China DOS Union

Batch file syntax

Batch file syntax

Files with the extension bat (under nt/2000/xp/2003 they can also be cmd) are batch files.

==== Note =======================================
.bat is a DOS batch file
.cmd is another kind of batch file for the nt-kernel command-line environment
From a broader point of view, unix shell scripts and text in other operating systems or even applications that is interpreted and executed by a shell also have very similar functions to batch files, and are likewise interpreted and executed line by line by a dedicated interpreter. A more general name for this kind of text form is scripting language. So to some extent, batch, unix shell, awk, basic, perl and other scripting languages are all the same; only their application scope and interpretation platform differ. Some applications even still use the term batch processing, but their contents and extensions are completely different from DOS batch files.
===================================

First of all, a batch file is a text file. Each line in this file is a DOS command (most of the time just like a command line we execute at the DOS prompt). You can use Edit under DOS or any text file editing tool such as Windows Notepad (notepad) to create and modify batch files.

==== Note ===================
A batch file can absolutely use non-DOS commands, and can even use ordinary data files without executable characteristics. This is due to the involvement of the new interpretation platform of the Windows system, which has made the application of batch files more and more "marginalized." So the batch processing we discuss should be limited to the DOS environment or command-line environment, otherwise many concepts and assumptions would need major changes.
========================

Second, a batch file is a simple program. You can control the flow of command execution through conditional statements (if) and flow-control statements (goto), and you can also use loop statements (for) in batch files to execute a command repeatedly. Of course, the programming ability of batch files is very limited compared with programming languages such as C, and it is also very non-standardized. The program statements of batch processing are DOS commands one by one (including internal commands and external commands), and the ability of batch processing mainly depends on the commands you use.

==== Note ==================
A batch file (batch file) can also be called a batch program (batch program). This is different from compiled languages. For the C language, files with the extension c or cpp can be called C language files or C source code, but only the exe file after compilation and linking can be called a C program. Because a batch file itself has both the readability of text and the executability of a program, the boundaries between these terms are relatively vague.
===========================

Third, every written batch file is equivalent to a DOS external command. You can put the directory it is in into your DOS search path (path) so that it can run from any location. A good habit is to create a bat or batch directory on the hard disk (for example C:BATCH), and then put all the batch files you write into that directory. Then as long as you set c:batch in path, you can run all the batch programs you wrote from any location.

==== Note =====
In a pure DOS system, executable programs can roughly be divided into five categories. In order from high to low execution priority they are: DOSKEY macro commands (resident in memory beforehand), internal commands in COMMAND.COM (loaded into memory at any time according to the memory environment), executable programs with the com extension (loaded directly into memory by command.com), executable programs with the exe extension (relocated and then loaded into memory by command.com), and batch programs with the bat extension (interpreted and analyzed by command.com, which according to their contents calls categories 2, 3, 4, and 5 of executable programs in priority order, analyzing one line and executing one line; the file itself is not loaded into memory)
============

Fourth, under DOS and Win9x/Me systems, the AUTOEXEC.BAT batch file in the root directory of drive C: is an auto-run batch file. This file runs automatically every time the system starts. You can put commands that need to be run every time the system starts into this file, such as setting the search path, loading the mouse driver and disk cache, setting system environment variables, etc. Below is an example of an autoexec.bat running under Windows 98:
@ECHO OFF
PATH C:WINDOWS;C:WINDOWSCOMMAND;C:UCDOS;COSTools;

C:SYSTOOLS;C:WINTOOLS;C:BATCH
LH SMARTDRV.EXE /X
LH DOSKEY.COM /insert
LH CTMOUSE.EXE
SET TEMP=D:TEMP
SET TMP=D:TEMP
==== Note =====
AUTOEXEC.BAT is the auto-run batch file of the DOS system, interpreted and executed by COMMAND.COM at startup;
and in the Win9x environment, not only were many other auto-run batch files such as DOSSTART.BAT and WINSTART.BAT added, but many variants such as .DOS .W40 .BAK .OLD .PWS were also added for AUTOEXEC.BAT to suit complex environments and changing needs.
==== Editor's note by willsort =============
There are many points in the following classification of commands that are worth examining. In the common commands, @ is not really a command, while dir and copy, which are also very commonly used, are not listed. And among the special commands, all of them are common commands to me. I suggest dividing the commands referenced by batch files into three categories: internal commands, external commands, and third-party programs. Among internal commands and external commands, there is another category specifically for or commonly used in batch files, which can be called "batch commands."

The following is excerpted from the MS-DOS 6.22 help document about "batch commands." Of course, some concepts and definitions in it are already a bit outdated.

Batch commands

A batch file or batch program is a text file containing several MS-DOS commands, with the extension .BAT. When the name of the batch program is entered at the command prompt, MS-DOS executes the commands in that batch program as a group.

Any command usable at the command prompt can be used in a batch program. In addition, the following MS-DOS commands are used especially in batch programs.
==========

Common commands

echo, @, call, pause, rem (small tip: use :: instead of rem) are the most commonly used commands in batch files. Let's start learning from them.

==== Note ===========
First, @ is not a command, but a special marker in DOS batch processing, used only to suppress command-line echoing. Below are some special markers you may see in DOS command lines or batch files:
CR(0D) command-line terminator
Escape(1B) ANSI escape character introducer
Space(20) commonly used parameter delimiter
Tab(09) ; = infrequently used parameter delimiters
+ COPY command file concatenation symbol
* ? file wildcards
"" string delimiter
| command pipe symbol
< > >> file redirection symbols
@ command-line echo suppression symbol
/ parameter switch introducer
: batch label introducer
% batch variable introducer

Second, :: can indeed serve as a rem comment, and it is simpler and more effective; but there are two points to note:
First, aside from ::, any line beginning with : is treated as a label in batch processing, and all content after it is ignored directly. Just to distinguish it from a normal label, it is recommended to use a label that goto cannot recognize, that is, immediately after : put a special symbol that is not alphanumeric.
Second, unlike rem, a line after :: will not be echoed during execution, regardless of whether echo on is used to turn on command-line echoing, because the command interpreter does not regard it as a valid command line. From this point of view, rem is more suitable than :: in some situations; in addition, rem can be used in config.sys files.
=====================

echo means display the characters after this command
echo off means that after this statement, all commands that run will not display the command line itself
@ is similar to echo off, but it is added at the very beginning of each command line, indicating that the command line of this line is not displayed during execution (it can only affect the current line).
call calls another batch file (if you call another batch file directly without call, then after that batch file finishes executing, you will not be able to return to the current file and execute the subsequent commands in the current file).
pause pauses batch execution when this line runs and displays the prompt Press any key to continue... on the screen, waiting for the user to press any key before continuing
rem means the characters after this command are explanatory text (comments), not executed, only for your own future reference (equivalent to comments in a program).
==== Note =====
The description here is rather confusing. It is better to quote the command-line help for each command directly for clarity

-------------------------
ECHO

When a program runs, displays or hides the text in a batch program. It can also be used to enable or disable command echoing.

When a batch program runs, MS-DOS generally displays (echoes) the commands in the batch program on the screen.
Use the ECHO command to turn this function off.

Syntax

ECHO

To use the echo command to display a command, use the following syntax:

echo

Parameters

ON|OFF
Specifies whether command echoing is enabled. To display the current ECHO setting, use the ECHO
command without parameters.

message
Specifies the text for MS-DOS to display on the screen.

-------------------

CALL

Calls another batch program from one batch program without causing the first batch program to terminate.

Syntax

CALL filename

Parameters

filename
Specifies the name and location of the batch program to call. The filename must use .BAT as the extension.


batch-parameters
Specifies the command-line information required by the batch program.

-------------------------------

PAUSE

Pauses execution of a batch program and displays a message prompting the user to press any key to continue. This command can only be used in batch
programs.

Syntax

PAUSE


REM

Adds comments to a batch file or CONFIG.SYS. REM can also be used to mask commands (in CONFIG.SYS
a semicolon ; can also be used instead of the REM command, but in a batch file it cannot replace it).

Syntax

REM

Parameters

string
Specifies the command to mask or the comment to include.
=======================

Example 1: Use edit to edit the file a.bat, enter the following content and save it as c:a.bat. After executing this batch file, the following can be done: write all files in the root directory to a.txt, start UCDOS, enter WPS, etc.

　　The content of the batch file is: 　　　　　　　 Command comments:

　　　　@echo off　　　　　　　　　　　Do not display subsequent command lines nor the current command line
　　　　dir c:*.* >a.txt　　　　　　　Write the file list of drive C to a.txt
　　　　call c:ucdosucdos.bat　　　　Call ucdos
　　　　echo 你好 　　　　　　　　　　 Display "Hello"
　　　　pause 　　　　　　　　　　　　 Pause, wait for a keypress to continue
　　　　rem 准备运行wps 　　　　　　　 Comment: prepare to run wps
　　　　cd ucdos　　　　　　　　　　　 Enter the ucdos directory
　　　　wps 　　　　　　　　　　　　　 Run wps　　

Parameters of batch files

Batch files can also use parameters like functions in the C language (equivalent to the command-line parameters of DOS commands). This requires a parameter specifier "%".

% means parameters. Parameters refer to strings added after the filename when running the batch file, separated by spaces (or Tab). Variables can be from %0 to %9. %0 represents the batch command itself, and the other parameter strings are represented in order by %1 to %9.

Example 2: There is a batch file named f.bat in the root directory of C:, with the content:
@echo off
format %1

If you execute C:>f a:
then when f.bat is executed, %1 means a:, so format %1 is equivalent to format a:, so what the above command actually executes is format a:

Example 3: There is a batch file named t.bat in the root directory of C:, with the content:
@echo off
type %1
type %2

Then run C:>t a.txt b.txt
%1 : means a.txt
%2 : means b.txt
So the above command will display the contents of the files a.txt and b.txt in sequence.

==== Note ===============
In batch files, parameters are also treated as variables, so the percent sign is likewise used as the introducer, followed by a number from 0-9 to form a parameter reference. The relationship between the reference and the parameter (for example between %1 and a: in the above text) is similar to the relationship between a variable pointer and a variable value. When we want to reference the eleventh or more parameters, we must move DOS's parameter starting pointer. The shift command is what plays the role of moving this pointer; it moves the parameter starting pointer to the next parameter, similar to pointer operations in the C language. Diagram as follows:

Initial state, cmd is the command name, which can be referenced with %0
cmd arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9 arg10
^ ^ ^ ^ ^ ^ ^ ^ ^ ^
| | | | | | | | | |
%0 %1 %2 %3 %4 %5 %6 %7 %8 %9

After 1 shift, cmd can no longer be referenced
cmd arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9 arg10
^ ^ ^ ^ ^ ^ ^ ^ ^ ^
| | | | | | | | | |
%0 %1 %2 %3 %4 %5 %6 %7 %8 %9

After 2 shifts, arg1 is also discarded, and %9 points to empty, having no reference meaning
cmd arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9 arg10
^ ^ ^ ^ ^ ^ ^ ^ ^
| | | | | | | | |
%0 %1 %2 %3 %4 %5 %6 %7 %8

Unfortunately, neither win9x nor DOS supports the reverse operation of shift. Only in the nt-kernel command-line environment does shift support the /n parameter, allowing repeated movement of the starting pointer based on the first parameter.
=================

Special commands


if goto choice for are relatively advanced commands in batch files. If you use these very skillfully, then you are an expert at batch files.


1. if is a conditional statement, used to determine whether specified conditions are met, and then decide which command to execute. There are three formats:

1. if "parameter" == "string" command to execute

If the parameter is equal to (not means not equal, same below) the specified string, then the condition is met and the command is run; otherwise the next line is run.

Example: if "%1"=="a" format a:

====

In if command-line help, the description of this point is:
IF string1==string2 command
The following points need attention here:
1. The double quotes containing the string are not required by the syntax, but are just a customary "anti-empty" character
2. string1 is not necessarily a parameter; it can also be an environment variable, loop variable, or other string constant or variable
3. command is not required by the syntax either; a space after string2 can already form a valid command line
=============================

2. if exist filename command to execute
If the specified file exists, then the condition is met and the command is run; otherwise the next line is run.

For example: if exist c:config.sys type c:config.sys
means that if the file c:config.sys exists, then display its contents.

****** Note ********
The following usage can also be used:
if exist command
device refers to devices already loaded in the DOS system. Under win98 there are usually:
AUX, PRN, CON, NUL
COM1, COM2, COM3, COM4
LPT1, LPT2, LPT3, LPT4
XMSXXXX0, EMMXXXX0
A: B: C: ...,
CLOCK$, CONFIG$, DblBuff$, IFS$HLP$
The exact contents will vary slightly depending on the hardware and software environment. When using these device names, the following three points must be ensured:
1. The device really exists (except for software-virtualized devices)
2. The device driver has been loaded (standard devices such as aux and prn are defined by the system by default)
3. The device is ready (mainly refers to a: b: ..., com1..., lpt1..., etc.)
You can use the command mem/d | find "device" /i to inspect the devices loaded in your system
Also, in the DOS system, devices are also regarded as a special kind of file, and files can also be called character devices; because both devices and files are managed by handles, and a handle is a name, similar to a file name, except that handles are not used for disk management but for memory management. So-called device loading means allocating a referable handle for it in memory.
==================================

3. if errorlevel <number> command to execute

Many DOS programs return a numeric value after running to indicate the result (or status) of the program. Through the if errorlevel command you can judge the return value of the program, and decide which command to execute according to different return values (the return values must be arranged in descending order). If the return value is equal to the specified number, then the condition is met and the command is run; otherwise the next line is run.

For example if errorlevel 2 goto x2

==== Note ===========
Arranging return values from high to low is not required, but is only customary usage when the executed command is goto. When set is used as the executed command, they are usually arranged from low to high. For example, if you need to put the return code into an environment variable, you need to use the following order:

if errorlevel 1 set el=1
if errorlevel 2 set el=2
if errorlevel 3 set el=3
if errorlevel 4 set el=4
if errorlevel 5 set el=5
...

Of course, the following loop can also be used instead; the principle is the same:
for %%e in (1 2 3 4 5 6 7 8...) do if errorlevel %%e set el=%%e

For more efficient and concise usage, you can refer to another article I wrote about obtaining errorlevel

The reason this phenomenon occurs is that the judging condition of if errorlevel when comparing return codes is not equal to, but greater than or equal to. Due to the jump characteristics of goto, sorting from low to high will cause an exit at a smaller return code; and due to the "repeated" assignment characteristic of the set command, sorting from high to low will cause a smaller return code to "overwrite" a larger return code.

In addition, although if errorlevel=<number> command is also a valid command line, it is only because command.com ignores = by treating it as a command-line separator when interpreting the command line
===========================


2. goto When a batch file runs to here, it will jump to the label specified by goto (a label is defined by : followed by a standard string). The goto statement is generally used together with if to execute different command groups according to different conditions.

For example:

goto end

:end
echo this is the end

A label is defined with ":string", and the line where the label is located is not executed.

==== Editor's note by willsort

label is often translated as "标签", but this does not have a widely established convention.

Used together, goto and : can achieve jumps in the middle of execution, and combined with if can achieve conditional branches in the execution process. Multiple if statements can achieve grouping of commands, similar to the switch case structure in C or the select case structure in Basic. Large-scale and structured command grouping can achieve the function features in high-level languages. The following is a comparison of syntactic structures between batch processing and C/Basic:

Batch C / Basic
goto&: goto&:
goto&:&if if{}&else{} / if&elseif&endif
goto&:&if... switch&case / select case
goto&:&if&set&envar... function() / function(),sub()
==================================
3. choice Using this command, the user can enter one character (for selection), and then according to the user's selection different errorlevel values are returned, which are then used with if errorlevel to run different commands according to the user's selection.

Note: the choice command is an external command provided by DOS or Windows systems. The syntax of the choice command differs slightly between versions; please use choice /? to check usage.

Command syntax for choice (this syntax is that of the choice command in Windows 2003; the command syntax of choice in other versions is generally similar):

CHOICE

Description:
This tool allows users to select one item from a list of choices and returns the index of the selected item.

Parameter list:
/C choices Specifies the list of choices to create. The default list is "YN".

/N Hides the list of choices in the prompt. The message before the prompt is displayed,
and the choices are still enabled.

/CS Allows case-sensitive choices. By default, this tool
is not case-sensitive.

/T timeout The number of seconds to pause before making the default choice. Acceptable values are from 0
to 9999. If 0 is specified, there is no pause, and the default choice
will be selected.

/D choice Specifies the default choice after nnnn seconds. The character must be in the set of choices
specified with the /C option; at the same time, nnnn must be specified with /T.

/M text Specifies the message to display before the prompt. If not specified, the tool only
displays the prompt.

/? Displays help information.

Notes:
The ERRORLEVEL environment variable is set to the key index selected from the choice set. The first listed
choice returns 1, the second returns 2, and so on. If the user presses a key that is not a valid choice,
the tool will emit a warning beep. If the tool detects an error condition, it returns an
ERRORLEVEL value of 255. If the user presses Ctrl+Break or Ctrl+C, the tool returns an ERRORLEVEL
value of 0. When using the ERRORLEVEL parameter in a batch program, arrange the parameters in
descending order.

Examples:
CHOICE /?
CHOICE /C YNC /M "Press Y to confirm, N for No, or C to cancel."
CHOICE /T 10 /C ync /CS /D y
CHOICE /C ab /M "For option 1 please choose a, for option 2 please choose b."
CHOICE /C ab /N /M "For option 1 please choose a, for option 2 please choose b."

==== Editor's note by willsort ===============================
I am listing the help for choice under win98 here for distinction

Waits for the user to choose one of a set of choices.
Waits for the user to choose one from a group of selectable characters

CHOICE choices] c,nn]

/Cchoices Specifies allowable keys. Default is YN
Specifies allowable keys (selectable characters), default is YN
/N Do not display choices and ? at end of prompt string.
Do not display the question mark and selectable characters in the prompt string
/S Treat choice keys as case sensitive.
Treat selectable characters as case-sensitive
/Tc,nn Default choice to c after nn seconds
Default to choice c after nn seconds
text Prompt string to display
Prompt string to display
ERRORLEVEL is set to offset of key user presses in choices.
ERRORLEVEL is set to the offset of the character the user presses within the set of choices
If I run the command: CHOICE /C YNC /M "Press Y to confirm, N for No, or C to cancel."
The screen will display:
Press Y to confirm, N for No, or C to cancel. ?


Example: the contents of test.bat are as follows (note: when using if errorlevel to judge return values, they should be arranged from high to low):
@echo off
choice /C dme /M "defrag,mem,end"
if errorlevel 3 goto end
if errorlevel 2 goto mem
if errorlevel 1 goto defrag

:defrag
c:dosdefrag
goto end

:mem
mem
goto end

:end
echo good bye

After this batch file runs, it will display "defrag,mem,end?" The user can choose d m e, and then the if statements make judgments according to the user's choice. d means execute the program segment with the label defrag, m means execute the program segment with the label mem, and e means execute the program segment with the label end. At the end of each program segment, goto end is used to jump the program to the end label, then the program displays good bye, and the batch file finishes running.

4. for loop command. As long as the condition is met, it will execute the same command many times.

Syntax:
Execute a specific command for each file in a set of files.

FOR %%variable IN (set) DO command

%%variable Specifies a single-letter replaceable parameter.
(set) Specifies one file or a group of files. Wildcards can be used.
command Specifies the command to execute for each file.
command-parameters
Specifies parameters or command-line switches for a specific command.

For example, a batch file has a line:
for %%c in (*.bat *.txt) do type %%c

Then this command line will display the contents of all files in the current directory whose extensions are bat and txt.

==== Editor's note by willsort =====================================================
It should be pointed out that when the string inside () is not a single or multiple filenames, it is simply treated as a string substitution. This characteristic, together with the fact that multiple strings can be embedded in (), makes it obvious that for can be regarded as a traversal loop.
Of course, in the command-line environment of the nt/2000/xp/2003 series, for has been given more features, enabling it to analyze command output or strings in files, and many switches are used to extend file substitution functions.
========================================================================

Batch file examples

1. IF-EXIST

1) First use Notepad to create a batch file test1.bat in C:, with the following content:
@echo off
IF EXIST AUTOEXEC.BAT TYPE AUTOEXEC.BAT
IF NOT EXIST AUTOEXEC.BAT ECHO AUTOEXEC.BAT does not exist

Then run it:
C:>TEST1.BAT

If AUTOEXEC.BAT exists in C:, its contents will be displayed; if it does not exist, the batch file will tell you that the file does not exist.

2) Next create another file test2.bat with the following content:
@ECHO OFF
IF EXIST %1 TYPE %1
IF NOT EXIST %1 ECHO %1 does not exist

Execute:
C:>TEST2 AUTOEXEC.BAT
The result of this command is the same as above.

Explanation:
(1) IF EXIST is used to test whether a file exists, in the format
IF EXIST command
(2) %1 in the file test2.bat is a parameter. DOS allows 9 pieces of batch parameter information to be passed to a batch file, namely %1~%9 (%0 represents the test2 command itself). This is a bit like the relationship between actual arguments and formal parameters in programming. %1 is the formal parameter, and AUTOEXEC.BAT is the actual parameter.

==== Editor's note by willsort =====================================================
DOS does not have a limitation of "allowing 9 pieces of batch parameter information" to be passed. The number of parameters is only limited by the command-line length and the processing ability of the called command. However, in a batch program, at the same moment we can only reference 10 parameters at the same time, because DOS only provides the ten parameter references %0~%9.
========================================================================

3) Going one step further, create a file named TEST3.BAT with the following content:
@echo off
IF "%1" == "A" ECHO XIAO
IF "%2" == "B" ECHO TIAN
IF "%3" == "C" ECHO XIN

If you run:
C:>TEST3 A B C
The screen will display:
XIAO
TIAN
XIN

If you run:
C:>TEST3 A B
The screen will display
XIAO
TIAN

During the execution of this command, DOS assigns an empty string to parameter %3.

2. IF-ERRORLEVEL

Create TEST4.BAT with the following content:
@ECHO OFF
XCOPY C:AUTOEXEC.BAT D:
IF ERRORLEVEL 1 ECHO File copy failed
IF ERRORLEVEL 0 ECHO File copied successfully

Then execute the file:
C:>TEST4

If the file copy succeeds, the screen will display "File copied successfully"; otherwise it will display "File copy failed."

IF ERRORLEVEL is used to test the return value of the previous DOS command. Note that it is only the return value of the immediately previous command, and the return values must be judged in descending order.
Therefore the following batch file is wrong:

@ECHO OFF
XCOPY C:AUTOEXEC.BAT D:
IF ERRORLEVEL 0 ECHO File copied successfully
IF ERRORLEVEL 1 ECHO File to copy not found
IF ERRORLEVEL 2 ECHO User aborted the copy operation with ctrl-c
IF ERRORLEVEL 3 ECHO Initialization error prevented the file copy operation
IF ERRORLEVEL 4 ECHO Disk write error during copy

No matter whether the copy succeeds or fails, the following:

File to copy not found
User aborted the copy operation with ctrl-c
Initialization error prevented the file copy operation
Disk write error during copy

will all be displayed.

Below are the return values of several common commands and what they mean:

backup
0 backup successful
1 backup file not found
2 file-sharing conflict prevented completion of backup
3 user aborted backup with ctrl-c
4 backup operation terminated due to a fatal error

diskcomp
0 disks compared identical
1 disks compared different
2 user aborted compare operation with ctrl-c
3 compare operation terminated due to a fatal error
4 initialization error aborted compare

diskcopy
0 disk copy operation successful
1 non-fatal disk read/write error
2 user ended copy operation with ctrl-c
3 disk copy aborted due to a fatal processing error
4 initialization error prevented copy operation

format
0 format successful
3 user aborted format process with ctrl-c
4 format aborted due to a fatal processing error
5 at the prompt "proceed with format（y/n）?" the user entered n to end

xcopy
0 files copied successfully
1 file to copy not found
2 user aborted copy operation with ctrl-c
4 initialization error prevented file copy operation
5 disk write error during copy

chkdsk
0 no errors found
255 one or more errors found

choice
0 user pressed ctrl+c/break
1 user pressed the first key
255 error condition detected in the command line
other the position of the valid character the user pressed in the list

defrag
0 compression of fragments successful
1 internal error occurred
2 there are no empty clusters on the disk. To run DEFRAG, there must be at least one empty cluster
3 user exited DEFRAG with Ctrl+C
4 general error occurred
5 DEFRAG encountered an error while reading a cluster
6 DEFRAG encountered an error while writing a cluster
7 space allocation error
8 memory error
9 not enough space to compress disk fragments

deltree
0 successfully deleted a directory

diskcomp
0 the two disks are identical
1 differences found
2 comparison terminated by CTRL+C
3 severe error occurred
4 initialization error occurred

find
0 search successful and at least one matching string was found
1 search successful but no matching string was found
2 an error occurred during the search

keyb
0 keyboard definition file loaded successfully
1 illegal keyboard code, character set, or syntax was used
2 keyboard definition file is bad or not found
4 error in communication between keyboard and monitor
5 requested character set not ready

move
0 successfully moved the specified file
1 an error occurred

msav /N
86 a virus was detected

replace
0 REPLACE successfully replaced or added the file
1 MS-DOS version incompatible with REPLACE
2 REPLACE cannot find the source file
3 REPLACE cannot find the source path or target path
5 cannot access the file to be replaced
8 not enough memory to execute REPLACE
11 command-line syntax error

restore
0 RESTORE successfully restored the file
1 RESTORE cannot find the file to restore
3 user pressed CTRL+C to terminate the restore process
4 RESTORE terminated due to an error

scandisk
0 ScanDisk did not detect any errors on the drive it checked
1 ScanDisk could not run because the command-line syntax was incorrect
2 ScanDisk terminated unexpectedly because memory was exhausted or an internal error occurred
3 the user caused ScanDisk to quit midway
4 while performing a surface scan, the user decided to exit early
254 ScanDisk found disk faults and corrected them all
255 ScanDisk found disk faults, but could not correct them all

setver
0 SETVER completed the task successfully
1 the user specified an invalid command switch
2 the user specified an illegal filename
3 not enough system memory to run the command
4 the user specified an illegal version number format
5 SETVER did not find the specified item in the version table
6 SETVER did not find the file SETVER.EXE
7 the user specified an illegal drive
8 the user specified too many command-line parameters
9 SETVER detected missing command-line parameters
10 while reading the SETVER.EXE file, SETVER detected an error
11 the SETVER.EXE file is damaged
12 the specified SETVER.EXE file does not support the version table
13 there is not enough space in the version table for the new item
14 while writing the SETVER.EXE file, SETVER detected an error
========================================================================

3. IF STRING1 == STRING2

Create TEST5.BAT, with the following contents:
@echo off
IF "%1" == "A" FORMAT A:

Execute:
C:>TEST5 A
Then the screen will show the content asking whether to format drive A:.

Note: to prevent the parameter from being empty, the string is usually enclosed in double quotes (or other symbols; note that reserved symbols cannot be used).
For example: if == or if %1*==A*

5. GOTO

Create TEST6.BAT with the following contents:
@ECHO OFF
IF EXIST C:AUTOEXEC.BAT GOTO _COPY
GOTO _DONE
:_COPY
COPY C:AUTOEXEC.BAT D:
:_DONE

Notes:
(1) Before the label is the ASCII colon ":"; there cannot be a space between the colon and the label.
(2) The naming rules for labels are the same as the naming rules for filenames.
(3) DOS supports labels up to eight characters long. When it cannot distinguish between two labels, it will jump to the nearest one.

==== Editor's note by willsort =====================================================
1) a label is also called a tag (label)
2) a label cannot begin with most non-alphanumeric characters, while a filename can use many of them
3) when two labels cannot be distinguished, it will jump to the label located earlier in the file
========================================================================

6. FOR

Create C:TEST7.BAT with the following contents:
@ECHO OFF
FOR %%C IN (*.BAT *.TXT *.SYS) DO TYPE %%C

Run:
C:>TEST7

After execution, the screen will display the contents of all files in the root directory of drive C: whose extensions are BAT, TXT, and SYS (excluding hidden files).

This kind of post is everywhere.

Just what I needed,
thumbs up!!

You still need to post this kind of thread? Look how many there already are in the forum.

Some people do need it too
Hehe

Although it's a repost, it's still useful for people who need it, and the summary is pretty good

An old thread
but a good one
praise for you