Group host(?P<host>\d+(?:\.\d+){3}) \d+a Unicode decimal digit, repeated at least once
Non-Capturing Group(?:\.\d+){3} {3}repeats the group contents below exactly 3 times:
\.the literal . (4610 / 568 / 2E16)
\d+a Unicode decimal digit, repeated at least once
\s+a Unicode whitespace character, repeated at least once
\S+any character that is not Unicode whitespace, repeated at least once
\s+a Unicode whitespace character, repeated at least once
Group user_name(?P<user_name>\S+) \S+any character that is not Unicode whitespace, repeated at least once
\s+a Unicode whitespace character, repeated at least once
\[the literal [ (9110 / 1338 / 5B16)
Group time(?P<time>[^\]\[]*) Negated Character Class[^\]\[]* *matches any number of characters outside the set below:
\]the literal ] (9310 / 1358 / 5D16)
\[the literal [ (9110 / 1338 / 5B16)
\]the literal ] (9310 / 1358 / 5D16)
\s+a Unicode whitespace character, repeated at least once
Group request(?P<request>[^"]*) Negated Character Class[^"]* *matches any number of characters outside the set below:
"the literal " (3410 / 428 / 2216)
"the literal " (3410 / 428 / 2216)
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string
x modifier: extended. Ignores unescaped whitespace and comments outside character classes