title: I have a error in makefile while running xv6 in ubuntu
body: <p>i have cloned the xv6-public repository in ubuntu virtual box and i have used the commands</p>
  <pre><code>$sudo apt-get install qemu
  $git clone https://github.com/mit-pdos/xv6-public.git
  $cd xv6-public
  $make
  $make qemu-nox
  </code></pre>
  <p>when i run make qemu-nox i am getting error like below</p>
  <pre><code>***
  *** Error: Couldn't find a working QEMU executable.
  *** Is the directory containing the qemu binary in your PATH
  *** or have you tried setting the QEMU variable in Makefile?
  ***
  nographic -drive file=fs.img,index=1,media=disk,format=raw -drive file=xv6.img,index=0,media=disk,format=raw -smp 2 -m 512 
  make: nographic: Command not found
  make: [Makefile:231: qemu-nox] Error 127 (ignored)
  
  </code></pre>
  <p>can anyone give any solution for this</p>