresh rather than complicate old programs by adding new “features”. Expect the output of every program to become the input to another, as yet unknown, program. Don’t clutter output with extraneous information. Avoid stringently columnar or binary input formats. Don’t insist on interactive input. Design and build software, even operating systems, to be tried early, ideally within weeks.

Don’t hesitate to throw away the clumsy parts and rebuild them. Use tools in preference to unskilled help to lighten a programming task, even if you have to detour to build the tools and expect to throw some of them out after you’ve finished using them. 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.

Even though the UNIX system introduces a number of innovative programs and techniques, no single program or idea makes it work well. Instead, what makes it effective is the approach to programming, a philosophy of using the computer. Although that philosophy can’t be written down in a single sentence, at its heart is the idea that the power of a system comes more from the relationships among programs than from the programs themselves. Many UNIX programs do quite trivial things in isolation, but, combined with other programs, become general and useful tools.

The authors further write that their goal for this book is “to communicate the UNIX programming philosophy. Much of the power of the UNIX operating system comes from a style of program design that makes programs easy to use and, more important, easy to combine with other programs. Other commands are used for other functions. For example, there are separate commands for file system tasks like renaming files, deleting them, or telling how big they are. Other systems instead lump these into a single “file system” command with an internal structure and command language of its own.