ngx.re.matchsyntax: captures, err = ngx.re.match(subject, regex, options?, ctx?, res_table?)context: init_worker_by_lua*, set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua*, ngx.timer.*, balancer_by_lua*, ssl_certificate_by_lua*, ssl_session_fetch_by_lua*, ssl_session_store_by_lua*Matches the subject string using the Perl compatible regular expression regex with the optional options.Only the first occurrence of the match is returned, or nil if no match is found. In case of errors, like seeing a bad regular expression or exceeding the PCRE stack limit, nil and a string describing the error will be returned.When a match is found, a Lua table captures is returned, where captures[0] holds the whole substring being matched, and captures[1] holds the first parenthesized sub-pattern's capturing, captures[2] the second, and so on. local m, err = ngx.re.match("hello, 1234", "[0-9]+") if m then     -- m[0] == "1234" else     if err then         ngx.log(ngx.ERR, "error: ", err)         return     end     ngx.say("match not found") end local m, err = ngx.re.match("hello, 1234", "([0-9])[0-9]+") -- m[0] == "1234" -- m[1] == "1"Named captures are also supported since the v0.7.14 release and are returned in the same Lua table as key-value pairs as the numbered captures. local m, err = ngx.re.match("hello, 1234", "([0-9])(?
    
     [0-9]+)") -- m[0] == "1234" -- m[1] == "1" -- m[2] == "234" -- m["remaining"] == "234"Unmatched subpatterns will have false values in their captures table fields. local m, err = ngx.re.match("hello, world", "(world)|(hello)|(?
     
      howdy)") -- m[0] == "hello" -- m[1] == false -- m[2] == "hello" -- m[3] == false -- m["named"] == falseSpecify options to control how the match operation will be performed. The following option characters are supported:a             anchored mode (only match from the beginning)d             enable the DFA mode (or the longest token match semantics).              this requires PCRE 6.0+ or else a Lua exception will be thrown.              first introduced in ngx_lua v0.3.1rc30.D             enable duplicate named pattern support. This allows named              subpattern names to be repeated, returning the captures in              an array-like Lua table. for example,                local m = ngx.re.match("hello, world",                                       "(?
      
       \w+), (?
       
        \w+)",                                       "D")                -- m["named"] == {"hello", "world"}              this option was first introduced in the v0.7.14 release.              this option requires at least PCRE 8.12.i             case insensitive mode (similar to Perl's /i modifier)j             enable PCRE JIT compilation, this requires PCRE 8.21+ which              must be built with the --enable-jit option. for optimum performance,              this option should always be used together with the 'o' option.              first introduced in ngx_lua v0.3.1rc30.J             enable the PCRE Javascript compatible mode. this option was              first introduced in the v0.7.14 release. this option requires              at least PCRE 8.12.m             multi-line mode (similar to Perl's /m modifier)o             compile-once mode (similar to Perl's /o modifier),              to enable the worker-process-level compiled-regex caches             single-line mode (similar to Perl's /s modifier)u             UTF-8 mode. this requires PCRE to be built with              the --enable-utf8 option or else a Lua exception will be thrown.U             similar to "u" but disables PCRE's UTF-8 validity check on              the subject string. first introduced in ngx_lua v0.8.1.x             extended mode (similar to Perl's /x modifier)