u will find a lot of help in the official forum
here
http://japlus.fragism.com/)
moreover, your question may be already asked in the FAQ or the forum
use the search function in the forum
but /amvstr work like that
amvstr can execute a variable already defined in the server.cfg
for example: put in your server.cfg ==> seta test_vstr " d_saberSPStyleDamage 1 ; jp_alterDMG 0 "
restart your server
then log in as an admin, then type into the console /amvstr test_vstr
=====> it will execute d_saberSPStyleDamage 1 then jp_alterDMG 0
this cmd is ideal to create macro variable that u can use to change quickely dynamically the cvar value
But the previous value keep the same in the server.cfg
so if you restart the server, it will load the previous value of the server.Cfg