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████████████████████████████████████████████████████████████████ BATCH FILES FOR EFFICIENCY - GETTING THE WORK DONE ████████████████████████████████████████████████████████████████ A batch file contains within it a series of DOS commands in a list. The commands may be either DOS other special batch commands you wish the computer to perform in sequence. These operations can be DOS operations (e.g., format a disk, display the date and time, etc) or other operations which load or start another program. Another way to think about a batch file is that it takes the place of your keyboard and issues commands one after another until it reaches a conclusion. Batch files operate line by line and are read directly from the disk which makes them a little slow, but nevertheless useful and extremely flexible. Batch files can even prepare a menu system for your hard drive and spare you the expense of buying a menu program from commercial sources. Working with batch files means you are programming in the most literal sense! Each line of a batch file contains one instruction or operation which the computer is to perform. Below is a listing for a very simple batch file example. Don't worry about understanding it just yet, simply note that each instruction is a DOS command on a separate line . . . EXAMPLE BATCH FILE EXPLANATION | | date date displayed time time displayed ver DOS version displayed dir a:/p directory of a: floppy displayed with a pause The primary use of batch files is to automate sequences or instructions which you use frequently. A batch file always has the extension BAT. Example: hello.bat Each line in the batch file is a separate command and is performed AS IF you had typed in the command from your keyboard at the DOS prompt! In addition to the usual DOS commands, batch files can also contain special batch commands which allow you to build small programs. We will talk about the special batch commands a little later in this tutorial. Branching (selecting various directions or choices) and iteration (repetitions of a command) are allowed within the framework of these unique batch commands. In addition, batch files may have special parameters or inputs passed to them at the time you run the batch file from the DOS command line or prompt. Batch files are POWERFUL and can control many operations! They are also fun and easy to try. A batch file is run or started by typing the file name without the extension. This of course applies to all files ending with file extensions BAT, EXE or COM. Example: a>hello Then pressing enter or return key starts the batch file hello.bat Example: c>whoops starts the file whoops.exe To terminate or stop any batch file in progress issue the break command which uses the two key combination CONTROL-BREAK (hold down the control CTRL key then press the break key) or CONTROL-SCROLL LOCK. Let's prepare a batch file: First make sure you have a formatted disk in your disk drive and DOS is displaying a DOS prompt such as a>. We will be using the command COPY CON (copy data from the CONsole) command. Note that any ASCII (plain english) text word processor or even EDLIN on your DOS disk can be used to prepare a batch file; COPY CON is only one of several alternatives. You can use either upper or lower case to prepare batch files (capitals or small letters.) Type the following list when you have a DOS prompt such as a> and a blank formatted floppy disk in the drive to accept the batch file. copy con 1.bat (press enter) (cursor skips to new line) echo Hello there (press enter) ver (press enter) date (press enter) dir/p (press enter) ^Z (press F6 OR hold control AND Z, then press enter) When done you'll have prepared a batch file of DOS commands named 1.bat. This small file will print "hello there" then type the DOS version in use then display date and finally produce a directory listing and pause after each screenful. At this point the batch file ends and returns you to DOS. In the first line we use COPY CON to begin to prepare a batch file named 1.bat. In the last line the ^Z means end of batch file preparation - exit back to DOS. To run or execute the batch file since its name is 1.bat, just type 1 (then press enter key) at the DOS prompt. Another example batch file for you to try: copy con f.bat (press enter) cls (press enter) pause (press enter) format b: (press enter) rem all done (press enter) ^Z (press F6) then (press enter) This batch file (activated by typing f then enter) will clear the screen then prepare to format a blank disk in b: drive - you MUST have FORMAT.COM on the same disk as this batch file - remember that format is an EXTERNAL command. After the batch file has formatted the disk it prints "all done" on the screen. Ctrl-Break key combination will halt the batch file operation if you wish!. The next batch file might be used to backup wordprocessing data files which end in the file extension TXT (such as ACCOUNTS.TXT) from a source disk in the a: floppy drive to the b: floppy drive. You could name it B.BAT and when you need to backup simply put the master data disk in the a: drive and the backup disk in the b: drive and type B at the DOS prompt. We've omitted the copy con command at the top of the file and the ^Z at the end since you already know how to start and end a batch file. REM This batch file backs up files ending in TXT to backup disk ECHO READY TO BACKUP. SOURCE DISK IN A: DRIVE, TARGET IN B: ? PAUSE COPY A:*.TXT B: REM All done! One batch file can start or call another, but the original batch file cannot be returned to - you must continue on within the second batch file. If a batch file contains a typing or syntax error in any of its commands, the computer will stop execution at that point and return you to DOS. DOS remembers which disk contains the batch file and the drive it was in. If you remove the original disk, DOS will ask you to replace it so it can finish executing the batch file. Batch files execute one step at a time from the disk and NOT from RAM memory. This disk-based nature of batch files make them a little slow, but they get the work done eventually. Special batch file compiler utilities exist which speed execution of batch files. Contact the author of PC-LEARN if you are curious and want to make your batch files fly! A superlative book on batch files you might wish to investigate is MOS-DOS Batch File programming by Ronny Richardson, 1988, Wincrest Books. Remember the VDISK command in our second DOS tutorial? Many DOS experts put commonly used batch files in the virtual or RAM disk where a batch file really flies! This is one trick which can turbocharge your batch file operations. Instead of executing in slow fashion from a disk drive, the batch file is forced to run from a speed ramdisk! ████████████████████████████████████████████████████████████████ AUTOEXEC.BAT FILE BASICS - THE WAKEUP CALL TO YOUR COMPUTER ████████████████████████████████████████████████████████████████ The AUTOEXEC.BAT file starts your computer exactly the way you want. It allows you to customize the machine to your liking as the computer comes to life. You can cause the AUTOEXEC.BAT file to print a startup menu of choices, load one particular program, execute another batch file or other useful tasks. The AUTOEXEC.BAT file is the first file DOS runs after loading itself and configuring the computer. The AUTOEXEC.BAT file must be on the same disk as DOS when the computer starts. The AUTOEXEC.BAT file is a special batch file which MUST be placed in the main or root directory of a disk to function properly. An AUTOEXEC.BAT file can always be modified, enlarged, edited, or deleted later as you wish. Sometimes it is useful to have several AUTOEXEC.BAT files. Each on a different startup disk to operate different programs! An AUTOEXEC.BAT file (like all BAT or batch files) can be modified with any common word processor. You don't have to use the copy con facility each time! DOS EDLIN line editing word processor will also do. EDLIN is covered in your DOS manual. Make sure you have a formatted disk in your disk drive and DOS is displaying the usual DOS prompt when you construct a batch file. Make sure you do not accidentally over-write or destroy your current AUTOEXEC.BAT file! If necessary, rename your current AUTOEXEC.BAT file (using the rename or REN command) and make a new file while saving the old one "just in case." Never edit on your original DOS disk, work on a copy! Examine the next batch file preparation sequence: copy con AUTOEXEC.BAT (press enter) 123 (press enter) ^Z (press enter) This means (first line) create a file named AUTOEXEC.BAT as typed from the keyboard or con (console). The (second line) start program named 123. Final line end of batch file preparation - stash it on the disk. When finished you'll see a file named AUTOEXEC.BAT on your directory listing screen which contains automatic startup instructions. If this file were placed on your main DOS disk it would try to start a program such as 123.EXE if such a program existed there. You can also start the AUTOEXEC.BAT by typing autoexec and then pressing enter. To take a "peek" at the contents of an AUTOEXEC.BAT file (or any bat file) simply use the type command. Example: c>type AUTOEXEC.BAT (shows contents on your screen) Example: a>type b:AUTOEXEC.BAT Here is another AUTOEXEC.BAT file, this time from a hard drive startup sequence; it provides a higher degree of control and direction that a computer user might need for hard drive customization. copy con AUTOEXEC.BAT (press enter) path \dos;\reflex;\wp;\util;\doc;\nor;\bat (press enter) prompt $P$G (press enter) cpu n (press enter) verify on (press enter) blank (press enter) mode bw80,r (press enter) dispclk (press enter) type menu (press enter) ^Z (press F6 OR hold control AND Z, then press enter) Let's examine this more complicated AUTOEXEC.BAT file in greater detail: The first line after "copy con AUTOEXEC.BAT" establishes a path command to help DOS search every subdirectory on the hard disk (you don't have to switch around to different areas of the disk, DOS will search around for you since it now knows the various "paths" to take.) The second line alters the cursor prompt to tell you your location and subdirectory. The third line is a reference to the speed the computer will operate at and is a unique command to a particular brand of machine (cpu n means start the central processing unit chip at normal speed.) Cpu is really CPU.COM, an external file which sets the computer's processing speed. The fourth line turns on the verify function for file copying. The next line instructs the DOS mode function to switch to black and white display, 80 columns wide and shift one column to the right for alignment. Next we ask DOS to tell us the time and date. A final line instructs DOS to type to the screen a file containing an ASCII test file prepared with an ordinary word processor the menu for the monitor to display. Menu probably gives us choices of programs to one and thus calls other batch files such as 1.bat, 2.bat and so on. The ^Z of course ends the file and instructs DOS to store the file away for future use on the disk. ████████████████████████████████████████████████████████████████ BATCH FILE COMMANDS AND USE ████████████████████████████████████████████████████████████████ In addition to the normal DOS commands, batch files have their own special subcommands. These commands are: ███ REM ███ The rem command sends a message to the screen or simply to document or note a part of a batch file's operation. You should use REM extensively to document long detailed batch files so you can revise things and locate portions of the program if you decide to change the batch file later. Remarks can be up to 123 characters long. REM does not cause any operation, it merely documents what you want to say or do. Example: c>REM this is the location of menu operations In DOS 2.0 the REM command could be replaced with a period or dot, but this is not true in DOS 3.0 and above. Example: c>. this is the location of menu operations ███ PAUSE ███ Stops batch file execution on a temporary basis until you press a key. Thus you can pause a batch file and do some operation (perhaps changing a floppy disk) and then continue when you strike a key. Example: b>PAUSE (no optional message included here) Example: b>PAUSE This is an optional message, pardner! ███ ECHO ███ Turns display listing of commands on/off. It can also send a message to the screen. It is frequently turned off to remove excessive screen messages. Normally, with ECHO on, screen messages are sent to the screen which can be distracting. To suppress them use the first example. To restart the messages use the second example. To add a message with the ECHO command see example three. REM or remark command can also send a message to the screen but NOT with ECHO turned off! Example: a>ECHO OFF Example: a>ECHO ON Example: a>ECHO It's raining cats, dogs and PC's. ███ PARAMETERS AND MARKERS ████ This is NOT a batch file command like ECHO or PAUSE. Instead parameters are additional pieces of information or "modifiers" which follow DOS commands. Example: c>format b:/s In the above, format is the command while b: and /s are the parameters. Parameters modify the basic operation of a DOS command but are not required by the command to operate. A batch file can also accept parameters such as a word, filename, symbol, drive letter or any useful character or group of characters! Markers placed inside the batch file listing signify which parameter goes where. Markers are made from a percent sign (%) and a single digit between 0 and 9 for a total of ten markers available (remember, zero is a number too.) Here are the ten markers: %0 %1 %2 %3 %4 %5 %6 %7 %8 %9 Let's use an example. Pretend that DOLITTLE.BAT is on your floppy. Within its listing of commands there might be this single line: ECHO %0 %1 %2 (ECHO shows messages on the monitor) If at the DOS prompt you typed: b>DOLITTLE fancy pants (then press enter) Your screen would show the following: b>ECHO DOLITTLE fancy pants. In this case, %0 has taken on the value at the start of the DOS command which is the first word "DOLITTLE". Meanwhile %1 has become "fancy" and %2 is now pants. Looking at this another way: DOLITTLE fancy pants | | | ECHO %0 %1 %2 Let's try an example. Pretend you had a large file of word processing accounts for bills you have to pay from time to time. You need to look up bills or amounts in the file accounts.txt which is in plain ASCII (english) text from your word processor. The DOS FIND utility can search large files for specific words, strings or characters. The general format for the FIND command is: FIND "text" filename. FIND is located in the file FIND.COM on your DOS disk and must be present with the batch file to be used. A simple batch file possibly named GET.BAT could do this: ECHO searching for data . . . . FIND "%1" %2 ECHO Finished, boss Start the batch file get.bat with search data like this: a>get grocery accounts.txt (first word starts get.bat, second word is the item to search for, third item is the file to search.) As a result, you will get a report of the line where the word "grocery" is found and any other data on the same line. This could also be used to search a telephone list or list of employee names and addresses. Pretty powerful idea for such a short batch file! ███ GOTO ███ Jumps to a labeled set of commands within the batch file. The general format for the command is GOTO LABEL where LABEL is a line in the batch file which must start with a colon (:) followed by a name up to eight characters long. A simple, but useless batch file illustrates the GOTO command by looping around in circles doing the same task endlessly. Example listing for batch file: :kitty REM watch this fill your screen over and over, folks GOTO kitty This batch file will continue to print the remark line over and over since it always returns to the start. Tap Ctrl-Break to stop this silliness. The true usefulness of the GOTO command is best understood by allowing the GOTO within a batch file to transfer control elsewhere within its listing rather than to the line immediately next in sequence. You can thus cause one thing to happen (depending on a condition) or a different thing to happen: choices and different outcomes! ███ IF ███ Allows conditional operation of a command. This is a fancy way of saying you can cause a batch file to make decisions based on a logical condition or input then do something. The usual syntax of the IF command is IF CONDITION COMMAND. Let's take this apart and examine the concept. In the situation IF CONDITION COMMAND: COMMAND is any normal DOS or batch file command and CONDITION is one of three possible tests that yield true or false. Example: IF %1==w GOTO dog (we'll explain this in a bit) Example: IF %3 == 80 MODE BW80 (we'll explain this in a bit) The three possible tests are: 1. The ERRORLEVEL condition (i.e., a specific number is found). 2. The STRING COMPARISON. (i.e., two strings are equivalent or not.) 3. The FILE EXISTENCE condition. (i.e., if a file exists or not.) In true full-featured programming languages many other logical tests might be allowed, but for batch files these are these the only three tests. Let's examine the three more closely. Then illustrate with an example. 1. ERRORLEVEL is a number which tells DOS whether the last program run was successful. If so the errorlevel is zero (0) anything else above zero means unsuccessful. 2. STRING COMPARISON, the second conditional test, is always indicated in a batch file by double equals signs (==). A test is symbolically shown by the condition IF string1 == string2. Frequently used with parameters or markers such as: IF %3 == 80 MODE BW80. 3. In the final and third conditional test, FILE EXISTENCE, the usual format is IF EXIST d:filename.ext. which checks for a certain file on a certain drive. You can thus check for a certain disk or file before continuing the batch file process. Pathnames are not allowed (d:\slip\and\slide). Let's try a batch file example to illustrate the use of STRING COMPARISONS to make a choice in how the batch file does its work. Pretend you have two programs. One is a word processor whose command to start is WORD and the other is a spreadsheet whose command is LOTUS to start. If we prepared a simple batch file called 1.bat whose listing is below, we could start one or the other program by using either the command: a>1 w (to start the word processor OR a>1 s (to start the spreadsheet). The remarks (REM) in the example below give you a clue to the construction of the batch file program but are not themselves commands. The end result of this batch file is a saving of keystrokes for two programs we might start often. You'll notice we have omitted the copy con at the beginning and ^Z at the end since you already know from previous examples how to start and stop batch file preparation using those steps. The REM (remarks) in this batch file are optional and could be omitted from the real thing REM This batch file selects one of two choices based on input REM The next line turns off the screen echo to avoid screen clutter ECHO OFF REM Begin test for one of two choices REM %1 in the next lines are markers for "w" or "s" from keyboard IF %1==w GOTO dog IF %1==s GOTO cat REM Next line forces goto end if no match is made for w or s GOTO end :dog REM Next command starts word processor WORD GOTO end :cat REM Next command starts spreadsheet LOTUS GOTO end :end REM Next line switches to root directory/leave the batch file CD\ ECHO Batch file done, bye bye! ███ SHIFT ███ Re-assigns the relationship of parameters to markers. It changes their values. And it does it in a very odd way . . . Remember that there are only ten markers available to a batch file to hold the parameter values as we mentioned above. Here they are: %0 %1 %2 %3 %4 %5 %6 %7 %8 %9 However you can raise the limit of 10 parameters in a batch file using the single word SHIFT. When this command is encountered in a batch file, all the parameter and marker pairings are shifted one unit to the left. Whatever was assigned to %0 is lost. A diagram to visualize. Before a SHIFT command is issued the parameters and markers might be: %0 %1 %2 | | | dog cat computer After the SHIFT command we would see: %0 %1 %2 | | | cat computer Notice that dog is lost, %1 becomes computer and %2 is left vacant unless it takes a new parameter from %3 (if %3 had a parameter). The effects of the SHIFT command are wide ranging throughout the batch file but provide great flexibility and a range of parameters greater than ten values. ███ FOR..IN..DO ███ Allows iteration (repetition) of actions or commands. The command is similar to a FOR...NEXT...STEP loop programmers use. The command is rather subtle and could be thought of as a three part single line command. The syntax is on the next line: FOR %%Variable IN (Set) DO Command Let's look more closely at the three parts: FOR %%Variable IN (Set) DO Command ============== ======= ========== | | | part 1 part 2 part 3 Translating into english it means something like: FOR a certain batch file variable withIN a SET of filenames or commands DO a certain action which DOS can carry out. The %%VARIABLE is a one-letter variable which must have a double %% prior to the letter to distinguish it from single % markers we have seen earlier. The SET portion of the command is always in parenthesis as (SET). The SET represents filenames or DOS commands you wish the %% variable to assume while the command is executing. A space is used between entries. Pathnames are never allowed but wildcards such as *.* are acceptable. If the SET contains DOS command then only the %%VARIABLE is used. The COMMAND is a DOS command or batch subcommand. One or several of these commands will contain the %%Variable in it. Let's try an example. Pretend by you want a batch file to see the DOS version then clear the screen and finally issue the directory. We could do this with a three line batch file but FOR..IN..DO can do this in one: Example: FOR %%T IN (Ver cls Dir/P) DO %%T Notice in the above example how each DOS command is separated by a space. ? and * are not allowed within any command within the SET. Use a colon (:) instead of a space within the set when passing parameters to programs. You can issue the FOR..IN..DO batch file subcommand at the DOS prompt by dropping one of the percentage signs ( % ) on the variable. ████████████████████████████████████████████████████████████████ A BATCH FILE SUMMARY AND POP QUIZ! ████████████████████████████████████████████████████████████████ Use your imagination to construct batch files to shorten your DOS tasks. Here is the source code text of GO.BAT which used to control the old version of PC-LEARN with a batch file menu! You could use a batch file such as this to operate a menu for your hard drive! By the way, for a lengthy batch file such as this, you would probably use your word processor to prepare the batch file rather than the tedious COPY CON command method used earlier - just make sure that the final file is output as pure ASCII text; see your word processor manual for notes on this technique. The basic flow of this long batch file is to display a menu screen, wait for a keypress for the user to select and then using a label system to branch to that area of the program that views or displays a test tutorial to the screen. Menu batch file for an older version of PC-LEARN: BATCH FILE COMMAND EXPLANATION | | ECHO OFF Cause screen NOT to display each batch file command CLS Clear screen from any previous program display DRIVER1 Run driver1.com to display cover screen of PC-LEARN PAUSE Wait for keypress :TOP Label marker, serves as a "bookmark" DRIVER2 Run driver2.com, diplay main menu :START Label marker, serves as a "bookmark" DRIVER3 Run driver3.com, read keypress for menu selection ECHO ON Turn on echo to display following comment . . . REM ----- WAIT FOR A MOMENT - DISK DRIVE LOADING DATA ----- ECHO OFF Turn echo back off to quench screen clutter IF ERRORLEVEL 27 GOTO END "errorlevel" line tests keypress IF ERRORLEVEL 21 GOTO START another errorlevel test IF ERRORLEVEL 20 GOTO LABELT another error level test IF ERRORLEVEL 19 GOTO LABELS IF ERRORLEVEL 18 GOTO LABELR IF ERRORLEVEL 17 GOTO LABELQ IF ERRORLEVEL 16 GOTO LABELP IF ERRORLEVEL 15 GOTO LABELO IF ERRORLEVEL 14 GOTO LABELN IF ERRORLEVEL 13 GOTO LABELM IF ERRORLEVEL 12 GOTO LABELL IF ERRORLEVEL 11 GOTO LABELK IF ERRORLEVEL 10 GOTO LABELJ IF ERRORLEVEL 9 GOTO LABELI IF ERRORLEVEL 8 GOTO LABELH IF ERRORLEVEL 7 GOTO LABELG IF ERRORLEVEL 6 GOTO LABELF IF ERRORLEVEL 5 GOTO LABELE IF ERRORLEVEL 4 GOTO LABELD IF ERRORLEVEL 3 GOTO LABELC IF ERRORLEVEL 2 GOTO LABELB :LABELA Destination label if keypress is "A" view intro.tut Run view.com to display intro tutorial GOTO TOP Goto label "top" when done :LABELB Remaining lines similar to above view history.tut GOTO TOP :LABELC view dos1.tut GOTO TOP :LABELD view dos2.tut GOTO TOP :LABELE view batch.tut GOTO TOP :LABELF view wordp.tut GOTO TOP :LABELG view spread.tut GOTO TOP :LABELH view databs.tut GOTO TOP :LABELI view hd.tut GOTO TOP :LABELJ view displstd.tut GOTO TOP :LABELK view equipmnt.tut GOTO TOP :LABELL view bibliog.tut GOTO TOP :LABELM view usergrp.tut GOTO TOP :LABELN view glossry.tut GOTO TOP :LABELO view software.tut GOTO TOP :LABELP view modem.tut GOTO TOP :LABELQ view tips.tut GOTO TOP :LABELR view virus.tut GOTO TOP :LABELS view bonus.tut GOTO TOP :LABELT view author.tut GOTO TOP :END CLS ECHO ON REM ----- THANKS FOR USING PC-LEARN! END OF TUTORIAL SYSTEM ----- REM ----- REGISTERING PC-LEARN WILL BRING YOU THE BONUS DISK! ---- (end of PC-LEARN batch file GO.BAT example)