Python - generate case insensitive REGEXP like string

How can I autogenerate a case insensitive REGEXP for a string that may have the case following variations: 'ENTI', 'Enti'

I got this so far but it looks clumsy,

entity_type = 'Enti'
prefix = 'E'
for char in entity_type[1:]:                          
    logs_prefix += '[' + char.upper() + char.lower() + ']'
print logs_prefix

>>>'E[Nn][Tt][Yy]'

My goal is to initially discover the list of active logs (the rotated ones will be ending with a timestamp) which start with a given case insensitive sequence, so I can

regexp_filters = logs_prefix + '_A.out'
command = "ssh %(user)s@%(ip)s 'cd %(source_path)s; ls -t %(regexp_filters)s'" % locals()

and generate different rsync expressions for a range of hosts. Ignore the exclude, its made of several --excludes witholder,开发者_Go百科 crashed '*_A.out' logs

sync = "rsync -e ssh -a %(remote_rsync_binary)s --compress=9 -pgtov %(excluded_expression)s %(filters_expression)s --exclude='*' %s(user)@%(ip)s:%(source_path)s%(file_filter)s %(target_path)s" % locals()

Minor question, how to easily enclose a string/char with other chars, in this case: [char]

EDIT : Found a cleaner solution, is there a better way?

for char in entity_type[1:]:
    prefix += "[%s]" % "%s%s" % (char.upper(), char.lower() ) 

EDIT2: (improvement) as @eyquem wrote,

prefix + ''.join( "[%s%s]" % (char.upper(), char.lower() for char in entity_type[1:])

Try this:

reEnti = re.compile('ent[iy]',re.IGNORECASE)

You could try this (Python 2.7.1):

>>> def goofy_regexp(s):
      return '{}|{}'.format(s.upper(), s.title())

>>> goofy_regexp('enti')
'ENTI|Enti'

Here's a 2.6 version with old style string formatting:

>>> def goofy_regexp26(s):
    return '%s|%s' % (s.upper(), s.title())

>>> goofy_regexp26('enti')
'ENTI|Enti'

I can't believe python doesn't actually support ignorecase in a regex. Just passing "Ignorecase" as a flag to the regex parser is no better than doing upper() after the fact and is useless for defining a case-insenstive regex