nginx: unrecognized service

[root@host ~]# service nginx status
nginx: unrecognized service
[root@host ~]# service nginx start
nginx: unrecognized service
[root@host ~]# service mysqld start
Starting MariaDB SUCCESS!
[root@host ~]# 180331 18:38:55 mysqld_safe Logging to '/data/mariadb/mysql-error.log'.
180331 18:38:55 mysqld_safe A mysqld process already exists
^C
[root@host ~]# service nginx start
nginx: unrecognized service
[root@host ~]# service php -fpm start
php: unrecognized service
[root@host ~]# service tomcat start
Tomcat is already running (pid: 1397)
[root@host ~]#
不能打开主页，不能打开phpmyadmin