The software on GNU/Linux mostly adheres to the "Unix philosophy".
While people tend to disagree on what that means exactly, it usually
denotes a set of guidelines for writing simple, compact, modular,
reusable, compositable programs that work with each other to
solve more complex tasks.
For example, in 1986 Jon Bentley posed the challenge:
Read a file of text, determine the n most frequently
used words, and print out a sorted list of those words
along with their frequencies.
Donald Knuth's solution was an elaborate program spanning two pages in
a Pascal-like programming language. It worked. But Doug Mcllroy's 6-line
solution shows the power of the Unix philosophy:
tr --complement --squeze-repeats A-Za-z '\\n'
| tr A-Z a-z
| sort
| uniq --count
| sort --reverse --numeric-sort
| sed ${1}q
To learn more about the Unix philosophy, see the Unix philosophy
Wikipedia article, the List of standard Unix utilities (including those
from the short program above), or read some of these witty Unix koans.
Wan to learn the ways of the Unix command line? Try one of these free
online tutorials.