package main
import (
"regexp"
"fmt"
)
func main() {
var re = regexp.MustCompile(`(?m)^(wsrep_provider_options(?!.*\bgcache.size\b).*)('$)`)
var str = `wsrep_provider_options='gmcast.segment=0; ist.recv_addr=tcp://db7; ist.recv_bind=tcp://0.0.0.0; socket.ssl_cert=/etc/mysql/wsrep/ssl/gmnode.pem; socket.ssl_key=/etc/mysql/wsrep/ssl/gmnode.key; socket.ssl_ca=/etc/mysql/wsrep/ssl/gmca.pem'
wsrep_provider_options='gmcast.segment=0; ist.recv_addr=tcp://db7; ist.recv_bind=tcp://0.0.0.0; socket.ssl_cert=/etc/mysql/wsrep/ssl/gmnode.pem; socket.ssl_key=/etc/mysql/wsrep/ssl/gmnode.key; socket.ssl_ca=/etc/mysql/wsrep/ssl/gmca.pem; gcache.size=4G'
wsrep_provider_options='gcache.size=4G; gmcast.segment=0; ist.recv_addr=tcp://db7; ist.recv_bind=tcp://0.0.0.0; socket.ssl_cert=/etc/mysql/wsrep/ssl/gmnode.pem; socket.ssl_key=/etc/mysql/wsrep/ssl/gmnode.key; socket.ssl_ca=/etc/mysql/wsrep/ssl/gmca.pem'`
var substitution = "\1; gcache.size=4G\2"
fmt.Println(re.ReplaceAllString(str, substitution))
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/