Crontab file syntax check

cron-file-syntax-check.py

#!/usr/bin/python
import argparse
import os
import re

'''
 ****    Crontab file syntax checking    ***
 Useful for scripts stored under /etc/cron.d
 and for automating crontab task distribution
'''

class FileNotFoundException(Exception): pass
class ParseErrorException(Exception): pass
class UnknownPredefinedKeywordException(Exception): pass
class UnknownTimeEntryException(Exception): pass
class NoUserFoundException(Exception): pass
class InvalidStateException(Exception): pass

PREDEFINED = [ 'yearly', 'annually', 'monthly',
               'weekly', 'daily', 'hourly', 'reboot' ]

R_comment = re.compile(r'^#')
R_predefined_keywords = re.compile(r'^@')
R_interval = re.compile(r'\*\/[0-9]+')
R_once_every = re.compile(r'[0-9]+')
R_always = re.compile(r'\*')
R_user = re.compile(r'^[a-z0-9_]+')

def is_none(v):
  return v is None

def read_file(parameters):
  if not os.path.exists(parameters.file):
    raise Exception('File not found')
  cron_file = []
  with open(parameters.file, 'r') as f:
    cron_file = [ line.strip() for line in f.readlines() ]
  return cron_file

def check_time_entry(entry):
  if not is_none(R_always.match(entry)):
    return 'always'
  elif not is_none(R_once_every.match(entry)):
    return 'once'
  elif not is_none(R_interval.match(entry)):
    return 'interval'
  elif not is_none(R_user.match(entry)):
    return 'user'
  return None

def parse_file(parameters):
  cron_file = read_file(parameters)
  with_user = parameters.user
  for linenum, line in enumerate(cron_file):
    linenum += 1
    ''' skip commented and empty lines '''
    if line.strip() == "" or not is_none(R_comment.match(line)):
      continue
    if not is_none(R_predefined_keywords.match(line)):
      if not line.split()[0].strip('@') in PREDEFINED:
        raise UnknownPredefinedKeywordException('Line %d' % linenum)
        return False
    if with_user:
      parameters = 6
    else:
      parameters = 5
    time_entries = []
    for status in [ check_time_entry(entry) for entry in line.split()[:parameters] ]:
      if is_none(status):
        raise UnknownTimeEntryException('Line %d' % linenum)
      time_entries.append(status)
    for position, state in enumerate(time_entries[:-1]):
      if not state in [ "once", "always", "interval" ]:
        raise InvalidStateException('Line %d, Entry %d' % (linenum, position + 1))
    if with_user:
      if time_entries[-1] != 'user':
        raise NoUserFoundException('Line %d' % linenum)
  return True

if __name__ == "__main__":
  argparser = argparse.ArgumentParser('Cron file syntax check')
  argparser.add_argument('-f', '--file', help='File to check.', required=True)
  argparser.add_argument('-u', '--user', help='Add user in syntax (for scripts in /etc/cron.d).', required=False, default=False, action='store_true')
  parameters = argparser.parse_args()
  
  if parse_file(parameters):
    print 'ok'
  else:
    print 'error'
  

Hi, nice script .... but I tested the script with the following file, and it didnt throw an error (the first line is wrong it is missing one *

crontab for process2

05 * * * process2-staging --date=date +"\%Y\%m" --date="1 sec ago"
06 * * * * process2-staging --date=date +"\%Y\%m\%d" --date="1 sec ago"