diff --git a/src/yunohost/app.py b/src/yunohost/app.py
index 582f8e065..8fcfa0caa 100644
--- a/src/yunohost/app.py
+++ b/src/yunohost/app.py
@@ -24,13 +24,13 @@
     Manage apps
 """
 import os
-import sys
 import json
 import shutil
-import stat
 import yaml
 import time
 import re
+import string
+import random
 import socket
 import urlparse
 import errno
@@ -42,6 +42,10 @@ from moulinette.utils.log import getActionLogger
 
 from yunohost.service import service_log
 from yunohost.utils import packages
+from yunohost.hook import hook_add, hook_remove, hook_exec, hook_callback
+from yunohost.user import user_list, user_info
+from yunohost.domain import domain_list
+
 
 logger = getActionLogger('yunohost.app')
 
@@ -333,8 +337,6 @@ def app_upgrade(auth, app=[], url=None, file=None):
         url -- Git url to fetch for upgrade
 
     """
-    from yunohost.hook import hook_add, hook_remove, hook_exec
-
     try:
         app_list()
     except MoulinetteError:
@@ -445,8 +447,6 @@ def app_install(auth, app, label=None, args=None):
         args -- Serialize arguments for app installation
 
     """
-    from yunohost.hook import hook_add, hook_remove, hook_exec
-
     # Fetch or extract sources
     try: os.listdir(install_tmp)
     except OSError: os.makedirs(install_tmp)
@@ -588,8 +588,6 @@ def app_remove(auth, app):
         app -- App(s) to delete
 
     """
-    from yunohost.hook import hook_exec, hook_remove
-
     if not _is_installed(app):
         raise MoulinetteError(errno.EINVAL,
                               m18n.n('app_not_installed', app=app))
@@ -631,9 +629,6 @@ def app_addaccess(auth, apps, users=[]):
         apps
 
     """
-    from yunohost.user import user_list, user_info
-    from yunohost.hook import hook_callback
-
     result = {}
 
     if not users:
@@ -686,9 +681,6 @@ def app_removeaccess(auth, apps, users=[]):
         apps
 
     """
-    from yunohost.user import user_list
-    from yunohost.hook import hook_callback
-
     result = {}
 
     remove_all = False
@@ -736,8 +728,6 @@ def app_clearaccess(auth, apps):
         apps
 
     """
-    from yunohost.hook import hook_callback
-
     if not isinstance(apps, list): apps = [apps]
 
     for app in apps:
@@ -788,8 +778,6 @@ def app_makedefault(auth, app, domain=None):
         domain
 
     """
-    from yunohost.domain import domain_list
-
     app_settings = _get_app_settings(app)
     app_domain = app_settings['domain']
     app_path   = app_settings['path']
@@ -881,8 +869,6 @@ def app_checkurl(auth, url, app=None):
         app -- Write domain & path to app settings for further checks
 
     """
-    from yunohost.domain import domain_list
-
     if "https://" == url[:8]:
         url = url[8:]
     elif "http://" == url[:7]:
@@ -965,9 +951,6 @@ def app_ssowatconf(auth):
 
 
     """
-    from yunohost.domain import domain_list
-    from yunohost.user import user_list
-
     with open('/etc/yunohost/current_host', 'r') as f:
         main_domain = f.readline().rstrip()
 
@@ -1404,11 +1387,11 @@ def _value_for_locale(values):
     if not isinstance(values, dict):
         return values
 
-    for lang in [m18n.locale, m18n.default_locale]:
-        try:
-            return _encode_string(values[lang])
-        except KeyError:
-            continue
+    if m18n.locale in values:
+        return _encode_string(values[m18n.locale])
+
+    if m18n.default_locale in values:
+        return _encode_string(values[m18n.default_locale])
 
     # Fallback to first value
     return _encode_string(values.values()[0])
@@ -1466,6 +1449,7 @@ def _check_manifest_requirements(manifest):
                                      pkgname=pkgname, version=version,
                                      spec=spec))
 
+
 def _parse_args_from_manifest(manifest, action, args={}, auth=None):
     """Parse arguments needed for an action from the manifest
 
@@ -1480,9 +1464,6 @@ def _parse_args_from_manifest(manifest, action, args={}, auth=None):
         args -- A dictionnary of arguments to parse
 
     """
-    from yunohost.domain import domain_list
-    from yunohost.user import user_info
-
     args_list = OrderedDict()
     try:
         action_args = manifest['arguments'][action]
@@ -1577,6 +1558,7 @@ def _parse_args_from_manifest(manifest, action, args={}, auth=None):
             args_list[arg_name] = arg_value
     return args_list
 
+
 def _make_environment_dict(args_dict):
     """
     Convert a dictionnary containing manifest arguments
@@ -1591,6 +1573,7 @@ def _make_environment_dict(args_dict):
         env_dict[ "YNH_APP_ARG_%s" % arg_name.upper() ] = arg_value
     return env_dict
 
+
 def _parse_app_instance_name(app_instance_name):
     """
     Parse a Yunohost app instance name and extracts the original appid
@@ -1618,6 +1601,7 @@ def _parse_app_instance_name(app_instance_name):
     app_instance_nb = int(match.groupdict().get('appinstancenb')) if match.groupdict().get('appinstancenb') is not None else 1
     return (appid, app_instance_nb)
 
+
 def is_true(arg):
     """
     Convert a string into a boolean
@@ -1650,7 +1634,5 @@ def random_password(length=8):
         length -- The string length to generate
 
     """
-    import string, random
-
     char_set = string.ascii_uppercase + string.digits + string.ascii_lowercase
     return ''.join(random.sample(char_set, length))
diff --git a/src/yunohost/backup.py b/src/yunohost/backup.py
index 649f3116e..f037941f6 100644
--- a/src/yunohost/backup.py
+++ b/src/yunohost/backup.py
@@ -25,7 +25,6 @@
 """
 import os
 import re
-import sys
 import json
 import errno
 import time
diff --git a/src/yunohost/domain.py b/src/yunohost/domain.py
index b41891fb9..b5aee0150 100644
--- a/src/yunohost/domain.py
+++ b/src/yunohost/domain.py
@@ -2,7 +2,7 @@
 
 """ License
 
-    Copyright (C) 2013 YunoHost
+    Copyright (C) 2013-2016 YunoHost
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU Affero General Public License as published
@@ -24,20 +24,20 @@
     Manage domains
 """
 import os
-import sys
-import datetime
 import re
-import shutil
 import json
 import yaml
 import errno
+import shutil
 import requests
-from urllib import urlopen
 
 from moulinette.core import MoulinetteError
 from moulinette.utils.log import getActionLogger
 
 from yunohost.service import service_regen_conf
+from yunohost.hook import hook_callback
+from yunohost.dyndns import dyndns_subscribe
+from yunohost.app import app_ssowatconf
 
 logger = getActionLogger('yunohost.domain')
 
@@ -80,13 +80,9 @@ def domain_add(auth, domain, dyndns=False):
         dyndns -- Subscribe to DynDNS
 
     """
-    from yunohost.hook import hook_callback
 
     attr_dict = { 'objectClass' : ['mailDomain', 'top'] }
 
-    now = datetime.datetime.now()
-    timestamp = str(now.year) + str(now.month) + str(now.day)
-
     if domain in domain_list(auth)['domains']:
         raise MoulinetteError(errno.EEXIST, m18n.n('domain_exists'))
 
@@ -94,7 +90,6 @@ def domain_add(auth, domain, dyndns=False):
     if dyndns:
         if len(domain.split('.')) < 3:
             raise MoulinetteError(errno.EINVAL, m18n.n('domain_dyndns_invalid'))
-        from yunohost.dyndns import dyndns_subscribe
 
         try:
             r = requests.get('https://dyndns.yunohost.org/domains')
@@ -160,12 +155,14 @@ def domain_add(auth, domain, dyndns=False):
             with open('/etc/yunohost/installed', 'r') as f:
                 service_regen_conf(names=[
                     'nginx', 'metronome', 'dnsmasq', 'rmilter'])
-                os.system('yunohost app ssowatconf > /dev/null 2>&1')
+                app_ssowatconf(auth)
         except IOError: pass
     except:
         # Force domain removal silently
-        try: domain_remove(auth, domain, True)
-        except: pass
+        try:
+            domain_remove(auth, domain, True)
+        except:
+            pass
         raise
 
     hook_callback('post_domain_add', args=[domain])
@@ -182,8 +179,6 @@ def domain_remove(auth, domain, force=False):
         force -- Force the domain removal
 
     """
-    from yunohost.hook import hook_callback
-
     if not force and domain not in domain_list(auth)['domains']:
         raise MoulinetteError(errno.EINVAL, m18n.n('domain_unknown'))
 
@@ -200,12 +195,12 @@ def domain_remove(auth, domain, force=False):
                                           m18n.n('domain_uninstall_app_first'))
 
     if auth.remove('virtualdomain=' + domain + ',ou=domains') or force:
-        os.system('rm -rf /etc/yunohost/certs/%s' % domain)
+        shutil.rmtree('/etc/yunohost/certs/%s' % domain)
     else:
         raise MoulinetteError(errno.EIO, m18n.n('domain_deletion_failed'))
 
     service_regen_conf(names=['nginx', 'metronome', 'dnsmasq'])
-    os.system('yunohost app ssowatconf > /dev/null 2>&1')
+    app_ssowatconf(auth)
 
     hook_callback('post_domain_remove', args=[domain])
 
@@ -296,7 +291,7 @@ def get_public_ip(protocol=4):
     else:
         raise ValueError("invalid protocol version")
     try:
-        return urlopen(url).read().strip()
+        return requests.get(url).content.strip()
     except IOError:
         logger.debug('cannot retrieve public IPv%d' % protocol, exc_info=1)
         raise MoulinetteError(errno.ENETUNREACH,
diff --git a/src/yunohost/dyndns.py b/src/yunohost/dyndns.py
index 878bc577e..55f7fd45b 100644
--- a/src/yunohost/dyndns.py
+++ b/src/yunohost/dyndns.py
@@ -40,6 +40,10 @@ from yunohost.domain import get_public_ip
 logger = getActionLogger('yunohost.dyndns')
 
 
+RE_DYNDNS_PRIVATE_KEY = re.compile(
+    r'.*/K(?P<domain>[^\s\+]+)\.\+157.+\.private$'
+)
+
 class IPRouteLine(object):
     """ Utility class to parse an ip route output line
 
@@ -62,10 +66,6 @@ class IPRouteLine(object):
         for k, v in self.m.groupdict().items():
             setattr(self, k, v)
 
-re_dyndns_private_key = re.compile(
-    r'.*/K(?P<domain>[^\s\+]+)\.\+157.+\.private$'
-)
-
 
 def dyndns_subscribe(subscribe_host="dyndns.yunohost.org", domain=None, key=None):
     """
@@ -171,7 +171,7 @@ def dyndns_update(dyn_host="dyndns.yunohost.org", domain=None, key=None,
         if domain is None:
             # Retrieve the first registered domain
             for path in glob.iglob('/etc/yunohost/dyndns/K*.private'):
-                match = re_dyndns_private_key.match(path)
+                match = RE_DYNDNS_PRIVATE_KEY.match(path)
                 if not match:
                     continue
                 _domain = match.group('domain')
diff --git a/src/yunohost/firewall.py b/src/yunohost/firewall.py
index ef6249434..f304deb00 100644
--- a/src/yunohost/firewall.py
+++ b/src/yunohost/firewall.py
@@ -36,7 +36,9 @@ except ImportError:
 from moulinette.core import MoulinetteError
 from moulinette.utils import process
 from moulinette.utils.log import getActionLogger
-from moulinette.utils.text import prependlines
+from moulinette.utils.text import prependlines, searchf
+
+from yunohost.hook import hook_callback
 
 firewall_file = '/etc/yunohost/firewall.yml'
 upnp_cron_job = '/etc/cron.d/yunohost-firewall-upnp'
@@ -123,7 +125,7 @@ def firewall_disallow(protocol, port, ipv4_only=False, ipv6_only=False,
     ipvs = ['ipv4', 'ipv6']
     upnp = True
     if ipv4_only and ipv6_only:
-        upnp = True # automatically disallow UPnP
+        upnp = True  # automatically disallow UPnP
     elif ipv4_only:
         ipvs = ['ipv4',]
         upnp = upnp_only
@@ -178,7 +180,7 @@ def firewall_list(raw=False, by_ip_version=False, list_forwarded=False):
         ports = sorted(set(ports['ipv4']) | set(ports['ipv6']))
 
     # Format returned dict
-    ret = { "opened_ports": ports }
+    ret = {"opened_ports": ports}
     if list_forwarded:
         # Combine TCP and UDP forwarded ports
         ret['forwarded_ports'] = sorted(
@@ -194,8 +196,6 @@ def firewall_reload(skip_upnp=False):
         skip_upnp -- Do not refresh port forwarding using UPnP
 
     """
-    from yunohost.hook import hook_callback
-
     reloaded = False
     errors = False
 
@@ -224,8 +224,8 @@ def firewall_reload(skip_upnp=False):
         # Iterate over ports and add rule
         for protocol in ['TCP', 'UDP']:
             for port in firewall['ipv4'][protocol]:
-                rules.append("iptables -A INPUT -p %s --dport %s -j ACCEPT" \
-                                 % (protocol, process.quote(str(port))))
+                rules.append("iptables -A INPUT -p %s --dport %s -j ACCEPT"
+                             % (protocol, process.quote(str(port))))
         rules += [
             "iptables -A INPUT -i lo -j ACCEPT",
             "iptables -A INPUT -p icmp -j ACCEPT",
@@ -253,8 +253,8 @@ def firewall_reload(skip_upnp=False):
         # Iterate over ports and add rule
         for protocol in ['TCP', 'UDP']:
             for port in firewall['ipv6'][protocol]:
-                rules.append("ip6tables -A INPUT -p %s --dport %s -j ACCEPT" \
-                                 % (protocol, process.quote(str(port))))
+                rules.append("ip6tables -A INPUT -p %s --dport %s -j ACCEPT"
+                             % (protocol, process.quote(str(port))))
         rules += [
             "ip6tables -A INPUT -i lo -j ACCEPT",
             "ip6tables -A INPUT -p icmpv6 -j ACCEPT",
@@ -308,13 +308,14 @@ def firewall_upnp(action='status', no_refresh=False):
         try:
             # Remove old cron job
             os.remove('/etc/cron.d/yunohost-firewall')
-        except: pass
+        except:
+            pass
         action = 'status'
         no_refresh = False
 
     if action == 'status' and no_refresh:
         # Only return current state
-        return { 'enabled': enabled }
+        return {'enabled': enabled}
     elif action == 'enable' or (enabled and action == 'status'):
         # Add cron job
         with open(upnp_cron_job, 'w+') as f:
@@ -330,7 +331,8 @@ def firewall_upnp(action='status', no_refresh=False):
         try:
             # Remove cron job
             os.remove(upnp_cron_job)
-        except: pass
+        except:
+            pass
         enabled = False
         if action == 'status':
             no_refresh = True
@@ -364,7 +366,8 @@ def firewall_upnp(action='status', no_refresh=False):
                         if upnpc.getspecificportmapping(port, protocol):
                             try:
                                 upnpc.deleteportmapping(port, protocol)
-                            except: pass
+                            except:
+                                pass
                         if not enabled:
                             continue
                         try:
@@ -403,7 +406,7 @@ def firewall_upnp(action='status', no_refresh=False):
 
     if action == 'enable' and not enabled:
         raise MoulinetteError(errno.ENXIO, m18n.n('upnp_port_open_failed'))
-    return { 'enabled': enabled }
+    return {'enabled': enabled}
 
 
 def firewall_stop():
@@ -434,7 +437,6 @@ def _get_ssh_port(default=22):
     Retrieve the SSH port from the sshd_config file or used the default
     one if it's not defined.
     """
-    from moulinette.utils.text import searchf
     try:
         m = searchf(r'^Port[ \t]+([0-9]+)$',
                     '/etc/ssh/sshd_config', count=-1)
@@ -444,12 +446,14 @@ def _get_ssh_port(default=22):
         pass
     return default
 
+
 def _update_firewall_file(rules):
     """Make a backup and write new rules to firewall file"""
     os.system("cp {0} {0}.old".format(firewall_file))
     with open(firewall_file, 'w') as f:
         yaml.safe_dump(rules, f, default_flow_style=False)
 
+
 def _on_rule_command_error(returncode, cmd, output):
     """Callback for rules commands error"""
     # Log error and continue commands execution
diff --git a/src/yunohost/hook.py b/src/yunohost/hook.py
index aafe15459..0bf015320 100644
--- a/src/yunohost/hook.py
+++ b/src/yunohost/hook.py
@@ -24,15 +24,12 @@
     Manage hooks
 """
 import os
-import sys
-import re
-import json
 import errno
-import subprocess
 from glob import iglob
 
 from moulinette.core import MoulinetteError
 from moulinette.utils import log
+from moulinette.utils.process import call_async_output
 
 hook_folder = '/usr/share/yunohost/hooks/'
 custom_hook_folder = '/etc/yunohost/hooks.d/'
@@ -52,14 +49,16 @@ def hook_add(app, file):
     path, filename = os.path.split(file)
     priority, action = _extract_filename_parts(filename)
 
-    try: os.listdir(custom_hook_folder + action)
-    except OSError: os.makedirs(custom_hook_folder + action)
+    try:
+        os.listdir(custom_hook_folder + action)
+    except OSError:
+        os.makedirs(custom_hook_folder + action)
 
-    finalpath = custom_hook_folder + action +'/'+ priority +'-'+ app
+    finalpath = custom_hook_folder + action + '/' + priority + '-' + app
     os.system('cp %s %s' % (file, finalpath))
     os.system('chown -hR admin: %s' % hook_folder)
 
-    return { 'hook': finalpath }
+    return {'hook': finalpath}
 
 
 def hook_remove(app):
@@ -74,8 +73,9 @@ def hook_remove(app):
         for action in os.listdir(custom_hook_folder):
             for script in os.listdir(custom_hook_folder + action):
                 if script.endswith(app):
-                    os.remove(custom_hook_folder + action +'/'+ script)
-    except OSError: pass
+                    os.remove(custom_hook_folder + action + '/' + script)
+    except OSError:
+        pass
 
 
 def hook_info(action, name):
@@ -136,11 +136,11 @@ def hook_list(action, list_by='name', show_info=False):
             def _append_hook(d, priority, name, path):
                 # Use the priority as key and a dict of hooks names
                 # with their info as value
-                value = { 'path': path }
+                value = {'path': path}
                 try:
                     d[priority][name] = value
                 except KeyError:
-                    d[priority] = { name: value }
+                    d[priority] = {name: value}
         else:
             def _append_hook(d, priority, name, path):
                 # Use the priority as key and the name as value
@@ -162,11 +162,12 @@ def hook_list(action, list_by='name', show_info=False):
                         if h['path'] != path:
                             h['path'] = path
                         return
-                l.append({ 'priority': priority, 'path': path })
+                l.append({'priority': priority, 'path': path})
                 d[name] = l
         else:
             if list_by == 'name':
                 result = set()
+
             def _append_hook(d, priority, name, path):
                 # Add only the name
                 d.add(name)
@@ -204,7 +205,7 @@ def hook_list(action, list_by='name', show_info=False):
         logger.debug("custom hook folder not found for action '%s' in %s",
                      action, custom_hook_folder)
 
-    return { 'hooks': result }
+    return {'hooks': result}
 
 
 def hook_callback(action, hooks=[], args=None, no_trace=False, chdir=None,
@@ -226,7 +227,7 @@ def hook_callback(action, hooks=[], args=None, no_trace=False, chdir=None,
             (name, priority, path, succeed) as arguments
 
     """
-    result = { 'succeed': {}, 'failed': {} }
+    result = {'succeed': {}, 'failed': {}}
     hooks_dict = {}
 
     # Retrieve hooks
@@ -258,7 +259,7 @@ def hook_callback(action, hooks=[], args=None, no_trace=False, chdir=None,
             for h in hl:
                 # Update hooks dict
                 d = hooks_dict.get(h['priority'], dict())
-                d.update({ n: { 'path': h['path'] }})
+                d.update({n: {'path': h['path']}})
                 hooks_dict[h['priority']] = d
     if not hooks_dict:
         return result
@@ -308,9 +309,6 @@ def hook_exec(path, args=None, raise_on_error=False, no_trace=False,
         env -- Dictionnary of environment variables to export
 
     """
-    from moulinette.utils.process import call_async_output
-    from yunohost.app import _value_for_locale
-
     # Validate hook path
     if path[0] != '/':
         path = os.path.realpath(path)
diff --git a/src/yunohost/monitor.py b/src/yunohost/monitor.py
index 5142c8305..1ff69b9b2 100644
--- a/src/yunohost/monitor.py
+++ b/src/yunohost/monitor.py
@@ -35,12 +35,15 @@ import errno
 import os
 import dns.resolver
 import cPickle as pickle
-from datetime import datetime, timedelta
+from datetime import datetime
 
 from moulinette.core import MoulinetteError
 from moulinette.utils.log import getActionLogger
 
 from yunohost.domain import get_public_ip
+from yunohost.service import (service_status, service_enable,
+    service_start, service_disable, service_stop)
+
 
 logger = getActionLogger('yunohost.monitor')
 
@@ -406,9 +409,6 @@ def monitor_enable(no_stats=False):
         no_stats -- Disable monitoring statistics
 
     """
-    from yunohost.service import (service_status, service_enable,
-        service_start)
-
     glances = service_status('glances')
     if glances['status'] != 'running':
         service_start('glances')
@@ -433,9 +433,6 @@ def monitor_disable():
     Disable server monitoring
 
     """
-    from yunohost.service import (service_status, service_disable,
-        service_stop)
-
     glances = service_status('glances')
     if glances['status'] != 'inactive':
         service_stop('glances')
@@ -467,8 +464,6 @@ def _get_glances_api():
     else:
         return p
 
-    from yunohost.service import service_status
-
     if service_status('glances')['status'] != 'running':
         raise MoulinetteError(errno.EPERM, m18n.n('monitor_not_enabled'))
     raise MoulinetteError(errno.EIO, m18n.n('monitor_glances_con_failed'))
@@ -722,22 +717,26 @@ def _append_to_stats(stats, monitor, statics=[]):
         statics = [statics]
 
     # Appending function
-    def _append(s, m, st):
-        for k, v in m.items():
-            if k in st:
-                s[k] = v
-            elif isinstance(v, dict):
-                if k not in s:
-                    s[k] = {}
-                s[k] = _append(s[k], v, st)
+    def _append(_stats, _monitor, _statics):
+        for key, value in _monitor.items():
+            if key in _statics:
+                _stats[key] = value
+
+            elif isinstance(value, dict):
+                if key not in _stats:
+                    _stats[key] = {}
+                _stats[key] = _append(_stats[key], value, _statics)
+
             else:
-                if k not in s:
-                    s[k] = []
-                if isinstance(v, list):
-                    s[k].extend(v)
+                if key not in _stats:
+                    _stats[key] = []
+
+                if isinstance(value, list):
+                    _stats[key].extend(value)
                 else:
-                    s[k].append(v)
-        return s
+                    _stats[key].append(value)
+
+        return _stats
 
     stats = _append(stats, monitor, statics)
     return stats
diff --git a/src/yunohost/service.py b/src/yunohost/service.py
index ab26dd2bc..b1b776326 100644
--- a/src/yunohost/service.py
+++ b/src/yunohost/service.py
@@ -36,7 +36,7 @@ from difflib import unified_diff
 from moulinette.core import MoulinetteError
 from moulinette.utils import log, filesystem
 
-from yunohost.hook import hook_list, hook_callback
+from yunohost.hook import hook_callback
 
 
 base_conf_path = '/home/yunohost.conf'
diff --git a/src/yunohost/tools.py b/src/yunohost/tools.py
index f78e32363..e56196760 100644
--- a/src/yunohost/tools.py
+++ b/src/yunohost/tools.py
@@ -24,10 +24,7 @@
     Specific tools
 """
 import os
-import sys
 import yaml
-import re
-import getpass
 import requests
 import json
 import errno
@@ -42,12 +39,12 @@ from moulinette.utils.log import getActionLogger
 from yunohost.app import app_fetchlist, app_info, app_upgrade, app_ssowatconf, app_list
 from yunohost.domain import domain_add, domain_list, get_public_ip
 from yunohost.dyndns import dyndns_subscribe
-from yunohost.firewall import firewall_upnp, firewall_reload
+from yunohost.firewall import firewall_upnp
 from yunohost.service import service_status, service_regen_conf, service_log
-from yunohost.monitor import monitor_disk, monitor_network, monitor_system
+from yunohost.monitor import monitor_disk, monitor_system
 from yunohost.utils.packages import ynh_packages_version
 
-apps_setting_path= '/etc/yunohost/apps/'
+apps_setting_path = '/etc/yunohost/apps/'
 
 logger = getActionLogger('yunohost.tools')
 
@@ -62,12 +59,16 @@ def tools_ldapinit(auth):
         ldap_map = yaml.load(f)
 
     for rdn, attr_dict in ldap_map['parents'].items():
-        try: auth.add(rdn, attr_dict)
-        except: pass
+        try:
+            auth.add(rdn, attr_dict)
+        except:
+            pass
 
     for rdn, attr_dict in ldap_map['children'].items():
-        try: auth.add(rdn, attr_dict)
-        except: pass
+        try:
+            auth.add(rdn, attr_dict)
+        except:
+            pass
 
     admin_dict = {
         'cn': 'admin',
@@ -118,7 +119,7 @@ def tools_maindomain(auth, old_domain=None, new_domain=None, dyndns=False):
             old_domain = f.readline().rstrip()
 
         if not new_domain:
-            return { 'current_main_domain': old_domain }
+            return {'current_main_domain': old_domain}
 
     if not new_domain:
         raise MoulinetteError(errno.EINVAL, m18n.n('new_domain_required'))
@@ -130,7 +131,7 @@ def tools_maindomain(auth, old_domain=None, new_domain=None, dyndns=False):
 
     command_list = [
         'ln -s /etc/yunohost/certs/%s/key.pem /etc/ssl/private/yunohost_key.pem' % new_domain,
-        'ln -s /etc/yunohost/certs/%s/crt.pem /etc/ssl/certs/yunohost_crt.pem'   % new_domain,
+        'ln -s /etc/yunohost/certs/%s/crt.pem /etc/ssl/certs/yunohost_crt.pem' % new_domain,
         'echo %s > /etc/yunohost/current_host' % new_domain,
     ]
 
@@ -146,14 +147,15 @@ def tools_maindomain(auth, old_domain=None, new_domain=None, dyndns=False):
             pass
         else:
             dyndomains = json.loads(r.text)
-            dyndomain  = '.'.join(new_domain.split('.')[1:])
+            dyndomain = '.'.join(new_domain.split('.')[1:])
             if dyndomain in dyndomains:
                 dyndns_subscribe(domain=new_domain)
 
     try:
         with open('/etc/yunohost/installed', 'r') as f:
             service_regen_conf()
-    except IOError: pass
+    except IOError:
+        pass
 
     logger.success(m18n.n('maindomain_changed'))
 
@@ -181,7 +183,7 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
             pass
         else:
             dyndomains = json.loads(r.text)
-            dyndomain  = '.'.join(domain.split('.')[1:])
+            dyndomain = '.'.join(domain.split('.')[1:])
             if dyndomain in dyndomains:
                 if requests.get('https://dyndns.yunohost.org/test/%s' % domain).status_code == 200:
                     dyndns = True
@@ -195,7 +197,7 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
     auth = init_authenticator(('ldap', 'default'),
                               {'uri': "ldap://localhost:389",
                                'base_dn': "dc=yunohost,dc=org",
-                               'user_rdn': "cn=admin" })
+                               'user_rdn': "cn=admin"})
     auth.authenticate('yunohost')
 
     # Initialize LDAP for YunoHost
@@ -212,8 +214,10 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
     ]
 
     for folder in folders_to_create:
-        try: os.listdir(folder)
-        except OSError: os.makedirs(folder)
+        try:
+            os.listdir(folder)
+        except OSError:
+            os.makedirs(folder)
 
     # Change folders permissions
     os.system('chmod 755 /home/yunohost.app')
@@ -232,7 +236,7 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
     if 'redirected_urls' not in ssowat_conf:
         ssowat_conf['redirected_urls'] = {}
 
-    ssowat_conf['redirected_urls']['/'] = domain +'/yunohost/admin'
+    ssowat_conf['redirected_urls']['/'] = domain + '/yunohost/admin'
 
     with open('/etc/ssowat/conf.json.persistent', 'w+') as f:
         json.dump(ssowat_conf, f, sort_keys=True, indent=4)
@@ -244,8 +248,8 @@ def tools_postinstall(domain, password, ignore_dyndns=False):
     ssl_dir = '/usr/share/yunohost/yunohost-config/ssl/yunoCA'
     command_list = [
         'echo "01" > %s/serial' % ssl_dir,
-        'rm %s/index.txt'       % ssl_dir,
-        'touch %s/index.txt'    % ssl_dir,
+        'rm %s/index.txt' % ssl_dir,
+        'touch %s/index.txt' % ssl_dir,
         'cp %s/openssl.cnf %s/openssl.ca.cnf' % (ssl_dir, ssl_dir),
         'sed -i "s/yunohost.org/%s/g" %s/openssl.ca.cnf ' % (domain, ssl_dir),
         'openssl req -x509 -new -config %s/openssl.ca.cnf -days 3650 -out %s/ca/cacert.pem -keyout %s/ca/cakey.pem -nodes -batch' % (ssl_dir, ssl_dir, ssl_dir),
@@ -317,35 +321,34 @@ def tools_update(ignore_apps=False, ignore_packages=False):
             app_fetchlist()
         except MoulinetteError:
             pass
-        app_list = os.listdir(apps_setting_path)
-        if len(app_list) > 0:
-            for app_id in app_list:
-                if '__' in app_id:
-                    original_app_id = app_id[:app_id.index('__')]
-                else:
-                    original_app_id = app_id
 
-                current_app_dict = app_info(app_id,  raw=True)
-                new_app_dict     = app_info(original_app_id, raw=True)
+        for app_id in os.listdir(apps_setting_path):
+            if '__' in app_id:
+                original_app_id = app_id[:app_id.index('__')]
+            else:
+                original_app_id = app_id
 
-                # Custom app
-                if new_app_dict is None or 'lastUpdate' not in new_app_dict or 'git' not in new_app_dict:
-                    continue
+            current_app_dict = app_info(app_id, raw=True)
+            new_app_dict = app_info(original_app_id, raw=True)
 
-                if (new_app_dict['lastUpdate'] > current_app_dict['lastUpdate']) \
-                      or ('update_time' not in current_app_dict['settings'] \
-                           and (new_app_dict['lastUpdate'] > current_app_dict['settings']['install_time'])) \
-                      or ('update_time' in current_app_dict['settings'] \
-                           and (new_app_dict['lastUpdate'] > current_app_dict['settings']['update_time'])):
-                    apps.append({
-                        'id': app_id,
-                        'label': current_app_dict['settings']['label']
-                    })
+            # Custom app
+            if new_app_dict is None or 'lastUpdate' not in new_app_dict or 'git' not in new_app_dict:
+                continue
+
+            if (new_app_dict['lastUpdate'] > current_app_dict['lastUpdate']) \
+                  or ('update_time' not in current_app_dict['settings'] \
+                       and (new_app_dict['lastUpdate'] > current_app_dict['settings']['install_time'])) \
+                  or ('update_time' in current_app_dict['settings'] \
+                       and (new_app_dict['lastUpdate'] > current_app_dict['settings']['update_time'])):
+                apps.append({
+                    'id': app_id,
+                    'label': current_app_dict['settings']['label']
+                })
 
     if len(apps) == 0 and len(packages) == 0:
         logger.info(m18n.n('packages_no_upgrade'))
 
-    return { 'packages': packages, 'apps': apps }
+    return {'packages': packages, 'apps': apps}
 
 
 def tools_upgrade(auth, ignore_apps=False, ignore_packages=False):
@@ -381,7 +384,7 @@ def tools_upgrade(auth, ignore_apps=False, ignore_packages=False):
             # ... and set a hourly cron up to upgrade critical packages
             if critical_upgrades:
                 logger.info(m18n.n('packages_upgrade_critical_later',
-                                        packages=', '.join(critical_upgrades)))
+                                   packages=', '.join(critical_upgrades)))
                 with open('/etc/cron.d/yunohost-upgrade', 'w+') as f:
                     f.write('00 * * * * root PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin apt-get install %s -y && rm -f /etc/cron.d/yunohost-upgrade\n' % ' '.join(critical_upgrades))
 
@@ -414,7 +417,7 @@ def tools_upgrade(auth, ignore_apps=False, ignore_packages=False):
 
     # Return API logs if it is an API call
     if is_api:
-        return { "log": service_log('yunohost-api', number="100").values()[0] }
+        return {"log": service_log('yunohost-api', number="100").values()[0]}
 
 
 def tools_diagnosis(auth, private=False):
@@ -422,7 +425,7 @@ def tools_diagnosis(auth, private=False):
     Return global info about current yunohost instance to help debugging
 
     """
-    diagnosis = OrderedDict();
+    diagnosis = OrderedDict()
 
     # Debian release
     try:
@@ -466,8 +469,8 @@ def tools_diagnosis(auth, private=False):
         logger.warning(m18n.n('diagnosis_monitor_system_error', error=format(e)), exc_info=1)
     else:
         diagnosis['system']['memory'] = {
-            'ram' : '%s (%s free)' % (system['memory']['ram']['total'], system['memory']['ram']['free']),
-            'swap' : '%s (%s free)' % (system['memory']['swap']['total'], system['memory']['swap']['free']),
+            'ram': '%s (%s free)' % (system['memory']['ram']['total'], system['memory']['ram']['free']),
+            'swap': '%s (%s free)' % (system['memory']['swap']['total'], system['memory']['swap']['free']),
         }
 
     # Services status
diff --git a/src/yunohost/user.py b/src/yunohost/user.py
index ec7dd539c..e6fe112e6 100644
--- a/src/yunohost/user.py
+++ b/src/yunohost/user.py
@@ -30,12 +30,17 @@ import string
 import json
 import errno
 import subprocess
-import math
 import re
+import pwd
 
 from moulinette.core import MoulinetteError
 from moulinette.utils.log import getActionLogger
 
+from yunohost.domain import domain_list
+from yunohost.hook import hook_callback
+from yunohost.app import app_ssowatconf
+
+
 logger = getActionLogger('yunohost.user')
 
 
@@ -50,12 +55,12 @@ def user_list(auth, fields=None, filter=None, limit=None, offset=None):
         fields -- fields to fetch
 
     """
-    user_attrs = { 'uid': 'username',
-                   'cn': 'fullname',
-                   'mail': 'mail',
-                   'maildrop': 'mail-forward',
-                   'mailuserquota': 'mailbox-quota' }
-    attrs = [ 'uid' ]
+    user_attrs = {'uid': 'username',
+                  'cn': 'fullname',
+                  'mail': 'mail',
+                  'maildrop': 'mail-forward',
+                  'mailuserquota': 'mailbox-quota'}
+    attrs = ['uid']
     users = {}
 
     # Set default arguments values
@@ -74,12 +79,12 @@ def user_list(auth, fields=None, filter=None, limit=None, offset=None):
                 raise MoulinetteError(errno.EINVAL,
                                       m18n.n('field_invalid', attr))
     else:
-        attrs = [ 'uid', 'cn', 'mail', 'mailuserquota' ]
+        attrs = ['uid', 'cn', 'mail', 'mailuserquota']
 
     result = auth.search('ou=users,dc=yunohost,dc=org', filter, attrs)
 
     if len(result) > offset and limit > 0:
-        for user in result[offset:offset+limit]:
+        for user in result[offset:offset + limit]:
             entry = {}
             for attr, values in user.items():
                 try:
@@ -88,7 +93,7 @@ def user_list(auth, fields=None, filter=None, limit=None, offset=None):
                     pass
             uid = entry[user_attrs['uid']]
             users[uid] = entry
-    return { 'users' : users }
+    return {'users': users}
 
 
 def user_create(auth, username, firstname, lastname, mail, password,
@@ -105,15 +110,10 @@ def user_create(auth, username, firstname, lastname, mail, password,
         mailbox_quota -- Mailbox size quota
 
     """
-    import pwd
-    from yunohost.domain import domain_list
-    from yunohost.hook import hook_callback
-    from yunohost.app import app_ssowatconf
-
     # Validate uniqueness of username and mail in LDAP
     auth.validate_uniqueness({
-        'uid'       : username,
-        'mail'      : mail
+        'uid': username,
+        'mail': mail
     })
 
     # Validate uniqueness of username in system users
@@ -125,10 +125,10 @@ def user_create(auth, username, firstname, lastname, mail, password,
         raise MoulinetteError(errno.EEXIST, m18n.n('system_username_exists'))
 
     # Check that the mail domain exists
-    if mail[mail.find('@')+1:] not in domain_list(auth)['domains']:
+    if mail[mail.find('@') + 1:] not in domain_list(auth)['domains']:
         raise MoulinetteError(errno.EINVAL,
                               m18n.n('mail_domain_unknown',
-                                     domain=mail[mail.find('@')+1:]))
+                                     domain=mail[mail.find('@') + 1:]))
 
     # Get random UID/GID
     uid_check = gid_check = 0
@@ -141,7 +141,7 @@ def user_create(auth, username, firstname, lastname, mail, password,
     fullname = '%s %s' % (firstname, lastname)
     rdn = 'uid=%s,ou=users' % username
     char_set = string.ascii_uppercase + string.digits
-    salt = ''.join(random.sample(char_set,8))
+    salt = ''.join(random.sample(char_set, 8))
     salt = '$1$' + salt + '$'
     user_pwd = '{CRYPT}' + crypt.crypt(str(password), salt)
     attr_dict = {
@@ -166,12 +166,12 @@ def user_create(auth, username, firstname, lastname, mail, password,
         with open('/etc/yunohost/current_host') as f:
             main_domain = f.readline().rstrip()
         aliases = [
-            'root@'+ main_domain,
-            'admin@'+ main_domain,
-            'webmaster@'+ main_domain,
-            'postmaster@'+ main_domain,
+            'root@' + main_domain,
+            'admin@' + main_domain,
+            'webmaster@' + main_domain,
+            'postmaster@' + main_domain,
         ]
-        attr_dict['mail'] = [ attr_dict['mail'] ] + aliases
+        attr_dict['mail'] = [attr_dict['mail']] + aliases
 
         # If exists, remove the redirection from the SSO
         try:
@@ -184,8 +184,8 @@ def user_create(auth, username, firstname, lastname, mail, password,
             with open('/etc/ssowat/conf.json.persistent', 'w+') as f:
                 json.dump(ssowat_conf, f, sort_keys=True, indent=4)
 
-        except IOError: pass
-
+        except IOError:
+            pass
 
     if auth.add(rdn, attr_dict):
         # Invalidate passwd to take user creation into account
@@ -194,7 +194,7 @@ def user_create(auth, username, firstname, lastname, mail, password,
         # Update SFTP user group
         memberlist = auth.search(filter='cn=sftpusers', attrs=['memberUid'])[0]['memberUid']
         memberlist.append(username)
-        if auth.update('cn=sftpusers,ou=groups', { 'memberUid': memberlist }):
+        if auth.update('cn=sftpusers,ou=groups', {'memberUid': memberlist}):
             try:
                 # Attempt to create user home folder
                 subprocess.check_call(
@@ -204,12 +204,12 @@ def user_create(auth, username, firstname, lastname, mail, password,
                     logger.warning(m18n.n('user_home_creation_failed'),
                                    exc_info=1)
             app_ssowatconf(auth)
-            #TODO: Send a welcome mail to user
+            # TODO: Send a welcome mail to user
             logger.success(m18n.n('user_created'))
             hook_callback('post_user_create',
                           args=[username, mail, password, firstname, lastname])
 
-            return { 'fullname' : fullname, 'username' : username, 'mail' : mail }
+            return {'fullname': fullname, 'username': username, 'mail': mail}
 
     raise MoulinetteError(169, m18n.n('user_creation_failed'))
 
@@ -223,18 +223,17 @@ def user_delete(auth, username, purge=False):
         purge
 
     """
-    from yunohost.app import app_ssowatconf
-    from yunohost.hook import hook_callback
-
     if auth.remove('uid=%s,ou=users' % username):
         # Invalidate passwd to take user deletion into account
         subprocess.call(['nscd', '-i', 'passwd'])
 
         # Update SFTP user group
         memberlist = auth.search(filter='cn=sftpusers', attrs=['memberUid'])[0]['memberUid']
-        try: memberlist.remove(username)
-        except: pass
-        if auth.update('cn=sftpusers,ou=groups', { 'memberUid': memberlist }):
+        try:
+            memberlist.remove(username)
+        except:
+            pass
+        if auth.update('cn=sftpusers,ou=groups', {'memberUid': memberlist}):
             if purge:
                 subprocess.call(['rm', '-rf', '/home/{0}'.format(username)])
     else:
@@ -265,9 +264,6 @@ def user_update(auth, username, firstname=None, lastname=None, mail=None,
         remove_mailalias -- Mail aliases to remove
 
     """
-    from yunohost.domain import domain_list
-    from yunohost.app import app_ssowatconf
-
     attrs_to_fetch = ['givenName', 'sn', 'mail', 'maildrop']
     new_attr_dict = {}
     domains = domain_list(auth)['domains']
@@ -280,11 +276,11 @@ def user_update(auth, username, firstname=None, lastname=None, mail=None,
 
     # Get modifications from arguments
     if firstname:
-        new_attr_dict['givenName'] = firstname # TODO: Validate
+        new_attr_dict['givenName'] = firstname  # TODO: Validate
         new_attr_dict['cn'] = new_attr_dict['displayName'] = firstname + ' ' + user['sn'][0]
 
     if lastname:
-        new_attr_dict['sn'] = lastname # TODO: Validate
+        new_attr_dict['sn'] = lastname  # TODO: Validate
         new_attr_dict['cn'] = new_attr_dict['displayName'] = user['givenName'][0] + ' ' + lastname
 
     if lastname and firstname:
@@ -292,34 +288,34 @@ def user_update(auth, username, firstname=None, lastname=None, mail=None,
 
     if change_password:
         char_set = string.ascii_uppercase + string.digits
-        salt = ''.join(random.sample(char_set,8))
+        salt = ''.join(random.sample(char_set, 8))
         salt = '$1$' + salt + '$'
         new_attr_dict['userPassword'] = '{CRYPT}' + crypt.crypt(str(change_password), salt)
 
     if mail:
-        auth.validate_uniqueness({ 'mail': mail })
-        if mail[mail.find('@')+1:] not in domains:
+        auth.validate_uniqueness({'mail': mail})
+        if mail[mail.find('@') + 1:] not in domains:
             raise MoulinetteError(errno.EINVAL,
                                   m18n.n('mail_domain_unknown',
-                                          domain=mail[mail.find('@')+1:]))
+                                         domain=mail[mail.find('@') + 1:]))
         del user['mail'][0]
         new_attr_dict['mail'] = [mail] + user['mail']
 
     if add_mailalias:
         if not isinstance(add_mailalias, list):
-            add_mailalias = [ add_mailalias ]
+            add_mailalias = [add_mailalias]
         for mail in add_mailalias:
-            auth.validate_uniqueness({ 'mail': mail })
-            if mail[mail.find('@')+1:] not in domains:
+            auth.validate_uniqueness({'mail': mail})
+            if mail[mail.find('@') + 1:] not in domains:
                 raise MoulinetteError(errno.EINVAL,
                                       m18n.n('mail_domain_unknown',
-                                             domain=mail[mail.find('@')+1:]))
+                                             domain=mail[mail.find('@') + 1:]))
             user['mail'].append(mail)
         new_attr_dict['mail'] = user['mail']
 
     if remove_mailalias:
         if not isinstance(remove_mailalias, list):
-            remove_mailalias = [ remove_mailalias ]
+            remove_mailalias = [remove_mailalias]
         for mail in remove_mailalias:
             if len(user['mail']) > 1 and mail in user['mail'][1:]:
                 user['mail'].remove(mail)
@@ -330,7 +326,7 @@ def user_update(auth, username, firstname=None, lastname=None, mail=None,
 
     if add_mailforward:
         if not isinstance(add_mailforward, list):
-            add_mailforward = [ add_mailforward ]
+            add_mailforward = [add_mailforward]
         for mail in add_mailforward:
             if mail in user['maildrop'][1:]:
                 continue
@@ -339,7 +335,7 @@ def user_update(auth, username, firstname=None, lastname=None, mail=None,
 
     if remove_mailforward:
         if not isinstance(remove_mailforward, list):
-            remove_mailforward = [ remove_mailforward ]
+            remove_mailforward = [remove_mailforward]
         for mail in remove_mailforward:
             if len(user['maildrop']) > 1 and mail in user['maildrop'][1:]:
                 user['maildrop'].remove(mail)
@@ -352,11 +348,11 @@ def user_update(auth, username, firstname=None, lastname=None, mail=None,
         new_attr_dict['mailuserquota'] = mailbox_quota
 
     if auth.update('uid=%s,ou=users' % username, new_attr_dict):
-       logger.success(m18n.n('user_updated'))
-       app_ssowatconf(auth)
-       return user_info(auth, username)
+        logger.success(m18n.n('user_updated'))
+        app_ssowatconf(auth)
+        return user_info(auth, username)
     else:
-       raise MoulinetteError(169, m18n.n('user_update_failed'))
+        raise MoulinetteError(169, m18n.n('user_update_failed'))
 
 
 def user_info(auth, username):
@@ -372,9 +368,9 @@ def user_info(auth, username):
     ]
 
     if len(username.split('@')) is 2:
-        filter = 'mail='+ username
+        filter = 'mail=' + username
     else:
-        filter = 'uid='+ username
+        filter = 'uid=' + username
 
     result = auth.search('ou=users,dc=yunohost,dc=org', filter, user_attrs)
 
@@ -398,28 +394,31 @@ def user_info(auth, username):
         result_dict['mail-forward'] = user['maildrop'][1:]
 
     if 'mailuserquota' in user:
-        if user['mailuserquota'][0] != '0': 
-           cmd = 'doveadm -f flow quota get -u %s' % user['uid'][0]
-           userquota = subprocess.check_output(cmd,stderr=subprocess.STDOUT,
-                                             shell=True)
-           quotavalue = re.findall(r'\d+', userquota)
-           result = '%s (%s%s)' % ( _convertSize(eval(quotavalue[0])), 
-                                             quotavalue[2], '%')
-           result_dict['mailbox-quota'] = {
-               'limit' : user['mailuserquota'][0],
-               'use' : result
-           }
+        if user['mailuserquota'][0] != '0':
+            cmd = 'doveadm -f flow quota get -u %s' % user['uid'][0]
+            userquota = subprocess.check_output(cmd, stderr=subprocess.STDOUT,
+                                              shell=True)
+            quotavalue = re.findall(r'\d+', userquota)
+            result = '%s (%s%s)' % (_convertSize(eval(quotavalue[0])),
+                                    quotavalue[2], '%')
+            result_dict['mailbox-quota'] = {
+                'limit': user['mailuserquota'][0],
+                'use': result
+            }
         else:
-           result_dict['mailbox-quota'] = m18n.n('unlimit')
- 
+            result_dict['mailbox-quota'] = m18n.n('unlimit')
+
     if result:
         return result_dict
     else:
         raise MoulinetteError(167, m18n.n('user_info_failed'))
 
+
 def _convertSize(num, suffix=''):
-    for unit in ['K','M','G','T','P','E','Z']:
+    for unit in ['K', 'M', 'G', 'T', 'P', 'E', 'Z']:
         if abs(num) < 1024.0:
             return "%3.1f%s%s" % (num, unit, suffix)
+
         num /= 1024.0
+
     return "%.1f%s%s" % (num, 'Yi', suffix)