A regular expression used to parse the output of the Version Check Command. Capturing group(s) must be used to identify the version itself.
e.g. for git, the command
"git --version"
outputs a string of the form
"git version 1.2.3"
so would need a regular expression
"git version ([0-9.]*)"
in order to obtain the version "1.2.3".
If this is left blank (the default) then no version check will be performed.