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Text File | 1992-03-08 | 17KB | 434 lines

CRONJR ver 2.28 From Software Shorts Requirements ------------ MS-DOS based machine running MS-DOS 3.30 or higher. MS-DOS versions below 3.30 may be used, but are not recommended, since they require CRONJR to use more memory. Background ---------- The reason for designing CRONJR was for lack of anything better in the MS-DOS world. Simple but powerful programs like cron (part of AT&T's Unix) or Sleeper (public domain for HP's MPE) are non existent for PC's. With more and more companies moving from mini-computers to PC based LANs, one of the many things that has been lost was the ability to schedule the nightly reporting and maintenance programs needed to keep a business working during the day. Sure, it's possible to just write a large batch file that will run all your programs one after another. That solution is fine if it meets your needs. But if you need programs to run at specific times, and especially if your business revolves around a LAN, then this product is for you. The solution ------------ There are 3 methods of scheduler implementation in a DOS environment. Method 1 Make a background RAM resident program that will pop up when it is time to run the tasks. Method 2 Make a foreground program that loads the tasks as child processes. Method 3 Make a transient program that is only in memory when it is needed. Therefore, all memory is available for the task. Faults for method 1 -------------------- The last thing the world needs is another RAM resident program to eat up memory, steal clock cycles, and substitute custom interrupt vectors. Most LAN users already use 20-70k for their network shell, and even more if they are running a NETBIOS emulator. The way most resident schedulers work is to stuff the keyboard when it is time to execute a task. This method can be seen in various automatic tape backup programs. This method is unreliable since the assumption is made that the DOS prompt is available, the command line is clear, and the path is set. Faults for method 2 ------------------- This method requires too much memory. If you want to run a batch file then you have to load another version of COMMAND.COM on top of the parent scheduler. Why method 3 is so swell ------------------------ 1. It is so simple. It relies heavily on two simple operating system level batch files. 2. It is not RAM resident so it uses no memory(*). * The dreaded asterisk - If you are using a DOS version below 3.3 then around 23k is lost because COMMAND.COM needs to be invoked a second time. It is strongly recommend that DOS 3.30 or above is used. How it works ------------ 1. The schedule file CRONJR.SCH is created by you. It contains the timing parameters for the tasks to be executed. 2. The master batch file, CRONJR.BAT, is loaded from the command line. That is your last intervention. 3. The work file, CRONWK.BAT, is deleted by CRONJR.BAT. 4. The scheduler program, CRON.EXE, is loaded and the schedule file CRONJR.SCH is read. 5. When the time comes to execute a process CRON.EXE dumps its scheduling information to CRONJR.JOB, writes the CRONWK.BAT bat file and unloads from memory to return control to CRONJR.BAT. 6. If CRONJR.BAT can find CRONWK.BAT then the CRONWK.BAT work file is called/executed. 7. Upon completion of CRONWK.BAT, control is returned to CRONJR.BAT which then executes CRONJR.BAT (thus ending the original CRONJR.BAT execution) with the parameter RELOAD which is passed to CRON.EXE in step 4, which causes the file CRONJR.JOB to be loaded rather than the file CRONJR.SCH . Hard to follow? Try this one. It is the remedial version. CRONJR.BAT -> CRON.EXE -> CRONWK.BAT (YOUR TASK) ->CRONJR.BAT A. B. C. A. Installation ------------ Create a directory for CRONJR, any name will do, and copy the CRON.EXE program into the new directory. If you are going to use CRONJR on a LAN with multiple machines running CRONJR, then you must make a separate directory for each machine. Examples: F:\CRON\386 F:\BOB\CRON F:\CRON\486 F:\ACCTNG\CRON Each directory must contain its own CRONJR.SCH file and its own unique CRONJR.BAT file. A path may be set to point to the location of CRON.EXE. For each CRONJR directory created, type CRON START at their respective DOS prompt. Such as: F:\CRON\386>cron start For added security we recommend disabling the DOS Shell by using the DISABLE parameter. Such as: F:\CRON\386>cron start disable Either of these will create the CRONJR.BAT file which is specific to its home directory. If you type out the CRONJR.BAT file you will understand. Create a flat ASCII file (no tabs) named CRONJR.SCH or edit the one on the distribution diskette. Enter one task per line using the following format. minute hour day_of_month month day_of_week executable parm_list Example ------- 50 16 * * MOTUWETHFR f:\public\bin\killuser.EXE 0 17 * * MOTUWETHFR f:\mtn_tape\databack.bat 0 5 * * MO g:\acctng\weekly.bat 0 1 1 * SUMOTUWETHFRSA G:\ACCTNG\MONTHEND.EXE 0 1 1 1 SUMOTUWETHFRSA G:\ACCTNG\YEARLY.EXE 49 16 * * MOTUWETHFR C:\FUNNY\GOHOME.EXE 2i * * * MOTUWETHFR F:\stream\kevin.bat * 1i * * MOTUWETHFR q:\hourly\bak2work.exe 30 12 * * WE nopath.com 06 30 * * SA u:\palitape\tna2tape.exe /a q /optic Type CRONJR at the DOS prompt and you are finished. Field definitions ----------------- minute......: the minute of the hour you want your schedule to execute, 0 through 59. hour........: the hour of the day in military time, 0 through 23. day_of_month: the day of the month 1 through 31. month.......: the month of the year 1 through 12. day_of_week.: the day of the week, SU MO TU WE TH FR SA. executable..: a DOS executable string, .BAT, .EXE, and .COM files with a maximum combined path of 64 characters. EXTENTIONS MUST BE USED!!!!!! parm_list...: optional parameters to be passed to the executable. Maximum of 128 characters. Wild cards and increments ------------------------- *: execute on every occurrence - not used by day_of_week . i: execute in increments - only applies to minute and hour. The 7th line in the example shows 2i which means execute in 2 minute increments. In theory this task could be executed 30 times a hour. Obviously * must be used for every level after the first i . Combinations of i in the minute and hour are not allowed. The expected outcome is that only the hour increment will be used. If 'i' is used with the hour, then the minute should be *, otherwise execution will occur in x hour increments, but only on the specified minute. Thus 30 1i does not mean execute every 90 minutes, but execute hourly on the 30th minute of the hour. Launch time ----------- Task checking and launching occur on the 1st second of the minute. EXTREMELY IMPORTANT ------------------- Be very careful when assigning launch times. A 'feature' of CRONJR is that it only launches tasks when CRON.EXE is resident. Example: you have 2 tasks set to execute at 19:00, each takes 20 minutes to run, and few tasks scheduled at 19:15. At 19:00 all 19:00 tasks are tagged for launching and the first task will be launched at 19:00. The 2nd task will be launched when CRON.EXE is reloaded and thus effectively launched at 19:20. Well it is now 19:40 and all tasks scheduled from 19:01 through 19:40 have missed their launch window. To prevent this from happening you should do the following. Schedule enough time between tasks. The 19:15 tasks in the example should have been set later to 20:00, or earlier to 19:00. Had they been scheduled at 19:00 then they would have run as part of the 19:00 launching. Proper scheduling ----------------- The best way to debug a faulty schedule is to run CRON.EXE instead of CRONJR.BAT, and use the F1 key to exit to DOS and change the time. Inspect the CRONWK.BAT file that is created. There is no limit to the number of tasks you can put into the CRONJR.SCH file. Common problems --------------- CRONJR program is running, and exits to DOS and does nothing. Problem: Running CRON instead of CRONJR. Problem: Did not run CRON START in the execution directory. CRONJR does not execute the programs listed in CRONJR.SCH Problem: Could not find the programs. Need to specify the path in the CRONJR.SCH file or verify that programs are in the current directory. Problem: You did not specify .BAT, .EXE, or .COM . Problem: Your scheduling parameters are incorrect. Most likely day_of_the_week not included. I.e. You are testing on Saturday a job you have set up to run Monday through Friday. CRONJR playes this obnoxious fight song when it executes. Problem: Running the evaluation version. The competition --------------- It was mentioned earlier that there are no programs available similar to CRONJR. Well that is no longer true. There is a product called PS-Batch from Brightwork Development. Its list price is around $595.00, it must be licensed per file server, it uses about 40k of memory and it is limited to Netware. CRONJR on the other hand is available for $35.00, licensing is per site - not batch station or server, it uses 0k of memory and will work on ANY LAN or stand alone PC. I am sure PS-Batch is a fine product and has many more features than CRONJR. Many of these features were purposely designed out of the original versions of CRONJR. Anomalies and hints ------------------- There are two known anomalies and one other point that you need to remember. Anomaly 1. Cronjr only executes tasks on the 1st second of the minute. Example. If you had 3 tasks that each take 5 seconds to complete, and they are all scheduled to launch at 19:00 then they will be effectively launched at 19:00, 19:01 and 19:02. This feature was designed into the product. Anomaly 2. Anomaly 2 arises out of anomaly 1. Example. If you set up a schedule that has 3 jobs, each set to run in increments of 10 minutes (10i * * * ...), you would assume that they would execute at the 10, 20, 30, 40, 50, 00 minute clock demarcations (assuming that the first launch minute was hh:00) and always launch one after the other. In reality this is not true. The first launching schedule would look like this. 1a. Job #1 launches at the first available minute. 2a. Job #2 launches at the first available minute after Job #1 completes. 3a. Job #3 launches at first available minute after Job #2 completes. The second and subsequent launchings might look like this. 1b. Job #1 launches 10 minutes after its's first launching or at the first available minute after Job #3 finishes or it may launch the first available minute after Job #1 if Job #1 takes more than 10 minutes. 2b. and 3b. Who knows. The best way to get around this confusion is to do one of three things. 1. Carefully plan and test your incremental launchings. 2. Rather than make your launchings incremental, make them minute specific. This may involve multiple line entries into the CRONJR.SCH file for he same job at different times. 3. Make Jobs 1, 2 and 3 one job. The one thing you must remember. The CRONJR.SCH file is only loaded at the initial load time. If you are running CRONJR on a LAN and CRONJR is running on a remote machine and you modify the remote machine's CRONJR.SCH file, the remote CRONJR will not reflect any of the changes made in the new CRONJR.SCH file until the remote CRONJR is aborted and reloaded. Getting legal ------------- Software Shorts hereby disclaims all warranties relating to this software, whether expressed or implied, including without limitation any implied warranties of merchantability or fitness for a particular purpose. Software Shorts will not be liable for any special, incidental, consequential, indirect or similar damages due to loss of data or any other reason, even if Software Shorts or an agent of Software Shorts has been advised of the possibility of such damages. Software Shorts will not be liable for any damages due to malicious third party augmentation of the executable program. In no event shall Software Shorts's liability for any damages ever exceed the price paid for the license to use software, regardless of the form of the claim. The person using the software bears all risk as to the quality and performance of the software. Acknowledgements ---------------- Unix, cron and AT&T are registered trademarks of American Telephone and Telegraph Corporation. MPE and HP are copyrights of Hewlett Packard Company. Sleeper is available through INTEREX MS-DOS is a registered trademarks of Microsoft Corporation. NetWare is a registered trademark of Novell Incorporated PS-Batch is a trademark of Brightwork Development Incorporated Software Shorts is not affiliated with any of the above mentioned companies. Technical Support ----------------- Questions can be sent to CompuServe ID 70731,2507 Licensing --------- CRONJR is licensed by site. This means that if you have 50 machines in 1 building then they can all use the same copy of the software, with or without a LAN. Or if you have 10 offices in different buildings, then you need to purchase 10 copies of the software. Or if those 10 offices are in different buildings but are connected to a WAN to your office with the 50 machines and the one purchased copy, then those 10 offices still have to purchase their own copies of the software since they are in different building. One last word ------------- Software Shorts is dedicated to the creation and dissemination of short, single focus, utility programs for programmers. Hence the name Software Shorts. In the tradition of true software geeks, Software Shorts believes utility programs should be inexpensive, if not free, and in the hands of as many people as possible. However, Software Shorts utility programs may not be distributed by any individual or corporation as part of a commercial software release, unless the utility has been licensed to that individual or corporation for such distribution. The first version of CRONJR was released in November of 1988.