All regular expressions are in PCRE format.
For web application form authentication, the regular expression must match a pattern on a page that is not accessible to an unauthenticated user. A good choice may be a "logout" link that is displayed only when the user has successfully authenticated. You can enter a maximum of 1024 characters.
No bounding delimiters are necessary, the entire string is considered the regex. This means that syntax like /foo/ or #foo# is not required. The / or # characters familiar in Perl or Python are needed for those languages to delimit the regex; we don't need those delimiters.
Only standard PCRE metacharacters need to be escaped:
\s -- space character
\w -- word character
\\ -- literal backslash Or escaping metacharacters to match a literal character
\. -- match a dot rather than anything
\? -- match a question mark rather than interpret it as a 0 or 1 quantifier Some more examples
Admin -- match the word Admin anywhere
.* -- match anything 0 or more times
a+ -- match the letter 'a' one or more times
successful\slogin -- match "successful login" separated by a space, tab, or new line
^response$ -- match the word response, with anchors to the beginning and end of the input
Note: The characters # and / are not acceptable in regular expressions.