From the course: Bash Patterns and Regular Expressions
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Performance optimizing grep searches - Bash Tutorial
From the course: Bash Patterns and Regular Expressions
Performance optimizing grep searches
- There can be a big difference in speed when using Grep depending on a few things. In Chapter one of this course, we talked about changing the locale setting to make sorting more consistent. There can be a large speed increase when the shell colation is set to a single bite locale such as C. Also, Grep is tuned to the C locale. When you're not using the C locale, character set ranges and colation equivalencies can be quite slow. Avoid them if possible. Backreferences can be slow, because that forces the search algorithm to backtrack through the data that's being processed. Case insensitivity is slow. Use a character set, listing the least amount of upper and lower case characters possible. Multiple simple searches can be faster than one complex search. Grep uses the Boyer-Moore fast string searching algorithm when matching a single fixed pattern, and the Aho-Corasick algorithm if used to match multiple fixed patterns. Matching one fixed pattern and piping it back into Grep and…
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