cron-v2.py

#!/usr/bin/python

##############################################################################
# Emilio Schapira
# Copyright (C) 2003 Advanced Interface Technologies, Inc.
# http://www.advancedinterfaces.com
# http://sourceforge.net/projects/pycron/
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##############################################################################

#
#      Chapman Siu
#      chappers.github.com
#      Matching function changed to allow for cron behaviour for dashes


"""
usage: cron [crontab_file_name [log_file_name [pid_file_name]]]
       This is a minimal cron clone that can be used in windows.
       It writes a log in the current directory, and looks for the
       crontab file in the current directory unless otherwise specified by
       the command line argument.
"""

import time
import os
import sys
import string

def log(msg):
    f = file(logFileName,'a')
    f.write(time.ctime(time.time()) + " " + msg + "\n")

def run(command):
    log(command)
    try:
        # This is the only windows dependant call
        # We use start because we want to spawn the
        # shell command in another process, and not wait
        if os.name == 'nt':
            os.system('start ' + command)
        else:
            os.system(command)
    except:
        log('cron: last command failed to start')

#
#   Matching Algorithm chapman's edit
#
def listing(expr):
    listing = [dash(x) for x in string.split(expr,',')]
    return [item for sublist in listing for item in sublist]

def dash(expr):
    value = [int(x) for x in string.split(expr,'-')]
    return range(min(value),max(value)+1)

def match(value, expr):

    if expr == '*':
        return 1
    values = listing(expr)

    #chapman edit to account for dashes
    for v in values:
        if v == value:
            #here for if there are no dashes
            return 1
    return 0

#
#   end matching algorith
#

def calcNextTime():
    # Calculate next time with exact seconds.
    tt = time.localtime(time.time() + 60)
    tt = tt[:5] + (0,) + tt[6:]
    return time.mktime(tt)

crontabFileName = "crontab.tab"
logFileName = "cron.log"
pidFileName = "cron.pid"

try:
    crontabFileName = sys.argv[1]
    logFileName = sys.argv[2]
    pidFileName = sys.argv[3]
except:
    pass

#Write the pid in the current directory.
f = file(pidFileName,'w')
f.write(str(os.getpid()))
f.close()

# Log cron start
log('cron: started with file %s' % crontabFileName)

nextTime = calcNextTime()

# Loop forever
while 1:

    # Sleep for the time remaining until the next exact minute
    currentTime = time.time()



    if currentTime < nextTime:
        # Add a fraction of a second to make sure we are in
        # the right second (just for prettier logs)
        time.sleep(nextTime-currentTime+.1)

    # Check if the time has changed by more than two minutes. This
    # case arises when the system clock is changed. We must reset the timer.
    if abs(time.time() - nextTime) > 120:
        log('Adjusted system clock.')
        nextTime = calcNextTime()

    # Build a tuple with the current time
    curTuple = time.localtime(nextTime)

    # Read the crontab file
    try:
        lines = file(crontabFileName,'r').readlines()
        lineNum = 1
        for line in lines:
            # Ignore comments
            if line[0] != '#' and len(string.strip(line)) != 0:
                try:
                    tokens = string.split(line)
                    # See if the cron entry matches the current time
                    # minute
                    timeMatch = match(curTuple[4],tokens[0])
                    # hour
                    timeMatch = timeMatch and match(curTuple[3],tokens[1])
                    # day
                    timeMatch = timeMatch and match(curTuple[2],tokens[2])
                    # month
                    timeMatch = timeMatch and match(curTuple[1],tokens[3])
                    # weekday (in crontab 0 or 7 is Sunday)
                    weekday = curTuple[6]+1
                    matchWeekday = match(weekday,tokens[4]) or (weekday == 7 and match(0,tokens[4]))
                    timeMatch = timeMatch and matchWeekday

                    if timeMatch:
                        run(string.join(tokens[5:]))
                except:
                    log('cron: error parsing line %i of %s' % (lineNum, crontabFileName))

            lineNum = lineNum + 1
    except:
        log('cron: error opening %s file' % crontabFileName)
        print 'error'

    # Calculate the time for the next iteration (60 seconds later)
    nextTime = nextTime + 60

cron-v3.py

"""
cron scheduler
by Chapman Siu

Based on script written by Emilio Schapira

---

This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

"""

from datetime import datetime, timedelta
import time
import subprocess
import os
import re
import sys
 
def log(msg):
    log_msg = datetime.now().time().strftime('%H:%M:%S') + " " + msg + "\n"
    with file(log_file, 'a') as f: f.write(log_msg)
    
def run(command):
    log(' '.join(command))
    try: subprocess.call(command)
    except: 
        print command
        log('cron: last command failed to start')
        
def cleanCommand(txt):
    """remove extra quotation marks if it exists"""
    if txt[0] == '"' and txt[-1] == '"':
        return txt[1:-1]
    else:
        return txt
 
def match(date_part, cron_date):
    """
    Parameters:
        date_part : the date which is gained from the system
        cron_date : the date which is parsed from the crontab.tab file
    """
    time_cron = {0:4, 1:3, 2:2, 3:1, 4:6}  
    # necessary to 'convert' python time to cron time (and vice versa)    
    
    cron_index = [(index, dt) for index, dt in enumerate(cron_date) if dt != '*']
    if len(cron_index) == 0: return True # must be "* * * * *"    
    
    for (index, date) in cron_index: 
        if '-' not in date:
            if str(date_part[time_cron[index]]) != date: return False    
            return True
        else:
            dt_range = [str(x) for x in range(int(date.split('-')[0]),int(date.split('-')[1])+1)]
            if str(date_part[time_cron[index]]) not in dt_range: return False
            return True

# main

cron_tab = "crontab.tab"
log_file = "cron.log"
pid_file = "cron.pid"
 
try:
    (cron_tab, log_file, pid_file) = sys.argv[1:]
except:
    pass
 
with file(pid_file, 'w') as f: f.write(str(os.getpid()))
 
# perform scheduling, lambda function removes seconds component of time
next_time = (lambda t: t - timedelta(seconds = t.second))(datetime.now() + timedelta(minutes=1))
 
while True:  
    current_time = datetime.now()
    
    if current_time < next_time:
        time.sleep((next_time-current_time).seconds + .1)    
    
    try:
        tab = file(cron_tab, 'r').readlines()
        for entry in tab:
            if entry[0] == '#' or len(entry.strip()) == 0: continue
            try:
                # ensure that quoted are correctly split
                tokens = [cleanCommand(x) for x in re.findall(r'\"[^\"]*\"|\S+', entry)]
                (date, command) = (tokens[:5], tokens[5:])
                if match(next_time.timetuple(), date): run(command)
            except:
                log('cron: error parsing %s' % entry)
    except:
        log('cron: error opening %s file' % cron_tab)
        print 'error'
    next_time = next_time + timedelta(minutes=1)

cron.py

from datetime import datetime, timedelta
import time
import subprocess
import os
import re
import sys

def log(msg):
    log_msg = datetime.now().time().strftime('%H:%M:%S') + " " + msg + "\n"
    with file(log_file, 'a') as f: f.write(log_msg)
    
def run(command):
    log(' '.join(command))
    try: subprocess.call(command)
    except: 
        print command
        log('cron: last command failed to start')
        
def cleanCommand(txt):
    """remove extra quotation marks if it exists"""
    if txt[0] == '"' and txt[-1] == '"':
        return txt[1:-1]
    else:
        return txt

def match(date_part, cron_date):
    # mapping from python's time library to cron
    time_cron = {0:4, 1:3, 2:2, 3:1, 4:6} 
    
    cron_index = [(index, dt) for index, dt in enumerate(cron_date) 
                              if dt != '*']
    if len(cron_index) == 0: return True # must be "* * * * *"
    for (index, date) in cron_index: 
        if str(date_part[time_cron[index]]) != date: return False    
    return True

# main

cron_tab = "crontab.tab"
log_file = "cron.log"
pid_file = "cron.pid"
 
try:
    (cron_tab, log_file, pid_file) = sys.argv[1:]
except:
    pass

with file(pid_file, 'w') as f: f.write(str(os.getpid()))

# perform scheduling, lambda function removes seconds component of time
next_time = (lambda t: t - timedelta(seconds = t.second))(datetime.now() + 
                                                        timedelta(minutes=1))

while True:  
    current_time = datetime.now()
    
    if current_time < next_time:
        time.sleep((next_time-current_time).seconds + .1)    
    
    try:
        tab = file(cron_tab, 'r').readlines()
        for entry in tab:
            if entry[0] == '#' or len(entry.strip()) == 0: continue
            try:
                # ensure that quoted are correctly split
                tokens = [cleanCommand(x) for x in re.findall(r'\"[^\"]*\"|\S+', entry)]
                (date, command) = (tokens[:5], tokens[5:])
                if match(next_time.timetuple(), date): run(command)
            except:
                log('cron: error parsing %s' % entry)
    except:
        log('cron: error opening %s file' % cron_tab)
        print 'error'
    next_time = next_time + timedelta(minutes=1)