Linux Text Processing Cheat Sheet/Pipe file content into grep

Basic pipeline for filtering text from a file.

Section: Overview and Core Patterns

Pipe file content into grep

bash
bash
cat app.log | grep ERROR
Explanation

Use a pipeline to send command output into another command for filtering or transformation.

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Compare similar commands or jump into common fixes when this command is part of a bigger troubleshooting path.

Related commands

Same sheet · prioritizing Overview and Core Patterns
Search a file directly
Prefer direct file arguments when possible.
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Read from standard input
Many text tools consume stdin naturally.
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Save output and continue pipeline
Write output to a file while still passing it downstream.
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Split a long pipeline across lines
Use backslashes for readability.
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Show first 20 lines
Preview the top of a file.
Squeeze repeated spaces
Collapse multiple spaces into one.