Add cleanup method that removes user accounts

This method will remove all users that have id over 1000. In most
systems this will remove all normal user accounts besides the first
one. This method will not run by default.

image_creator/os_type/unix.py

@@ -70,6 +70,49 @@ class Unix(OSBase):
 
         return users
 
+    @exclude_task
+    def data_cleanup_user_accounts(self, print_header=True):
+        """Remove all user account with id more than 1000"""
+
+        if print_header:
+            output('Removing all user accounts with id greater than 1000')
+
+        # Remove users from /etc/passwd
+        passwd = []
+        removed_users = {}
+        for line in self.g.cat('/etc/passwd').splitlines():
+            fields = line.split(':')
+            if int(fields[2]) > 1000:
+                removed_users[fields[0]] = fields
+            else:
+                passwd.append(':'.join(fields))
+
+        self.g.write('/etc/passwd', '\n'.join(passwd) + '\n')
+
+        # Remove the corresponding /etc/shadow entries
+        shadow = []
+        for line in self.g.cat('/etc/shadow').splitlines():
+            fields = line.split(':')
+            if fields[0] not in removed_users:
+                shadow.append(':'.join(fields))
+
+        self.g.write('/etc/shadow', "\n".join(shadow) + '\n')
+
+        # Remove the corresponding /etc/group entries
+        group = []
+        for line in self.g.cat('/etc/group').splitlines():
+            fields = line.split(':')
+            # Remove groups tha have the same name as the removed users
+            if fields[0] not in removed_users:
+                group.append(':'.join(fields))
+
+        self.g.write('/etc/group', '\n'.join(group) + '\n')
+        
+        # Remove home directories
+        for home in [field[5] for field in removed_users.values()]:
+            if self.g.is_dir(home) and home.startswith('/home/'):
+                self.g.rm_rf(home)
+
     def data_cleanup_passwords(self, print_header=True):
         """Remove all passwords and lock all user accounts"""
 
@@ -85,7 +128,7 @@ class Unix(OSBase):
 
             shadow.append(":".join(fields))
 
-        self.g.write('/etc/shadow', "\n".join(shadow))
+        self.g.write('/etc/shadow', "\n".join(shadow) + '\n')
 
     def data_cleanup_cache(self, print_header=True):
         """Remove all regular files under /var/cache"""