Prerequisite: To create and use BAT (batch) files you need to be familiar with running GEMPACK from the command-prompt (also called 'DOS box'). You may need to review this page.
When working on a project you might find yourself repeatedly running the following commands from the command-prompt:
tablo -sti model3.sti generate GSS, GST files for GEMSIM gemsim -cmf sim1.cmf run simulation 1 gemsim -cmf sim2.cmf run simulation 2 gemsim -cmf sim3.cmf run simulation 3
You would type the black text above (not the explanatory red text). Each time the TAB file changed, you would need to re-run all 4 commands. This might become tedious !
To speed your work, you might create a text file, DoSims.BAT, containing the lines:
tablo -sti model3.sti gemsim -cmf sim1.cmf gemsim -cmf sim2.cmf gemsim -cmf sim3.cmf
Then if you typed at the command-prompt:
all 4 commands would be executed automatically -- perhaps while you went for coffee!
Although handy, DoSims.BAT has some weaknesses: for example, it will not alert you if one of the commands failed for some reason. The sections below show how to make BAT files more robust.
As well as saving effort, BAT (or batch) files have several other advantages:
Consider the following BAT file for a recursive-dynamic (one-year-at-a-time) CGE model:
tablo -sti dynagem.sti gemsim -cmf year2001.cmf gemsim -cmf year2002.cmf gemsim -cmf year2003.cmf gemsim -cmf year2004.cmf
Suppose that year2001.cmf reads base2001.har and produces an updated database y2002.har; year2001.cmf reads y2002.har to produce y2003.har, and so on. Suppose you have run this BAT several times before, and now you run it again over lunch-time with altered shocks. If the first (year2001) simulation crashed, it is possible that the second (year2002) simulation would run OK, using as input a file y2002.har produced yesterday. You could return from your lunch and never realize that an error had occurred!
To avoid such a danger, your BAT file should enforce the following rule:
First, delete all files that you expect to produce.
The revised BAT file might read (red text not included):
del *.log delete all LOG files del dynagem.gs? delete GSS and GST files needed by GEMSIM, and made by TABLO del year20??.sl4 delete solution files which should be made del year20??.har delete updated data which should be made tablo -sti dynagem.sti gemsim -cmf year2001.cmf gemsim -cmf year2002.cmf gemsim -cmf year2003.cmf gemsim -cmf year2004.cmf dir/od year20??.sl4
After this change, it is impossible for any job to run, unless every preceding job produced the expected output files. You can be sure that all outputs (including log files) were indeed produced during the most recent run. You could tell that the job crashed during the first year since the last command would list no solution files.
Use comments to document your BAT. Any line beginning REM (short for 'remark') is treated by Windows as a comment (ie, ignored).
By default, TABLO and GEMSIM will send thousands of lines of output to the screen. Instead, you can use the ">" redirection operator to save output to a file, or to discard it. Our BAT file becomes:
REM dynamic simulation, using input files: REM dynagem.tab dynagem.sti base2001.har and year20yy.cmf REM first, delete files we expect to produce del *.log del dynagem.gs? del year20??.sl4 del year20??.har tablo -sti dynagem.sti >tbdynagem.log gemsim -cmf year2001.cmf >NUL gemsim -cmf year2002.cmf >NUL gemsim -cmf year2003.cmf >NUL gemsim -cmf year2004.cmf >NUL dir/od year20??.sl4
Now, output from TABLO will be stored in file tbdynagem.log. We're assuming that each CMF file contains the line:
log file = yes;
meaning that log output will already be stored in files named (after the cmf file) year200?.log, so that GEMSIM screen output may safely be thrown away. The expression ">NUL" causes Windows to simply suppress the output (ie, NUL is Windows' name for the bit bucket.)
Suppose you altered year2003.cmf, so that the last 2 simulations must be run again -- and you are too impatient to run the whole BAT. You could edit the BAT to jump to a label:
REM dynamic simulation, using input files: REM dynagem.tab dynagem.sti base2001.har and year20yy.cmf goto skip jump to label "skip" ; no colon here REM first, delete files we expect to produce del *.log del dynagem.gs? del year20??.sl4 del year20??.har tablo -sti dynagem.sti >tbdynagem.log gemsim -cmf year2001.cmf >NUL gemsim -cmf year2002.cmf >NUL :skip arrive here; note that label line must begin with a colon gemsim -cmf year2003.cmf >NUL gemsim -cmf year2004.cmf >NUL dir/od year20??.sl4
This of course would be a temporary hack; it evades the output file deletion which protects us from error. Usually the goto jumps to a label in a subsequent line; however backward jumps are also possible -- allowing endless loops!
A well-written program, when it completes, informs Windows of its exit status: either errorlevel 0 (success), or errorlevel 1 (failure). The BAT can test the errorlevel, and jump according to the result. With these checks our BAT file might become:
REM dynamic simulation, using input files: REM dynagem.tab dynagem.sti base2001.har and year20yy.cmf REM first, delete files we expect to produce del *.log del dynagem.gs? del year20??.sl4 del year20??.har tablo -sti dynagem.sti >tbdynagem.log if errorlevel 1 goto error jump to "error" if any problem gemsim -cmf year2001.cmf >NUL if errorlevel 1 goto error jump to "error" if any problem gemsim -cmf year2002.cmf >NUL if errorlevel 1 goto error jump to "error" if any problem gemsim -cmf year2003.cmf >NUL if errorlevel 1 goto error jump to "error" if any problem gemsim -cmf year2004.cmf >NUL if errorlevel 1 goto error jump to "error" if any problem echo Job done OK if arrive here, all must be OK dir/od year20??.sl4 list results goto endOK finish now -- do NOT go on to next lines :error ---- GET HERE IF ANY ERROR dir/od *.log list Logs, most recent last echo PROBLEM !!!! examine most recent Log exit /b 1 exit BAT, setting errorlevel to 1 :endOK exit BAT file
Note the following:
For source-code GEMPACK, which allows you run a model-specific EXE instead of GEMSIM, our example BAT file needs minor alterations (see red comments):
REM dynamic simulation, using input files: REM dynagem.tab dynagem.sti base2001.har and year20yy.cmf REM first, delete files we expect to produce del *.log del dynagem.ax? delete obsolete AXS and AXT files del dynagem.exe delete previous EXE file del year20??.sl4 del year20??.har tablo -sti dynagem.sti >tbdynagem.log if errorlevel 1 goto error Call LTG dynagem need "call" since LTG is really LTG.BAT if errorlevel 1 goto error dynagem -cmf year2001.cmf >NUL Dynagem instead of GEMSIM if errorlevel 1 goto error dynagem -cmf year2002.cmf >NUL if errorlevel 1 goto error dynagem -cmf year2003.cmf >NUL if errorlevel 1 goto error dynagem -cmf year2004.cmf >NUL if errorlevel 1 goto error echo Job done OK dir/od year20??.sl4 goto endOK :error dir/od *.log echo PROBLEM !!!! examine most recent Log exit /b 1 exit BAT, setting errorlevel to 1 :endOK
Note the use of CALL with LTG: CALL is needed because LTG is actually a BAT; without the CALL, execution of the BAT would not resume after LTG had finished. Use CALL to make execution resume at the line following LTG.
In the examples so far, we have assumed that BAT lines are executed in order, and that each command finishes before the next one begins. However, if a BAT line launches a Windows (GUI) program, such as Excel or ViewHAR, BAT execution continues straight onto the next line, without waiting for Excel to close. You can see the same phenomenon if you type "ViewHAR" into the command-prompt: ViewHAR starts but does not prevent you typing in more commands.
If you want to make sure that Excel finishes before the next BAT line is run, you should include a BAT line like:
start/wait "C:\Program Files\Microsoft Office\Office\EXCEL.EXE" results.xls
Above note that (a) Excel is not usually on the PATH, so the actual location of Excel.exe needs to be given; and (b) the full filename contains spaces, so must be quoted. Actually, because Windows knows that XLS files are "associated" with Excel, the following simpler command would also work.
Similarly you could display an HTM file, without knowing which browser (IE or Firefox) will be chosen by Windows:
Very often we need to run "TABLO -sti xxxx" followed by "LTG xxxx", where "xxxx" is the name of a TAB file. We could create a file COMPILE.BAT which combined both operations and worked for any TAB file, as follows:
REM run TABLO and LTG for %1 model REM assumes that both %1.TAB and %1.STI exist del *.log del %1.ax? delete obsolete AXS and AXT files del %1.exe delete previous EXE file tablo -sti %1.sti >tb%1.log if errorlevel 1 goto error Call LTG %1 need "call" since LTG is really LTG.BAT if errorlevel 1 goto error echo Job done OK dir/od %1.?x? list produced AXS,AXT and EXE files goto endOK :error dir/od *.log echo PROBLEM !!!! examine most recent Log exit /b 1 exit BAT, setting errorlevel to 1 :endOK
To run this BAT you could type, for example:
Above, "oranig" is the first (indeed the only) parameter of the BAT. As each line of the BAT is run, each occurrence of "%1" is replaced by "oranig".If the BAT required more parameters, they would be represented by %2, %3 and so on (up to %9).
You could also type just:
ie, omit the ".bat". This however carries a risk -- if there is a file called compile.exe, that file will run instead of compile.bat [the PathExt environment variable controls this feature].
All sorts of utility BAT files can be created to speed your work. The next example, SNAPSHOT.BAT, (a) deletes various junk files, and (b) creates a snapshot zip of important files in the current folder. You would run it every few hours to make a "restore point" or backup. Then if, for example, you accidentally deleted an important file, a recent backup copy would be available.
REM clean up junk and back up important files del *.bak del *.log del gpxx*.* del *.slc del *.upd REM now zip up all files needed to repeat the work del snap.zip ensure no existing snap.zip zip snap *.TAB *.CMF *.BAT *.STI basedata.har put important files in snap.zip md snapshots create subfolder "snapshots" if it does not already exist move snap.zip snapshots\snap%RANDOM%.zip put snap.zip in snapshots folder with new (randomly-generated) name dir/od snapshots list snapshot zips in order of creation
We have barely scratched the surface of this huge topic -- we have not even mentioned the fascinating and powerful SET and FOR commands. However, if you followed the examples above, you have learned enough to do useful work. Below are some resources to find out more.
To find Microsoft's (scant) online help about batch files, click on the Desktop, and press F1 -- "Help and Support Centre" should appear. Then search for batch. You can also get help from the command prompt by typing a command with the "/?" option, for example type "set/?" or "echo/?".
Some more advanced GEMPACK examples may be found in Archive Item TPMH0129.
Other resources are www.ss64.com, www.dostips.com and www.robvanderwoude.com. There is a book, Windows NT Shell Scripting, by Timothy Hill. Or just Google DOS batch
are small programs to help do something that would otherwise be difficult in a BAT file. Three are included in the GEMPACK "bundle" that you can download from here. Each is intended to assist branching using the "if errorlevel" construct.
Type Later/? or TstHar/? or SetErr/? to find out more.
BAT files can be addictive ! Some people (you will find them on the internet) develop an interest that goes beyond the utilitarian. You will find sites that discuss:
You should avoid the more esoteric techniques, especially if you hope that other people can use and understand your BAT files, and that they will run on PCs with other versions of Windows.
Running GEMPACK from the command-prompt
A GTAP tutorial on processing data using BAT files
Running GEMPACK programs from another program
GEMPACK FAQ Page