How do I fix Bowtie and Python Error (Errno2)?

Question

I am trying to repeat the "Indexing a reference genome" step of this tutorial.

However, when I run the command

../bowtie2-master/bowtie2-build ./bowtie2-master/example/reference/lambda_virus.fa lambda_virus

This error happens:

  File "../bowtie2-master/bowtie2-build", line 90, in <module>
    main()
  File "../bowtie2-master/bowtie2-build", line 87, in main
    sys.exit(subprocess.call(list(argv)))
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 172, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 394, in __init__
    errread, errwrite)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 1047, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

Output of pwd:

/Users/ltelles/Desktop/documents_desktop/bioinformatics/bowtie2_example_project

What is going on and how can I fix it? Thank's!