mysql_replication []

        
              show slave status \G

Important to look out for:

        
              Slave_IO_Running: Yes
Slave_SQL_Running: No

The following means that the master and slave are communicating. The master is sending over the IO commands and the slave is receiving them

        
              Slave_IO_Running: Yes

The Slave is NOT running the IO commands sent from the Master

        
              Slave_SQL_Running: No

        
              mysql -e 'show slave status\G'|grep -i behind

        
              mysql -e 'SHOW SLAVE STATUS\G;' | grep -i slave*running