update readme

README.md

@@ -72,9 +72,9 @@ Unit [K,M,G,T] means it is bytes. 1T=1024G 1G=1024M 1M=1024K 1K=1024bytes
 
 ## Customize the status sections
 
-Support os status sections: 'time','os_cpu','os_load','os_swap','os_net_bytes','os_net_packages','os_disk','proc_cpu','proc_mem'
+Support os status sections: 'time','os_cpu','os_load','os_swap','os_net_bytes','os_net_packages','os_disk','os_mem','proc_cpu','proc_mem'
 
-Support mysql status sections: 'time','os_cpu','os_load','os_swap','os_net_bytes','os_net_packages','os_disk','proc_cpu','proc_mem','cmds','net','threads_conns','innodb_redo_log','innodb_log','innodb_bp_usage','innodb_rows','innodb_data','row_lock','table_lock','innodb_internal_lock','slave','handler_read','handler_ddl','handler_trx'
+Support mysql status sections: 'time','os_cpu','os_load','os_swap','os_net_bytes','os_net_packages','os_disk','os_mem','proc_cpu','proc_mem','cmds','net','threads_conns','innodb_redo_log','innodb_log','innodb_bp_usage','innodb_rows','innodb_data','row_lock','table_lock','innodb_internal_lock','slave','handler_read','handler_ddl','handler_trx'
 
 
 ### You can use -I option to show the sections instructions, the follow is the mysql sections:
@@ -142,6 +142,13 @@ Support mysql status sections: 'time','os_cpu','os_load','os_swap','os_net_bytes
            | read/write.
     Column |%util : Disk utilization percent.
     ________________________________________
+    Section|os_mem : os memory status, collect from /proc/meminfo file
+    ----------------------------------------
+    Column |total : Total memory size bytes.
+    Column |free : Free memory size bytes.
+    Column |buffer : Buffered memory size bytes.
+    Column |cached : Cached memory size bytes.
+    ________________________________________
     Section|proc_cpu : process cpu status, collect from /proc/[pid]/stat
            | file, usually the pid should automatically get from the
            | server.getPidNum() function, but you can also replace the