Regex for PCRE, grep, ripgrep, and sed/Alternation in egrep style

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Section: grep, egrep, and ripgrep

Alternation in egrep style

bash
bash
grep -E 'warn|error|fatal' app.log
Explanation

`grep -E` enables extended regular expressions.

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

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