def uname_func():

    uname = "uname"
    uname_arg = "-a"
    print ("Gathering system information with %s command:\n") % uname
    subprocess.call([uname, uname_arg])

name = 2
print('name=', %s) %name
SyntaxError: invalid syntax
>>> print('name=',%s) %name
  File "<stdin>", line 1
    print('name=',%s) %name

Python 3.1.2 (r312:79147, Sep 27 2010, 09:45:41) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> uname = "uname"
>>> uname_arg = "-a"
>>> print ("Gathering system information with %s command:\n") % uname
Gathering system information with %s command:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for %: 'NoneType' and 'str'

var = ("Gathering system information with %s command:\n") % uname
print var

print("Gathering system information with {0} command:\n".format(uname))