Regular expression (regex) reference. Regular expressions can be used in conjunction with Pexip Infinity features including Call Routing Rule s, Provisioning VMRs, devices and users from Active Directory via LDAP and searching the support and admin logs. Regular Expressions Quick Reference. This quick reference is a summary of all the regex syntax that is listed in the full reference tables, without any explanation. You can use this table if you’ve seen some syntax in somebody else’s regex and you have no idea what feature that syntax is for. Project framework 1. Initialization project gridsome create my-blog cd my-blog gridsome develop If the first stepcreateErrors are reported or take a long time in the installation dependency. Highly recommended for anyone interested in the internals of regular expression engines, and a good introduction to the theory. Description . The regular expressions accepted by regexp and regsub are called "Advanced Regular Expressions'', or ARE's, and are slightly different from the extended regular expressions's defined by POSIX.