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Master reference for everything UNIX and command line. Complete summary covering file systems, text processing, pipes, processes, permissions, shell scripting, and a comprehensive command glossary. Your one-stop resource for all UNIX topics in Data Management.

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UNIX Philosophy

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Core principle: Do one thing well. Programs work together via text streams.

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Three Key Principles

1. Do one thing well - Each tool has a single, focused purpose
2. Work together - Tools communicate via text streams using pipes
3. Handle text streams - Plain text is the universal interface

Why it matters: Simple tools combined create powerful solutions. grep | sort | uniq | wc beats writing custom code.

File System Fundamentals

File System Structure

UNIX uses a tree-like structure starting from root /:

/  (root)
├── home/        # User home directories
├── etc/         # Configuration files
├── var/         # Variable data (logs)
├── bin/         # Essential binaries
├── usr/bin/     # User binaries
└── tmp/         # Temporary files

Path Types

Absolute paths - Start from root /

/home/student/documents/file.txt

Relative paths - From current location

../faculty/files/data.csv
./[script.sh](<http://script.sh>)