What does %s mean in Python? And what does the following bit of code do?
if len(sys.argv) < 2:
sys.exit('Usage: %s database-name' % sys.argv)
if not os.path.exists(sys.argv):
sys.exit('ERROR: Database %s was not found!' % sys.argv)
It is a string formatting syntax (which it borrows from C).
Please see "Formatting Strings":
Python supports formatting values into strings. Although this can include very complicated expressions, the most basic usage is to insert values into a string with the
Edit: Here is a really simple example:
name = raw_input("who are you?") print "hello %s" % (name,)
%s token allows me to insert (and potentially format) a string. Notice that the
%s token is replaced by whatever I pass to the string after the
% symbol. Notice also that I am using a tuple here as well (when you only have one string using a tuple is optional) to illustrate that multiple strings can be inserted and formatted in one statement.