WinCron 1.91
| Related Links: | ||
| CronIco | WinCron management tool | |
| CronLog | manages your WinCron log files | |
INTRODUCTION:
WinCron is basically a Windows implementation of the UNIX cron program.
WinCron runs under Windows 95, 98 & Windows NT. The main advantage
this program has over many of the event scheduling programs already out
there (besides being free) is that it can read the event table as a text
file from any drive. This allows you to alter the events that are being
scheduled without having to have access to the console of the computer
that WinCron is running on. Editing the text file can be done from any
machine that has sufficient rights to alter the file.
INSTRUCTIONS FOR USE:
WinCron was written in Visual Basic 6.0 and requires standard VB libraries (MSVBVM60.DLL & OLEAUT32.DLL).
The event (crontab) file is limited to 1000 lines. If you should
need more then that, a second instance of WinCron can be launched and a
different event file can be specified for the second instance. WinCron
uses the same convention as many UNIX crontab files, a plain text file
with each line having six fields separated by one or more spaces. The logical
operator between all fields is "AND"; therefore, every field must be true
before the instruction will be executed.
The fields are as follows:
1. Minute (0-59)
2. Hour (0-23)
3. Day of Month (1-31)
4. Month (1-12)
5. Day of week (0-6) (0 being Sunday)
6. The instruction you wish to execute.
Example entry:
01 02 03 *
* c:\batch\cleanup.bat
This line would start the "cleanup.bat" batch file at 00:01 (02:01am)
on the third day of every month, regardless of the day of the week.
It is also acceptable to schedule multiple times for a program to
run by separating entries with a comma. If this is done, you should use
two digits for each entry in the "Minute", "Hour", and "Day of Month fields".
In the "Day of Week" field, each entry must be a single digit. There cannot
be any spaces between the comma-separated entries.
Example:
01,02,03 01 01
* 1,2,3,4,5 c:\batch\cleanup.bat
Additional logical functionality is available through the use of
a "NOT" operator. Acceptable symbols for a logical "NOT" are "-" or "!".
This allows an event to be started at times that Do Not match the entry
in the event file. It is important to keep in my that the logical AND is
still used between fields. So in the below example the cleanup.bat file
wouldn't run on any day that was either the 13th or a Friday.
Example:
01 06 * !13
* !5 c:\batch\cleanup.bat
To create an entry that runs everyday except Friday the 13th you would have to set it up as follows:
01 06 * !13
* * c:\batch\cleanup.bat
01 06 * 13
* !5 c:\batch\cleanup.bat
Multiple values with the "NOT" operator may be included in the same
field if separated by commas. There cannot be any spaces between the comma-separated
values. However, if there is one logical "NOT" operator in the field, all
values within the field will be considered to be preceded by the "NOT"
operator. This means that !1,!2 is the same as !1,2.
Example:
01 * !07,!13
* !5 c:\batch\cleanup.bat
WinCron can be used to schedule events that are to be run only once.
To use this functionality place an @ symbol at the beginning of the first
(the minute) field. For obvious reasons, wildcards cannot be used when
running a program only once. The last field (the day of week field) is
used as a year field when scheduling an event to run only once. All fields
must be filled in or the line will be ignored.
Example:
@01 01 01 01 1998 c:\batch\cleanup.bat
Starting a line with "@launch" will cause that line to be passed
to the operating system's command interpreter as soon as WinCron launches.
This is particularly useful for starting CronIco at the same time WinCron
is launched.
Example:
@launch c:\batch\startup.bat
Starting a line with "#" will cause that line to be ignored, so
remarks may be placed in the event (crontab) file. The "#" should appear
as the first character of the line and must be followed by at least one
space. Remark lines count against the 1000 line maximum of the event file.
Example:
# This is a comment line
Because Windows 95 and Windows NT have slightly different ways of
initiating an asynchronous process, it is recommend that you place the
commands to be run in a batch file and use WinCron to start the batch file.
This will allow you to set any parameters or handle any decision making
logic outside of the WinCron program.
Using batch files also allows you to use MS-DOS shell switches to
control how the program being launched is handled. Windows .pif (shortcut)
files can also be used to control how the batch file is run. Because this
software is often run on servers, I have attempted to leave most program
control functionality to the shell in the interest of stability.
To start WinCron, simply launch it from the command line or from
a short cut. The path and file name of the crontab file MUST be specified
at the command line (i.e. WinCron f:\util\crontab.txt). The only purpose
of the large button in the middle of the main form is to check if the program
is still responding. Pressing this button updates the button's caption
to indicate current status and time.
Double Clicking on the text box that shows the crontab file being
used launches Microsoft Notepad (if it is in the system path) to edit the
file.
The program reloads the event table every 60 seconds. The switch
/NoUpdate can be used to prevent WinCron from updating the crontab file.
If this switch is used, WinCron will only load the crontab file once when
first launched.
Example:
WinCron f:\system\util\crontab.txt /NoUpdate
There is also a /Hide switch that has been added at the request
of several sysadmins. This will prevent the user from being able to see
that WinCron is running; however, this means the only way for the sysadmin
to check on the program is to hit crtl-alt-del and look at the task list.
Example:
WinCron f:\system\util\crontab.txt /NoUpdate /Hide
Logging can be enabled by using the /Log switch at the command line.
WinCron only logs errors and program launches. If the exit status of a
program is needed, then the batch file used to the launch the program must
be used to record this information. The log file is always named the same
as the crontab file with an extension of .log appended to the end. That
means that if you name your crontab file "crontab.txt", the log file will
be named "crontab.txt.log". This has been known to cause problems on systems
where the crontab file is being stored on a network drive that does not
support long file names. If you run into this problem, my suggestion is
to simply call the crontab file "crontab" with no extension, so that appending
.log will result in a log file named "crontab.log". Double Clicking on
the text box that shows the log file size will launch Microsoft Notepad
(if it is in the system path) to view the file. If the log size exceeds
5 Megabytes the text box showing log file size will change to color to
red.
Example:
WinCron f:\system\util\crontab.txt /NoUpdate /Hide /Log
There has been some debate as to how to handle errors in a cron
type program. The default action is for WinCron is to simply fail and exit
on any error. The reason for this is that often cron programs are used
to schedule several events in a specific sequence. A lost network connection
or similar event could cause unpredictable results. The safest way to handle
errors seems to be halting all events until the situation can be evaluated.
If you would prefer WinCron to continue to process events after errors,
the /ContinueOnError switch may be used. Note: Depending on your system
the program may still fail and exit if logging is switched on and the log
file becomes inaccessible.
Also remember, multiple instances of WinCron can be launched on
the same computer. Each instance can be launched with different switches,
so a table containing events that must be run in sequence and one containing
unsequenced events can both dealt with in different modes on the same machine.
Example:
WinCron f:\system\util\crontab.txt /NoUpdate /Hide /Log /ContinueOnError
I would like to extend special thanks to cydo@rype.de
who developed CronIco.
I hope that this program is useful to you. I can make no claim as
to this software's stability or value. It is being offered as is. Use at
your own risk. If you find it useful, all I ask is that you please email
me at graysteel@erols.com just
so I know that it's useful to someone. The Author reserves all copyrights.
Permission is granted to any individual or institution to use, copy, or
redistribute this executable so long as it is not modified and that it
is not sold for profit. Also, feel free to email any suggestions for revisions
to the program.
REVISION HISTORY
--1.91--
Compiled with VB 6.0 rather then VB 4.0
@launch functionality added
"Heartbeat" function for CronIco added
Blank lines now allowed in crontab file for neater formatting
Logging detail now includes task ID or launch failure
--V1.84--
Carriage return no longer needed after the last line in crontab
file
--V1.83--
Yet again more tolerant field parsing
Added small command line help screen with /? or /help
--V1.82--
Font display error on some systems fixed
Wording change in error reporting
--V1.81--
Graphical interface switch setting added
WinCron launch now logged (for security reasons)
Slightly reduced CPU load on event testing
--V1.71--
Logical NOT operator added
Log file size indicator added
Improved file sharing of log files
Reduced CPU load on disk read
More tolerant field parsing
Limited crontab error testing
--V1.61---
@ Functionality added
/NoUpdate bug fixed
Reduced CPU load and delay on start up
Improved sharing of crontab file