Monthly Archives: September 2016

UNIX tip of the day – grep -P is slow

Unless you really need some advanced regular expressions only supported by PCRE, using POSIX regular expressions with grep is usually an order of magnitude faster – that’s because the default engine with grep uses finite automata, as opposed to a backtracking algorithm which PCRE uses ( the main featuress you gain from the backtracking algorithm […]

Posted in perl, regex, UNIX | Comments Off on UNIX tip of the day – grep -P is slow