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Editor to share with you how to use the DOS loop for command, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

I. basic format

FOR% variable IN (set) DO command [command-parameters]

% variable specifies a single letter to represent a replaceable parameter.

(set) specify a file or group of files. You can use wildcards.

Command specifies the commands to be executed on each file.

Command-parameters specifies parameters or command line switches for specific commands.

Parameters: FOR has 4 parameters / d / l / r / f their role I will explain with examples below

Now let's talk about the meaning of each parameter.

Second, parameter / d

FOR / D% variable IN (set) DO command [command-parameters]

If the set contains wildcards, the assignment matches the directory name, not the file name.

If the Set (that is, the "related file or command" I wrote above) contains wildcards (* and?), the specified Command is executed for each directory that matches the Set (instead of the filegroup in the specified directory).

This parameter is mainly used for directory search, but not for files. Take a look at this example.

@ echo offfor / d% I in (c:\ *) do echo% ipause

The run will print out all the directory names under the root directory of the C disk, and none of the file names will be displayed!

Another one, for example, we need to type out the name of the folder under the current path with only 1-3 letters.

@ echo offfor / d% I in Do echo ipause

In this way, if you have a directory name with only 1-3 letters in the current directory, it will be displayed, but if not, it will not be displayed.

Can you explain the * and? The role of the number, the * sign represents any N characters, and? The number represents only any character.

Know the effect, give everyone a question to think about!

@ echo offfor / d% I in (window?) Do echo ipause

If you save it to disk C, what will be displayed? See for yourself! Display: windows

The / D parameter can only display the name of the directory under the current directory, which we should pay attention to!

3. Parameter / R

FOR / R [[drive:] path]% variable IN (set) DO command [command-parameters]

Check the directory tree rooted in [drive:] path and point to the FOR statement in each directory. If no directory is specified after / R, the current directory is used. If the set is only a single point (.) Character, the directory tree is enumerated.

Recursion

As we know above, / D can only display the directory name under the current path, so now this / R is also related to the directory, what can he do? Don't worry, he is much more powerful than / D.

It can read all the file names under the current or your specified path, note that it is the file name, what is the use to see the example!

Please note 2 points:

If the file name in set contains a wildcard character (? Or *), enumerate all files that match set in the directory specified by the / R parameter and its subdirectories below, and directories without matching files are not enumerated.

Conversely, if the set is a specific file name and does not contain wildcards, the directory tree is enumerated (that is, the directory and all subdirectories below it are enumerated), regardless of whether the specified file in set exists or not. This is the same as the single point (.) enumerated directory tree mentioned earlier, which represents the current directory and can also be regarded as a file.

Example:

@ echo offfor / r c:\% I in (* .exe) do echo% ipause

Let's save this BAT to D disk anywhere and execute it, and I will see that he lists all the EXE files under the root directory of C disk and the subdirectory of each directory!

Example:

@ echo offfor / r% I in (* .exe) do @ echo% ipause

The parameters are different! This command is not preceded by the C:\, that is, the search path, so that he will use the current directory as the search path, such as your BAT, if you put him under the d:\ test directory to execute, then he will list all the EXE files in the D:\ test directory and his subdirectories!

Example:

@ echo offfor / r c:\% I in (boot.ini) do echo% ipause

Run this example and find that all directories on disk c are enumerated. In order to enumerate only the directories where boot.ini exists, it can be changed to the following:

@ echo offfor / r c:\% I in (boot.ini) do if exist% I echo% ipause

It's nice to search for files with this command.

This parameter should be understood! It's still a funny order!

4. Parameters / L

FOR / L% variable IN (start,step,end) DO command [command-parameters]

This set represents a sequence of numbers from beginning to end in increments. Therefore, (1) the sequence 1 2 3 4 5 will be produced, and the sequence 5 4 3 2 1 will be generated (5 4 3 21).

Use the iteration variable to set the start value (Start#), and then step through a range of values until the value exceeds the set end value (End#). / L will execute iterative variables by comparing Start# with End#. This command is executed if Start# is less than End#,. If the iteration variable exceeds End#, the command interpreter exits the loop. You can also use a negative Step# to incrementally execute values in this range. For example, (1) generate sequences 1 2 3 4 5), and (5) generate sequences (5 4 3 2 1). The syntax is:

Look at this means a little dizzy! Let's look at the example and we won't get dizzy!

@ echo offfor / l% I in (1meme 1je 5) do @ echo% ipause

Save the execution to see the effect, he will print 5 numbers from 1, 2, 3, 4, 5, this parameter means to add 1 at a time from 1 to 5!

When you get dizzy, it's useful to print a number. Okay, to satisfy everyone, take a look at this example.

@ echo offfor / l% I in (1penny 1je 5) do start cmdpause

After the implementation is not startled, why more than 5 CMD windows, ha ha! What will happen if you change that from (1pm) to (1pm) 65535? I will tell you first that 65535 CMD windows will be opened. You are strong if you don't die!

Of course, we can also change that start cmd to md% I so that we can set up a specified directory! The name is 1-65535.

After looking at this parameter that I have given the nature of destruction, let's look at the last parameter.

5. Parameters / F

\ iteration and file parsing

Use file parsing to process command output, strings, and file contents. Use iterative variables to define the content or string to check, and use various options options to further modify the parsing. Use the options token option to specify which tokens should be passed as iteration variables. Note that when there is no token option, / F will only check the first token.

The file parsing process involves reading the output, string, or file contents, dividing it into separate lines of text, and parsing each line into zero or more tokens. The for loop is then called by setting the value of the iteration variable to the token. By default, / F passes the first white space delimiter on each line of each file. Skip blank lines.

The detailed help format is:

FOR / F ["options"]% variable IN (file-set) DO command [command-parameters]

FOR / F ["options"]% variable IN ("string") DO command [command-parameters]

FOR / F ["options"]% variable IN ('command') DO command [command-parameters]

The quoted string "options" includes one or more keywords that specify different parsing options. These keywords are:

Eol=c-refers to the end of a line comment character (just one)

Skip=n-refers to the number of lines ignored at the beginning of the file.

Delims=xxx-refers to the delimiter set. This replaces the default delimiter set of spaces and tabbed keys.

Tokens=x,y,m-n-refers to which symbol of each line is passed to the for itself of each iteration. This results in the allocation of additional variable names. The mmurn format is a range. Specify the mth through the nth symbol. If the last character in the symbol string is an asterisk, the additional variable is assigned and accepts the reserved text of the line after the last symbol is parsed. After testing, this parameter can only distinguish 31 fields at most.

Usebackq-use quotation marks (the key to the left of the number 1 on the keypad).

When the parameter usebackq is not used: file-set represents a file, but cannot contain spaces

Double quotation marks indicate a string, that is, "string"

Single quotation marks indicate the execution of a command, that is, 'command'

When using the parameter usebackq: both file-set and "file-set" represent files

When there is a space in the file path or name, it can be enclosed in double quotation marks

Single quotation marks indicate a string, that is, 'string'

Quotation marks indicate the execution of the command, that is, `command`

The above is using for /? The help information obtained by the command is copied directly.

I'm dizzy! Let me give you an example to help you understand these parameters!

The For command example 1 is a rime *

@ echo offrem first set up a temporary file test.txtecho; comment line, this is a temporary file, delete > test.txtecho 11, 12, 13, 14, 15, 16 > > test.txtecho 21, 22, 23, 24, 25, 26 > > test.txtecho 31-32-33-34-35-36 > > test.txtFOR / F "eol=; tokens=1,3* delims=,-"% I in (test.txt) do echo% I% j% kPauseDel test.txt

Run to display the results:

11, 13, 14, 15, 16.

21, 23, 24, 25, 26.

31 paragraph 33 paragraph 34-35-36 paragraph

Please press any key to continue. . .

Why is this? Let me explain:

Behavior comment lines at the beginning of eol=; semicolon

Tokens=1,3* assigns paragraph 1, paragraph 3 and the remaining fields of each line to the variable%% iMagery% jjjjm% k, respectively.

Delims=,- (a space after a minus sign) is separated by a comma minus sign and a space, and the space must be placed last.

For command example 2 VRO *

@ echo offFOR / F "eol= delims=" I in (test.txt) do echo iPause

The run will display the full contents of the test.txt, including comment lines, without explanation.

For command example 3 VR commands *

In addition, the / F parameter can also see this example with the result of the output command.

@ echo offFOR / F "delims="% I in ('net user') do @ echo% ipause

In this way, all the account names of your machine will come out and quote the contents of the extension in two single quotation marks to indicate that when the command is executed, FOR will return the result of each line of the command, and add that "delims=" so that the line of my space can be displayed in the whole line, and only the left column of the space will be displayed if you don't add it.

The above is all the contents of the article "how to use the DOS Loop for Command". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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