Hello,
I already installed python 2.7.Still I'm getting this error.
Nevertheless, you're missing a 'python2' symbolic link to your python2.7 binary in one of your binary-pathes. Not all Linux distributions might follow the convention to provide a python2 symbolic link by default.
You can create such a symbolic link manually. Please, make sure that you can type python2 in your terminal without getting an "No such file or directory" error before trying to build Genode for OKL4 again.
Alternatively, Naveen could work with the genodelabs/master branch of the official Git repository. In April, I introduced a simple mechanism to detect the installed Python2 version automatically. See
https://github.com/genodelabs/genode/commit/de2723c794366695d1871dc23f87794f...
So when working with the Git repository, this issue should be solved by now.
Cheers Norman