IndentationError: expected an indented block but it's there

[Peter Otten]

JackM wrote:

> Having a problem getting a py script to execute. Got this error:
> 
> File "/scripts/blockIPv4.py", line 19
>      ip = line.split(';')[0]
>       ^
> IndentationError: expected an indented block
> 
> 
> I'm perplexed because the code that the error refers to *is* indented:
> 
> 
> 
> with open('/var/www/html/mydomain.com/banlist.txt','r') as inFile:
>      for line in inFile.readlines():
>          ip = line.split(';')[0]
>          output = os.popen( '/etc/sysconfig/iptables -A INPUT -s ' + ip
> + ' -j REJECT' )
>          logFile.write(ip+' - Has been blocked\n')
> 
> 
> What am I missing here?

If you are mixing tabs and spaces to indent your code and have your editor 
configured with a tab width other than eight your code may look correct when 
it isn't. A simulation in the interactive interpreter:

The actual file contents:

>>> s = "if 1:\n\tif 2:\n    \tprint 'hi'"

What you see:

>>> print s.expandtabs(4)
if 1:
    if 2:
        print 'hi'
>>> exec s.expandtabs(4)
hi

What Python "sees":

>>> print s.expandtabs(8)
if 1:
        if 2:
        print 'hi'
>>> exec s
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 3
    print 'hi'
        ^
IndentationError: expected an indented block

Solution: configure your editor to use four spaces for indentation.