中国DOS联盟

2007-12-03
Why Learn DOS When There's Windows?
Because DOS is more efficient in some aspects; learning Linux, it's more convenient to use DOS for switches/routers; for remote control.

I. Introduction and Overview
1. Files and Directories
File name: file base name + suffix
File base name: 1 - 8 characters, must exist for the file name; suffix: 0 - 3 characters, optional.
Directory: Called "folder" in Windows.
When displayed with DIR, it has the mark, indicating they are directories.
2. .exe: Executable file
.com: Command file
.bat: Batch file
They are all called "executable files".
The priority of the .bat suffix file is higher than those with .exe and .com suffixes.
3. Internal and External DOS Commands
Internal commands are directly loaded into memory by command.com when the system starts and can be used directly.
In other words, internal commands exist in the command.com file.
External commands are independent files existing on the disk and can be loaded into memory for execution when needed.
4. . and .. and \
. : Current directory
.. : The upper-level directory of the current directory, also called "parent directory"
\ : Root directory.
5. Dir Command
When the current directory has . and .., when using the dir command to display the current directory information, they are considered as a file, just with a size of zero.
6. DOS Boot Sequence
Boot -> IO.SYS -> MSDOS.SYS -> CONFIG.SYS -> COMMAND.COM -> Autoexec.bat
Among them, IO.SYS, MSDOS.SYS, and COMMAND.COM are essential for the startup of the DOS system.
io.sys: Input/output processing program
Msdos.sys: File processing program
Command.com: Command processing program
New Explanation:
For DOS, when the hard disk boots, the INT19 interrupt first reads the "hard disk MBR". After reading, it is loaded into memory at 0000:007c, and then INT19 also jumps to 0000:007c in memory. At this time, the control right is still INT19. Then, a "program" in the MBR will look for the "bootable partition". After finding it, the bootable partition is loaded into 0000:007c. Then the MBR program will jump to the address 0000:007c, and the system starts to boot.
The main boot sector is: cylinder 0, head 0, sector 1
Then comes the FAT (File Allocation Table)
Supplementary (2007-12-10)
. DOS: disk operating system, single-user single-task OS.
Cold boot: When starting the computer, turn on the monitor power -> host power, and the shutdown is in the reverse order.
Warm boot: When the system is started, press the CTRL+ALT+DEL key combination to start the system again.
Difference between the two: Whether to skip some hardware detection processes such as memory detection, and other running processes are the same.
. Common Reserved Names in DOS
CON: Keyboard/display
NUL: Empty device or virtual device
AUX/COM1: First serial communication interface
COM2\COM3\COM4: 2nd, 3rd, 4th serial ports
LPT1\PRN: First parallel interface
. A batch file can be understood as "a DOS command".
. Why Not Name a Batch File as an "Internal Command or External Command" of DOS?
Answer: If it has the same name as an internal command, then the internal command has a higher priority than the batch, and the batch file cannot be executed;
If it has the same name as an external command, it depends on "whether the external command or the batch file is found first". The one found first is executed first. Therefore, it is recommended to avoid naming batches the same as internal and external commands of DOS.
. How to Create a Batch File in DOS?
a. copy con the batch file to be created
b. edit the batch file to be created
. Also can use
Pause the information to be displayed, similar to echo the information to be displayed
. How to Make a "Batch File" Beep? (Relying on the built-in speaker of the computer)
In DOS, use edit beep.bat, then enter the editing page, first enter Pause, then enter a space, then hold down the CTRL key, press the "P" key, release the CTRL key, then hold down the CTRL key, press "G", and a "beep control character" can be generated.
It can also be done by holding down the CTRL key and pressing "P" and "G" keys successively.
In fact, echo can also achieve the same effect, but it is troublesome to input the control character in the text. It is a good way to edit the batch file in DOS, input the control character and save it, then return to Windows to edit.

II. Introduction to DOS Commands
1. Dir
Displays the current directory information but does not include system and hidden files.
dir /p: Display information in pages (p is the abbreviation of page, that is, display screen by page)
dir/w: Display information in a wide list, without file size and creation date
dir/d: Similar to dir/w display mode
dir/b: Only display file names, directory names are also displayed in the form of file names, and the mark of directory names is not displayed (a concise display)
dir /l: Display files and directories in lowercase letters
dir /a: Display files with specified attributes, for example: dir /a:r displays all files with read-only attributes in the current directory
Example: dir /a:d means only display directory information
Example: To find files of a specified date, dir|find "2007-12-04", pay attention to the writing format of the date to match the local date display
Example: To find files in multi-level directories, use the parameter /s, such as dir temp /s. If there is a temp directory under the current directory and there is a temp directory under temp, the execution result is to list all files in the last-level temp directory
REM
dir/? to see help, find that the : after a is optional, but if : is not used, the message "The volume of the current drive has no label, and the file is not found" will be displayed.
Why does it work without :? I made a mistake myself!
Dir /a:-r: Display all files with non-read-only attributes in the current directory
- : Represents the "prefix of no".
REM

Dir /o: Display information in a classified way, such as file size, alphabetical order, etc. For example: dir /o:s means display information according to file size; dir /o:n displays information according to alphabetical order
Dir /n: Display in "long file list mode, file name on the rightmost side"
Dir /c: Similar to dir/n
Dir/x: Display files not in the 8dot3 naming rule
Example: dir >test.txt means import the result of the dir command into a text file
2. Cd
Change directory
Note: If the following command is used on the C drive
c:\>cd e:\test
The result is still at c:\>, but it is transferred to the D drive, and the current directory of the D drive is d:\>test>. I encountered the above problem when using at to regularly delete files in a certain directory.
Example:
@echo off
c:
rem At that time, I forgot to go to c:, and as a result, many files on the disk where the batch file was located were deleted, including the batch file itself
rem Making the at task unable to execute
cd "C:\Documents and Settings\All Users\Application Data\Symantec\Symantec AntiVirus Corporate Edition\7.5\Logs"
echo y | del *.*
Cd .. means go back to the upper-level directory
Cd\ means go back to the root directory
Cd /d parameter /d means change both the current directory and the current drive
3. Copy
The function is to copy and move, but cannot copy subdirectories in the directory
Example: Merge two text files 1.txt and 2.txt into 3.txt
Copy /a 1.txt+2.txt 3.txt
REM Merge these two files according to ASCII code
Copy /b 1.txt+2.txt 3.txt
REM Merge these two files according to binary code
Parameters /a and /b cannot be used together. Among them, /a can only merge plain text files, and /b can merge in both text and binary ways
Example: Encrypt a file
copy /b test.jpg+1.txt 2.jpg
REM test.jpg and 1.txt become a file 2.jpg, so the text information is encrypted. To view this information, you can use the ultraedit software to view
REM Remember, the document to be encrypted must be placed on the right side of the + sign
4. Xcopy
Can copy non-empty subdirectories in the directory to other places, but need to use the parameter /s
/e must be used with parameter /s, indicating that not only subdirectories can be copied, but also empty directories can be copied

/v Verify after copying
5. Del
Delete
Del *.* is a very dangerous command
Example: del /f Force delete read-only files Del/a Delete files with specified attributes
6. ren
Rename
7. type
Can only display the content of one file at a time
8. Format and unformat
The available space of the formatted disk is equal to the total space of the disk, indicating that the disk performance is good
Format /u means unconditional formatting, at this time unformat is invalid
Example: Echo y|formant a:
Unformat drive letter means restore the formatted disk
unformat /l means list the recoverable file list
9. Md and Rd
Create a new directory
Example: Create multiple directories at the same time
md c:\1 d:\2 e:\3 is equivalent to md c:\1;d:\2
Delete the directory. The directory to be deleted cannot have subdirectories and files. If you want to do this, you can use
Rd /s
Example: Create an encrypted directory and how to view and delete it
md test..\
This creates an "encrypted" folder, which cannot be opened by double-clicking
It can be viewed through "Run" in the Start menu or the address bar in Explorer by entering its "complete path"
Delete it through rd /s /q
Thought: If the "encrypted" folder established is combined with the method of hiding attributes including registry hiding, a relatively private space can be established.
Approximate location of the registry: MACHINE\SOFTWARE\WINDOWNS\CURRENTVERSION\EXPLORER\ACVANCED\FOLEDR\SHWOALL\CHECKEDVALUE's value
10. Deltree
Delete the directory tree, and it deletes non-empty directories without hesitation
Deltree *.* is a very dangerous command
11. Mem
Memory
12. Chkdsk
Checkdisk
13. Sys
C:\>sys a: is equivalent to format a:/s, both are to make a bootable disk
If you copy a DOS bootable disk, the two files io.sys and msdos.sys may not be copied to the frontmost track of the disk
14. Cls
Clear screen
15. More
Display in pages
16. Move
Example: @echo off
Cd c:\test
Move c:*.* a:
REM
Note that there is no "\" between the 3rd line "c: and *.*", which means to copy all files in the current directory, that is, the test directory, to the A drive.
17. Help
As its name implies
18. Attrib
Attribute
Example: Set all files and subdirectories (including the directory itself) in the c:\test directory to "read-only" attribute
Attrib +r c:\test /s /d
/s: Indicates to operate on subdirectories
/d: Indicates to operate on directories, which can be simply understood as directory
Example: Set all files and subdirectories (excluding the directory itself) in the c:\test directory to "read-only" attribute
Attrib +r c:\test\*.* /s /d
19. Time and date
Date /t: No need to input a new time
Echo+|date|find "current date"
Echo+|time|find "current time"
Example: A batch file can be written to record the time usage of the machine
echo+|date/t>test.txt
echo+|time/t>>test.txt
20. Lable
21. Defrag
Defragment the disk
22. Doskey
Establish and call DOS macro commands
Example: doskey d=deltree, then executing d is equivalent to executing the deltree command
Example: If a lot of commands are input in CMD and you need to use these commands again without repeating input, you can use doskey. The specific operation (in CMD): doskey /h (h is history) is to view the commands that have been used in CMD before, and they can be called again through the F9 key to call their cache table, or the up and down arrows or PaUp and PaDn keys can be used to operate. If you want to clear them, you can use doskey /reinstall.
23. Fdisk
Fdisk /mbr: Re-establish the DOS main boot record
24. Memmaker
Memory optimization command
25. Emm386
Extended memory management
26. Lh or loadhigh
Load the program into the upper memory
27. Msd
System detection
Cannot be used directly
28. Undelete
Before using this command, you need to use the lock command to remove the restriction that the hard disk directory area cannot be modified
Undelete /all: Restore all del files without asking
Undelete /list: List the recoverable file list
29. Path
Example: path c:\test
If a command is executed in the current directory and it does not exist, it will continue to look for the command in the path-set path, and execute it if it exists
30. Prompt
Set the prompt, which is the common c:\> we see. c: indicates that the current drive letter is C drive, \ indicates the root directory, and > separates the prompt from the command to be input.
It can be changed according to needs
31. Backup and restore
Backup and restore
Restort /s: Restore subdirectories to the specified directory
32. Edit
Can only edit text files. If the edited file exists, it will be edited. If it does not exist, it will be temporarily created and enter the editing state. If saved, the file will be established on the disk
33. Set
Set variables. Enter the set command directly in CMD, and most system variables will be listed
Example: set path=c:\test is equivalent to path c:\test
Example: Manually input variable value
set /p a= Please input your choice
REM In the pure DOS environment, the /p parameter does not exist, and this statement is naturally not good!
REM You can define a variable similar to a system variable (a variable that still exists after restarting the machine) through the setx command. However, this command does not exist in the XP system, but exists in 2003. Format: setx variable assignment
Set /a var=
REM Arithmetic operation on variables
Example: set /a var+=1
Set %path:str1=str2%
REM Replace str1 with str2
Example: @echo off
set var= zgk.com
Echo Display the original value of var
echo %var%
pause
set a=%var: =%
rem The space in the original variable is replaced
echo Display the value of the replaced var
echo %a%
set b=%var:.=%
echo %b%
rem The dot "." in the original variable is replaced
pause
set %path:~10,5%
REM Intercept the specified number of columns of the variable
Example: @echo off
Set var=zgk.com
Echo %var%
Set b=%var:~2,3%
rem Intercept the first 2 columns of the specified variable var, that is, start reading 3 characters from the 3rd column and assign them to the new variable b, rem then b=k.o
Echo %b%
Pause
Set %path:~-10%
Example: @echo off
set var=zgk.com
Echo %var%
Set b=%var:~-3%
rem Take 3 columns from the back of the specified variable var and assign them to the new variable b, then b=com
Echo %b%
Set c=%var:~3%
rem Intercept the first 3 columns of the specified variable var from the beginning, that is, assign all variables after the 4th column of var to c, rem then c=.com
Echo %c%
pause
Set %path:~0,-2%
Example: @echo off
set var=zgk.com
Echo %var%
Set b=%var:~-3%
rem Take 3 columns from the back of the specified variable var and assign them to the new variable b, then b=com
Echo %b%
Set c=%var:~0,-2%
rem Remove 2 columns from the var from the back, then assign var to c, then c=zgk.c
Echo %c%
pause

34. Smartdrv
Set disk cache
35. Append
Set non-executable file path
Example: There is no test.txt in the current directory, and there is in c:\
append c:\ is similar to the path command
36. Debug
Debug file name
37. Diskcomp
Compare the contents of two floppy disks
38. Expand
Unzip command
Expand original compressed file path destination
39. Fc
Compare the contents of two files
Example: fc /c test1.txt test2.txt
rem /c Compare case-insensitively
40. Fasthelp
Quick help
Not available in the XP system
Fashhelp command is equivalent to command/?
41. Qbasic
Start the basic integrated environment
42. Setver
Set version, and can also view the versions of winword and excel
The common syntax in config.sys: device=setver.exe
REM
When device=setver is not added in config.sys, the versions of winword and excel can still be seen. Why can't anything be seen after adding it? There is no error message
REM
43. Share
44. Subst
Replace a certain drive letter with a specified path
Example: subst a: c:\test means replace the A drive with the test directory under the C drive
Subst a: /d means delete the replacement
45. Tree
Display the structure of all subdirectories under the current directory or specified directory, but does not display file names
/f (file): Display the directory and the file names under the directory at the same time
Tree /a: Display the directory tree in ASCII code
Example: To find the number of test.txt in the c:\test directory
tree /f c:\test | find /c /I "test.txt"
If there are too many files exceeding the buffer size, you can use: tree /f |more
46. Vsafe
Virus protection program, not tried!!!!!
47. Ver
View the DOS version number
48. Vol
View the volume label of the disk
49. Ctty
Change the input and output device of the control
Example: ctty aux means set aux as the input and output device
50. Recover
Overwrite the disk
51. Replace
Example: replace c:\test1.txt d:\test2.txt /r
Even if test2.txt has the read-only attribute, it will be replaced
Example: replace d:\a.txt d:\backup /s /p /u
/s: Replace all files with the same name in D:\backup and its subdirectories with D:\a.txt
/p: Confirm before replacing
/u: (update), check the modification time of the source file and the target file before replacing. If the former is newer, it will not be replaced
Example: @echo off
cd %1
for %%i in (*.%3) do if not exist "%2%%i" copy %%i "%2" /y
replace *.%3 "%2" /u
Execute filesyn.bat d:\ e:\ txt
52. at
Customize scheduled tasks (the scheduled tasks customized by this command run in the background, while the tasks customized by "Task Scheduler" in Windows run in the foreground). The main difference between the two is that the at command can only view the scheduled tasks customized by the at command itself, while "Task Scheduler" in the control panel can view it and the tasks customized by the at command; both rely on the task scheduler service. If this service is stopped, running the tasks in "Task Scheduler" can start this service, but the tasks customized by the at command cannot.
Example: Set the task customized by at to run in the foreground
at 16:30 /interactive c:\test.bat
/interactive can make the task run in the foreground
Example: Run a program at a specified time
At 16:00 c:\test.bat
:: Run test.bat at 16:00
Example: Run a task at 15
At 16:30 /every:15 c:\test.bat
:: Run at 16:30 on the 15th of each month
At 16:30 /next:15 c:\test.bat
:: Run at 16:30 on the 15th of next month
At 16:30 /every:Thursday c:\test.bat
:: Run at 16:30 every Thursday
Example: Delete a task
At 2 /delete /yes
:: Delete the scheduled task with task ID 2, /yes means no need to confirm when deleting the task
Example: Delete all tasks
At /delete
:: Not entering any ID means clear all scheduled tasks
53. shutdows
Shutdown /s /t time /f
/s Specify the shutdown operation
/t How long to shut down after, such as /t 6, shut down after 6 seconds
/f Force shutdown, regardless of what program is running
Example: Run a program on a specified computer
At \\computername 16:30 c:\test.bat
54. find
Standard format find "string to find" text file to be searched
Example: Find the nihao string in test.txt
find "nihao" test.txt
Find /c "nihao" test.txt
:: /c (count) Count the number of times nihao appears in test.txt
Find /n "nihao" test.txt
:: /n (number) Count the lines where all nihao are located
Find /i "nihao" test.txt
:: /i (ignore) Ignore case
Find /v "nihao" test.txt
:: /v Find the content that does not contain the nihao string
55. Shift
Increase the number of parameters in the batch
56. Systeminfo
This command is useful if you need a batch to display system information.
57. Ntsd
Force close process command, for example: ntsd –c q –pn notepad.exe
58. Create a hidden user
Previously mastered the usage of the registry:
1. Use net to create a new user; 2. Export the name item under SAM in the registry; 3. Delete the newly created user; 4. Import the exported registry
New method: net user zgktest$ /add, at this time, the newly created user cannot be viewed with net user; add a comment to the newly created user: net user zgktest$ /comment:"comment content"
59. Sfc
Scan the integrity of protected system files
/scannow: Immediately scan all protected system files and automatically repair if there are modifications.
/verifyonly: Only scan and not repair
/verifyfile: Only scan the specified file and not repair
59. Taskkill
Terminate the process
/f Force terminate
/im Specify the image name of the process to terminate
Example: taskkill /f /im ctfmon.exe /im notepad.exe

III. Introduction to Batch Commands
1. Echo on/off
Turn on or off echo
echo off means not to display all command lines after it
Echo display information
Echo y|format a: means pass the parameter y
Echo n|format a:
The following are special ways to echo empty lines
Echo.
Echo+
Echo;
Example: echo nihao
@echo nihao
Pause
Execution result:
echo nihao rem Display the command line itself
nihao rem Display the execution result of the 1st command line
nihao rem Display the execution result of the 2nd command line
2. @
Do not display the command line itself
3. Call
Call another batch or file in a batch file
Example: Call 2.bat in 1.bat
1.bat
@echo off
Echo this is 1.bat
Call 2.bat
:: At this time, using command /c 2.bat instead of call 2.bat is not okay. If there are Chinese characters in 1.bat or 2.bat, a bunch of garbled characters will be displayed
:: Using start 2.bat instead of call 2.bat, it will not return to 1.bat after execution.
Echo 2.bat end,back to 1.bat
4. Pause
Pause by pressing any key
5. Goto label and :label used together
Note that there are requirements for naming the label. If there are multiple labels in the batch, the first eight letters of the label name cannot be exactly the same, because COMMAND only recognizes the first eight. If the names are the same, the second label will never be executed.
6. Rem
Comment, equivalent to :: and /* */
7. %
Parameter identifier
Parameters refer to the strings added after the file name when running the batch file, ranging from %0~%9. %0 represents the file itself, and the strings are from %1~%9
8. If
Conditional judgment statement
If (not) /i "string1"="string2" command to be executed
/I: Indicates case-insensitive judgment
Example: @echo off
Set /p var1= please input
Set /p var2= please input
If "%var1%"=="%var2%" (echo variables are equal) else echo variables are not equal
:: The variables var1 and var2 use double quotes to compare spaces in the variables. For example, var1=a, var2=a. Without double quotes, they are equal and (echo variables are equal) is executed. With double quotes, (else echo variables are not equal) command is executed
pause
If (not) exist file command to be executed
Example: if exist c:\test1.txt (echo test1.txt exists) else echo test1.txt does not exist
If (not) errorlevel number command to be executed
Example: @echo off
Set /p commandname=Please input the command to be tested whether it exists
If errorlever==0 (echo command executed successfully) else echo command did not execute successfully
:: Once made a mistake that errorlever and 0 were forgotten to be = =, and there was no space between echo and the displayed information
pause
Example: @echo off
if not exist d:\myfolder\nul md d:\myfolder
if not exist d:\myfolder\word\nul md d:\myfolder\word
REM In the win98 system, the if statement cannot detect the existence of the directory, but can detect the empty device, so to ensure the normal operation of the script, nul is used.
If defined xxx command: Judge whether xxx is a defined variable
Example: @echo off
Set var=123
If defined var (echo var is a defined variable) else echo not defined
pause
If defined %var% (echo %var% is a defined variable) else echo %var% is not defined
:: Judge whether the value of var is a variable
pause
Set 123=456
If defined 123 (echo 123 is a defined variable) else echo not defined
pause

9. Choice
Choice /c: Parameters indicate the characters that can be input, replaced by set /p, which is rarely used now
10. For
Loop command
FOR in (collection) DO
/d Only effective for directory operations, ineffective for files
Example: @echo off
for /d /r %%i in (*) do @echo %%i
:: List all unhidden directories in the current directory, and do not operate on files
pause
/r Recursive (that is, operate on the current directory, and all subdirectories under it are also operated)
Example: @echo off
for /d /r %%i in (*) do @echo %%i
:: List all unhidden directories in the current directory and its subdirectories, and do not operate on files
pause
/l Iterate over the numerical range
Example: @echo off
for /l %%i in (1,1,5) do @echo %%i
pause
/f Read each line of content in the text and assign it to a variable or return the execution result of the command to a variable (very commonly used)
Example: There is a text test.txt with the content:
Name Relationship
; Display the corresponding relationship
Zhang Yi Labor
De Employer
@echo off
for /f "eol=; tokens=1,2 delims= " %%a in (c:\test.txt) do @echo %%a %%b
:: Read the content of the text and assign it to the variable %%a, then display the two columns of content in the text. The line with a semicolon is not displayed
:: eol=; means ignore the line starting with semicolon ;, even if this parameter is not written, it is executed by default
:: tokens=1,2 means print/display the content of the 1st and 2nd columns of the text
:: delims= means use space as the delimiter
Pause
Example: @echo off
for /f "eol=; tokens=1,2 delims= " %%a in ('net user') do @echo %%a %%b
~I means delete the quotes
Delete the quotes at the beginning and end
Delete the quotes at the beginning
The quotes at the end and in the middle are not deleted
Example: There is a test.txt document with the following content:
"afds"
"daf
Dfs"
Afd"dfa
Execute the following code
@echo off
for /f %%a in (c:\test.txt) do @echo %%~a
pause
The result is as follows:
afds
daf
Dfs”
Afd”dfa
%~fi means expand %i to a fully qualified path
Example: @echo off
for /f %%i in ('dir /b') do @echo %%~fi
pause
%~di means expand %i to a drive letter
%~pi means expand %i to the path
%~ni means expand %i to the file name
%~xi means expand %i to the file suffix
%~si means expand %i to the short name of the file
Example: @echo off
for /f %%i in ('dir /b') do @echo %%~si
pause
If there is documents and setting in the root directory, only the short name of documents will be displayed
%~ai means expand %i to the file attribute
%~ti means expand %i to the size and date of the file
%~zi means expand %i to the size of the file
%~$path:I means search for the specified file in the specified path
Example: @echo off
for /f "delims=" %%i in ("ping.exe") do @echo %%~$path:i
:: Once made a mistake, use double quotes instead of single quotes in the brackets
pause
11.,
Equivalent to space
Example: Executing dirc: in CMD will have an error message, using dir,c: will not
12. " "
Delimiter, often used to delimit "directories with spaces"
Example: Executing dir c:\documents and setting in CMD will have an error message, using dir "c:\document and setting" will not
13. ^
Escape character, cancel the function of special symbols
Example: If you want to write the > special symbol into the text file
echo > >test.txt is wrong
Echo ^> >test.txt is correct, canceling the output redirection function of the > special symbol
14. &
Command connection character, regardless of whether the command before & is executed correctly, the command after it will be executed in sequence
15. &&
Command connection character, only if the command before && is executed correctly, the command after it will be executed
16. ||
Command connection character, only if the command before || is executed incorrectly, the command after it will be executed
17. |
Pipe command
Take the output result of the previous command as the input of the next command
18. >
Output redirection command
Write the output result of the previous command to the device behind, and the content of the device behind is overwritten
19. >>
Output redirection command
Write the output result of the previous command to the device behind, and the content of the device behind is not overwritten
20. <
Output redirection command
Take the specified content of the device behind as the input of the previous device
21. * and?
Wildcards
* represents any number of characters
? represents any one character
22. Concept understanding: Variable expansion and delayed variable expansion
Variable expansion: In the execution of the batch, the process of replacing the variable name with the value of the variable.
Delayed variable expansion (using the flag setlocal enabledelayedexpansion)
Example: @echo off
for /l %%i in (1,1,5) do (
set var=%%i
echo %var%
)
Pause
:: Code interpretation, the execution result of this code segment shows "5 echo are in the off state"
:: Why?
:: Because when CMD executes the batch, it first reads each command line into memory for matching
:: Matching means checking whether there is a syntax error in the command line, not executing the command line
:: The red code is one command line
:: The variable var is first matched and cannot be executed, so at this time var has not been assigned and is empty
Example: @echo off
setlocal enabledelayedexpansion
for /l %%i in (1,1,5) do (
set var=%%i
echo !var!
)
Pause
:: Code interpretation, the execution result of this code segment shows "1 2 3 4 5 in the form of a sequence"
:: Why does this code segment execute correctly?
:: Because it uses "delayed environment variable expansion"
:: Variables in delayed environment variable expansion use "! !" instead of "% %"
:: The purpose of using delayed environment variable expansion is to execute the command line once first and then match
:: Therefore, the variable var is first assigned to 1, and then the command line is matched
Similarly:
set var=test & echo %var% will have an error message: echo is in the off state
setlocal enabledelayedexpansion
set var=test & echo !var! is executed correctly
23. ;
When the commands are the same, different targets can be separated
Example: dir c:\;d:\;e:\ is equivalent to dir c:\ dir d:\ dir e:\

Supplementary:
autoexec.bat: Batch file that runs automatically when the computer starts
winstart.bat: Batch file that runs automatically when entering the Windows state
Dosstart.bat: Batch file that runs automatically when restarting into MS-DOS under Windows
Difference: The execution time periods are different

IV. Skill Collection
1. *.* can be replaced by.
Del *.* equ del .
2. To shield the display information of the command regardless of whether the command is executed correctly, redirect the command to the empty device NUL
Example: dir >nul 2>nul
3. Add content to the text
Type con >> text name REM Tested, press F6 key or CTRL+Z to stop input
Type con >filename equ copy con filename
type nul>filename means to clear the content of the file, but the attribute of filename cannot be read-only and hidden
4.指法练习 in DOS
Copy con nul
5. Regedit /e
Export the registry, for example: regedit /e test, export the registry database to the file test.reg
Import the registry, for example: regedit/c test.reg, import test.reg into the registry
Example: regedit test.dat, import test.dat into the registry
6. In "Run" or CMD, directly run "hh ntcmds.chm", which will start the "Command Line Reference" window, which is convenient for self-study of DOS commands
7. 2>nul
2 represents the error message handle
8. Make programs execute one after another
start /w first program
start second program
9. View the list of users connected to the local machine
Net session
Clear the user temp already connected to the local
Net session \\temp /delete
10. In the subnet, cannot ping the gateway, but can ping other machines normally
Solution idea: Obtain the correct MAC address of the gateway, then execute
arp -a gateway IP gateway MAC address
11. Create a new file
type nul>new.txt
Example: Summary of methods to create a batch file
a. type nul>test.bat (test.bat is empty, need to enter content to edit)
b. copy con test.bat
c. echo dir c:>test.bat
echo dir d:>>test.bat
d. edit test.bat
edlin test.bat
e. Create a text file under Windows and then change the extension (need to enter content to edit)
12. Command prompt is prohibited
Solution idea: reg delete HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows /f >nul
13. How to understand the error message "bad command or filename" when the batch execution encounters it?
Command error;
The command is correct, but it is not in the current directory and the search path set by PATH;
There are characters that COMMAND cannot interpret in the batch file content.
14. When writing a menu with a batch, do not use special symbols, such as: |, which will cause ambiguity and errors.
15. To chat with others on QQ, you can refer to the following code: Set/p qq=Please input the QQ number you want to chat with him/her (then press enter):
start tencent://Message/?Uin=%qq%
16. How to add an empty line in a batch
@echo off
echo first^

echo second
rem ^ is an escape character, which can escape the empty line. In fact, I don't understand it very well, but this method works?
17. How to call a vbs file in a batch (not tested)
start "" a.vbs or start c:\a.vbs
How to install an inf file in a batch (view relevant content in "Tools" "Folder Options" "File Types" Advanced under "Edit")
rundll32.exe setupapi,InstallHinfSection DefaultInstall 132 c:\b.inf
18. If the hard disk is locked with Cacls, the solution
Cacls D: /t /c /g dfdgdfghfh:f rem Unlock the D drive
19. Set the operation of the local "user account"
control userpasswords2

V. Taking Things Out of Context
1. @echo msgbox "Download completed",4096 >> e:\test.vbs
start e:\test.vbs
REM The meaning of 4096 is: System mode: All applications are suspended before the user responds to the message box
2. Add a pop-up window in a batch
a、Msg %username% /time:5 “hello,zgk”
REM Requires the TermService service support; /time:5 means the pop-up window stays for 5 seconds; “hello,zgk” means the content of the pop-up window.
b、net send %computername% “Content displayed in the pop-up window” >nul
REM Requires the message messenger service support
c、Use the built-in mshta program of the system
Use the msgbox function in vbscript to display
mshta vbscrip:msgbox(“Specific content displayed in the pop-up window”,64,”Title of the pop-up window”)(windows.close)
REM 64 means the pop-up window stays for 64 seconds, and windows.close means close the window after staying for 64 seconds
d、Use the popup function of vbscript
mshta vbscript:CreateObject("Wscript.Shell").popup("Content displayed in the window",7,"Title of the window",64)(window.close)
e、mshta javascript:window.alert("Warning window information");window.close()
f、Use the popup function of javascript
mshta "javascript:new ActiveXObject('WScript.Shell').popup('Hello,lxmxn',7,'batch script',64);window.close();"
g、Use the confirm function of javascript
mshta javascript:confirm("ha");window.close()
3. Code that continuously pops up windows
@echo off
Start notepad.exe
%0
Rem Tried it, it's really fierce, only restart the machine
4. Set the number of loop times to start a program or command
@echo off
:loop
If not exist c:\test.txt echo. >c:\test.txt &goto err1
If not exist c:\test1.txt echo. >c:\test1.txt &goto err1
If not exist c:\test2.txt echo. >c:\test2.txt &goto err1
If not exist c:\test3.txt echo. >c:\test3.txt &goto err1
:err1
Start notepad.exe
Goto loop
Rem In fact, it can be realized by other methods, just for learning!
5. Batch to record the login time of the computer
@echo off
Date /t >record.txt
Time /t >>record.txt
Attrib +s +h record.txt
Attrib +s +h record.bat
Finally, add record.bat to the following position in the registry:

"Userinit"="C:\\WINDOWS\\system32\\userinit.exe,record.bat,"
Note: Write according to the actual path of record.bat. Remember, the comma, after it cannot be omitted!
9. Hide the "flashing CMD window screen" when the batch file runs
Method 1: Use JS code
new ActiveXObject('WScript.Shell').Run('cmd /c hidden.bat',0);
Method 2: Use VB code
Set ws = CreateObject("Wscript.Shell")
ws.run "cmd /c felix.bat",vbhide
Method 3: Use VB code
CreateObject("WScript.Shell").Run "cmd /c felix.bat",0
10. Copy a certain file to all directories including subdirectories on a certain disk
@echo off
for /r D: %%i in (.) do copy /y 01.txt "%%i"
pause
REM Copy 01.txt to all directories under the D drive
11. How to clean up garbage files more cleanly
Pay attention to directories such as cookies, temp, tempor~1, history and win386.swp and registry information
12. Script code to run the program in quiet mode
On Error Resume Next
set wshshell=createobject("wscript.shell")
a=wshshell.run ("file name",0)
rem The file name is the program to be run, and 0 means the program does not display the running window when it runs
13. Batch code to delete garbage files such as found.001/found.002, which is good!
for %%a in (c d e f g) do (
for /r %%a:\ %%i in (FOUND.00*) do (rd /s /q %%i >nul 2>nul)
)
14. Batch code to clear duplicate lines
@echo off
for /f "delims=" %%i in (a.txt) do (
findstr /c:"%%i" b.txt 2>nul||echo %%i>>b.txt
)
Pause
rem Why can it be realized?
rem For example, the content of a.txt is "Zhang San Li Si Zhang San" in three lines, then assign Zhang San to the variable %%i, and then execute to find "Zhang San" in b.txt. If not found, it means that the first half of the second line statement is wrong, so the command after || is executed. Then, the second time Zhang San is assigned to %%i and then Zhang San is found in b.txt
Rem can be found, the statement is correct, and the latter command will not be executed. I don't know if the explanation is correct
17. Can the file type in the registry be modified through a batch to realize "a certain type of file cannot be opened"?
@echo off
reg add HKCR\.bat /f /ve /d bat >nul 2>nul
reg add HKCR\.cmd /f /ve /d cmd >nul 2>nul
echo.
echo Oh, bat/cmd files cannot be opened or edited!
pause >nul
Rem Bat and cmd suffix files cannot be opened. If you need to open them, you can restore the registry. rem Of course, the premise is that there is a registry backup

A sofa, heh heh! Learn...

Learn slowly, no fear.

It's a rather long note. It seems I need to digest it slowly.

The building owner has worked hard. The materials from shallow to deep are really suitable for learning

THANK FOR YOU SHARING!

Wow, so long, heh, learning

Learned a lot from this note, easy to understand

Learning is endless. Really thank the LZ for sharing. You've worked hard.

Well, that's great. If you like it, just go ahead and learn.