How does regular expressions in grep work internally in Linux?

Regular expressions in grep are powerful tools used for searching text patterns within files. Internally, grep utilizes finite state machines to process regular expressions, allowing it to efficiently match patterns in large text streams.

When you run a grep command, it compiles the regular expression into a deterministic finite automaton (DFA), which enables it to scan through text data and identify matches in a single pass, making it faster than many naive matching algorithms.

Here's an example of a grep command using a regular expression:

grep '^[A-Za-z]' filename.txt

grep regular expressions text search finite state machines pattern matching

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