How to use RCON on Mac

The server alias syntax is the same as on the client side. You can place aliases inside server.cfg or choose to separate them into their own file for the sake of neatness.

server.cfg

exec aliases.cfg

aliases.cfg

alias "meleeon" "sm_cvar sm_meleemode_enabled 1;sm_cvar example 0"
alias "meleeoff" "sm_cvar sm_meleemode_enabled 0;sm_cvar example 1"

You should also be able to change the default values of cvars registered in SourceMod plugins or have them vary by map. Just ask if that interests you.

What you're looking for is called remote-console, or rcon. It's built right into the game; to use it, set rcon_password to the same value on the server (in server.cfg) and client (in the console), then type into the client-console rcon <command> for any commands you want to run on the server.

You can use rcon outside of the game, too. The most popular tool for this is HLSW.