Processes, Pipes and Filters

Learn how to connect Unix programs together using pipes and filters. Build powerful data processing pipelines by chaining simple commands. Core Unix philosophy: each program does one thing well and can talk to others.

At-a-glance checklist

Understand the three standard I/O streams: stdin, stdout, stderr
Master the pipe operator (|) to connect program outputs to inputs
Use input/output redirection (<, >, >>) to work with files
Learn essential filters: head, tail, sort, uniq, wc, cut
Remember: uniq requires sorted input - always sort first!
Use cut with -f (field) and -d (delimiter) to extract CSV columns
Build complex pipelines by chaining simple commands together
Practice with real datasets (Airbnb NYC listings)
All piped programs run concurrently - OS handles parallelization

Key takeaways

The power: Connect simple programs to do complex tasks - grep, sort, uniq, wc working together beats writing custom code.

Critical rule: Always sort before uniq - it only removes adjacent duplicates.

Efficiency: Each program does ONE thing well (Unix philosophy), then pipes let you combine them into powerful workflows.

Real-world: Process CSV files, extract columns, count unique values, filter data - all without writing a single line of code.