[Linuxephus™]

thanks bro, i want to learn Unix, but in this time working on CISCO device, hope in future, i can take ur help in learn.

No need for thanks mate.
And if you're working with and/or on Cisco, then you've already begun learning the rudimentaries of Unix/Linux considering Cisco is predominantly built using components of Unix/Linux on the software side (infer embedded) as Cisco has their own Cisco IOS used as the foundation for the majority of their routers etceteral.