正常的日志目录应该是/var/log/tomcat，而在tomcat7当中日志全都跑到/var/log/messages当中了。
原因及解决方法：
Tomcat when used with official Arch Linux packages uses systemd's journalctl for startup log. This means that files /var/log/tomcat7/catalina.err and /var/log/tomcat7/catalina.out are not used. Other logs such as access logs and business logs defined in /etc/tomcat7/server.xml as Valve will still by default end up in /var/log/tomcat7/.
To restore upstream style logging, copy systemd file /lib/systemd/system/tomcat7.service to /etc/systemd/system/tomcat7.service and change both SYSLOG for the absolute paths of log files.所以将/lib/systemd/system/tomcat.service
copy至/etc/systemd/system/tomcat.service