This one Linux shell character made me feel like a hacker
This one Linux shell character made me feel like a hacker
https://tech.yahoo.com/computing/articles/one-linux-shell-character-made-113016289.html
Publish Date: 2026-03-28 07:30:00
Source Domain: tech.yahoo.com
Like many people using Unix-like operating systems for the first time, I was introduced to the concept of the pipeline. Here’s how a single character on the command line changed everything.
What is the pipe (|) character?
Building programs from other programs
The pipleline character, or |, sends the output of one Linux command to the input of another. It was originally developed at Bell Labs in the early 1970s. I was introduced to this in a book on Unix on what was then called “Mac OS X.” This simple character changed everything.
A good example of a pipeline is searching the output of a program for some string. Suppose I wanted to find out which processes on the system belonged to root. I would display all of the processes running on the system with the “ps aux” command and send that output to grep, searching for “root”
ps aux | grep root
The concept was invented by Doug McIllroy. At the time, Unix was actually considered user-friendly because you typed commands into a terminal instead of punching up a deck of computer cards to hand to an operator in the computer center and wait to receive your results (and your inevitable errors).
The latter was called “batch mode,” and it was how mainframe computers were used since their inception.
Pipelines make use of a concept in Unix and modern Linux systems of “standard input/output.” The standard input is the keyboard, and the standard output is the terminal. There’s also a “standard error” for error messages. This is also the terminal. You can “redirect” standard input. I’d seen this concept when trying to follow along with a C++ book, but it made a lot more sense to me when I started using the Linux command line.
You can save the output to a file for later with the (greater than) symbol:
ps aux allprocs
Or you can feed the contents of a file to another program with the
cat
The “software tools” idea
The vibe coding of the ’70s?
This approach might be simple, but it was a kind of manifesto. Instead of building monolithic programs,…
