Great for parsing…
Match a block:
^(line vty (.*))\n( .*\n)*
Match a command within a block:
^(line vty (.*))\n( .*\n)( access-class (.*))\n
Match multiple strings within a command within a block:
^(line vty (.*))\n( .*\n)*( access-class (\S+) (\S+))\n
Match command output from “show cdp neighbor”
^\S*\s*(\S*)\s*(\S*)\s*.*IP Phone.*
regex