Linux - Allow SSH access to Linux Server for new user account

To allow SSH access to create user

AllowUsers user1 user2

This directive is opposite of DenyUsers directive.

AllowGroups group1 group2

This directive is opposite of DenyGroups directive.

You should always block access to root user/group:

Open /etc/ssh/sshd_config file:

# vi /etc/ssh/sshd_config

Make sure at least one user is allowed to use 'su -' command.

Save the file and restart the sshd service.

Linux - to start a LINUX program/services whenever the system boots

To make Service1 start whenever the system boots, enter:

# chkconfig --level 3 <service1> on







Mysql - to check respective MySQL table size in the specific database

SELECT table_name,

       concat(round(sum(table_rows)/1000000,2),'M') rows,

       concat(round(sum(data_length)/(1024*1024*1024),2),'G') data,

       concat(round(sum(index_length)/(1024*1024*1024),2),'G') idx,

       concat(round(sum(data_length+index_length)/(1024*1024*1024),2),'G') total_size,

       round(sum(index_length)/sum(data_length),2) idxfrac

       FROM information_schema.TABLES

WHERE table_schema = "<specific_database_name>"

group by table_name;

NOTES:

<specific_database_name> - replace this with your database name

MySQL - to check dabatase size

 SELECT table_schema "Data Base Name", sum( data_length + index_length ) / 1024 / 1024 "Data Base Size in MB", sum( data_free )/ 1024 / 1024 "Free Space in MB" FROM information_schema.TABLES WHERE table_schema = '<DATABASE NAME>' GROUP BY table_schema ;