path for echo binary location I am unable to find the "echo" binary in the /bin path (supposedly the path for storage of essential binaries) on Galaxy S2 on which I am working on. And yes, the "echo" command is perfectly working when I tried it on adb shell. I have also tried looking into sbin, xbin and other such directories. 
Does somebody know where else I can find it?
Yepp, in the shell. echo is a built-in command, see Why is echo a shell built in command?, Wikipedia: Shell built-in, and The echo command. So you won't find any "echo binary", as it is contained in the sh command.