🔗 Pipelines

Pipes (|) connect the output of one command to the input of another, forming powerful chains of operations.

🔗 How Pipes Work

Syntax:

command1 | command2 | command3

Data flows left to right: 1. command1 writes to stdout 2. Pipe connects stdout of command1 to stdin of command2 3. And so on...

Example:

$ ps aux | grep nginx

Finds all processes matching "nginx".

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🧪 Real-World Pipeline Examples

Count number of files:

$ ls | wc -l

Sort unique IP addresses from logs:

$ awk '{print $1}' access.log | sort | uniq

Filter JSON logs by field value:

$ jq -r '.timestamp' logs.json | sort

Process CSV columns:

$ cut -d',' -f2 data.csv | sort | uniq -c

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🧠 Behind the Scenes

Each stage runs in a subshell concurrently. The kernel handles buffering and synchronization automatically.

However: - Large outputs may cause temporary slowdowns. - Too many stages increase complexity and reduce readability.

Best practice: Keep pipelines short and focused.

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🧾 Summary

• Pipes chain commands together seamlessly.
• Each command receives input from previous one.
• Useful for filtering, transforming, aggregating data.
• Can become unwieldy if too long — keep readable.

👉 Continue to: Variables and Environment