actually i was trying to change some of my environmental variables permanently, but couldn't find a proper solution for that.
set command to see my variables .
HISTSIZE=0 command to change the value to 0 and then used export HISTSIZE
set command to see if its working, yes histsize is zero and if i type history there are no traces and it is not storing as well
open a new terminal used set command to check if its working there, but histsize is having default value of 1000.
Any help is appreciated