Useful bat files. Writing bat files - examples of batch files

As experience has shown, batch files, i.e. batch files are very popular among system administrators who use them for their automation purposes. And today we continue to study these same bat files; we will not consider the basics, but will move on to more advanced things.

In the first article Writing bat files - examples of batch files, we looked at simple examples of using batch files, but as it turned out, writing batch files is very interesting to almost everyone and everyone wants to learn something more complex, with which you can further simplify the automation of some processes.

Example 1 – deleting old archives

When archiving something, many people are interested in the question “ How to delete old archives as unnecessary using a batch file? " For example, they are all in one folder and you need to delete all archives that are older than 14 days. After I read the manuals and surfed the Internet, I can suggest the following method.

You can make it so that only a certain number of archives will be stored in the folder with archives, respectively the latest ones ( those. just in our case over the last 2 weeks).

This is done using two commands. The first is DIR, i.e. just read all the files in one folder and write their names in text file.

dir D:\arhiv\*.rar /a:-D/b/o:-D > list_of_files.txt

• dir D:\arhiv\*.rar– this means that we read everything rar archives in folder D:\arhiv\;
• /a:-D– this means that all files with the specified attributes will be displayed, the -D key means that we only need files, not directories, the prefix “-” just means negation, i.e. not directories, if we just wrote D, then it would read directories too;
• /b– this is the output of file names only;
• /o:-D– this is sorting, the –D key means that sorting will be performed by date, but first the older ones, to fix this we already know that the prefix “-” will help us;
• > — means that the output will be redirected to the file list_of_files.txt, you can name it differently.

So we counted all our archives and wrote them into a file, then we need to go through all these files and leave only 14 pieces, i.e. over the last 2 weeks. We do this using the command FOR, it is a kind of loop that performs a specific action for each file in a folder or each line in a file, as in our case.

• for– the team itself for the bulkhead;
• /F "skip=13"– this is a key with a parameter that means that the first 13 files do not need to be processed, i.e. we skip them. Why 13 and not 14 yes because 14 archive ( those. today's, which should be created when executing this batch file) has not yet been created, therefore 13;
• %%i– a variable that stores the name of the current file;
• In (list_of_files.txt)– means that iterate over all lines in this particular file;
• do (del /Q "%%i")- says what needs to be done with each one, in our case we simply delete these files using the del /Q key /Q, so that we are not asked for confirmation before deleting. For tests, I advise replacing del /Q with echo, i.e. just display those files.

In total, we got this batch file:

dir D:\arhiv\*.rar /a:-D/b/o:-D > list_of_files.txt

for /F “skip=13” %%i in (list_of_files.txt) do (del /Q “%%i”)

Accordingly, after these lines you can write the archiving code itself, and in the end we will get that only 14 archives will be stored in our folder, of course, the most recent ones.

Example 2 - Using Variables

You can even use variables in batch files, just like in a real programming language. Let's consider simplest example using variables, for example, we want to multiply by 2 the number that we will enter in the field when running the batch file.

@echo off

SET /a c=%a%*%b%

echo %c%

As you understand, variables are set using the SET command. In order to use the variable in the future, we insert a percent sign (%) on both sides of the variable so that the command line understands that this is a variable.

• @echo off– so that our commands are not displayed on the screen;
• SET a=2– we simply set the variable “a” to a value;
• SET /p b=[enter second number to multiply]– we set the variable “b” to the value that we enter into the field, so that the batch worker understands that we want to enter the value of the variable ourselves, the /p key is used;
• SET /a c=%a%*%b%— we set the variable “c” to the result of our expression ( in our example this is multiplication);
• echo %c%— display the value of the variable “c”;
• pause- we simply pause the execution of our bat file in order to simply see all the results.

By the way, in order for Russian letters to be displayed normally on the command line, save the bat file in DOS-866 encoding.

We've sorted out the variables, now let's apply this to our first example, let's say we want to leave not 14 archives, but the number that we want, for this, when you launch the batch file, we will enter the number of archives that need to be saved. It will look something like this:

@echo off

dir D:\test\*.rar /a:-D/b/o:-D > list_of_files.txt

for /F “skip=%chislo%” %%i in (list_of_files.txt) do (del /Q “%%i”)

Well, something like this, of course, in practice this may not be needed, but at least we learned how to use variables.

About variables, I also want to say that there are such system variables as:

%DATE%— shows the current date.

%TIME%— shows the current time.

For example, run the following code:

echo %DATE%

echo %time:~0,-3%

I wrote the %TIME% variable in exactly this way, in order for the result to be displayed in a more readable form, try writing %TIME% and % TIME:~0.-3% for you, in the second case the last 3 characters will be removed.

In fact, there are more system variables; these may just be required more often than others.

Example 3 – IF Conditional Execution Statement

As in other full-fledged languages, you can use the IF conditional execution operator in batch files. Let's give a small example, the batch file simply checks whether the file exists or not:

@echo off

IF EXIST test.txt (

echo File exists

echo There is no such file

IF EXIST test.txt– this is exactly where the file is checked.

After, in parentheses, comes what we want to do if the file exists, and if the file does not exist, then after ELSE, comes what needs to be done if the file does not exist.

Now let’s slightly modify our example with multiplying the number we entered by 2, simply, if we suddenly enter zero, we will display the corresponding message and ask you to enter the number again.

@echo off

SET /p b=[enter second number to multiply]

SET /a c=%a%*%b%

if %c%==0 (echo you entered the number 0, enter another) else echo %c%

if %c%==0 (goto:metka)

Everything here is already familiar, the only thing is that when comparing the variable “c” the comparison operator == ( two equals), because simply equal (=) is an assignment operator. If you noticed, I used the goto operator here, i.e. move to the desired label. In other words, we put a label and, depending on the result of checking the condition, the transition to the desired label will be carried out.

Now I would like to note what many people use in their work, for example, to create an archive, winrar program and, of course, they use it in their batch files, but many ask questions about keys that relate to winrar. Don't confuse the winrar keys, they are used only for this program, and not for everything that is in the batch files, i.e. command line, for example, if you use 7zip, then the keys will be different. As for winrar keys, the complete and best reference book, in my opinion, is, of course, in winrare itself. To view a description of winrar keys, open the winrar program, go to the Help menu, then click " Content", and then select the line " Command line mode", where there will be a description of all the keys, even simple examples are given. Accordingly, if you have the English version of winrar, then the meaning is the same, only everything will be in English.

This concludes our second part of studying batch files. Good luck!

Windows bat files are a convenient way to perform various tasks on a PC, which is actively used by computer experts. They allow you to automate daily tasks, reduce their execution time and turn a complex process into something feasible for the average user. This article presents the basic capabilities of batch files and recommendations for writing them yourself.

Automation made easy

How to create a bat file? To do this you need to do the following:

1. In any text editor, for example, Notepad or WordPad, create Text Document.
2. Write your commands in it, starting with @echo , and then (each time on a new line) title [name of the batch script], echo [message that will be displayed on the screen] and pause.
3. Save the text in an electronic document with the .bat extension (for example, test.bat).
4. To run, double-click on the newly created batch file.
5. To edit it, you need to click on it right click mouse and select “Change” from the context menu.

The raw file will look something like this:

title This is your first bat file script!

echo Welcome to the batch processing script!

We will discuss bat file commands and their use in more detail below.

Step 1: Create a software script

Let's assume that a user often has problems with the Network. He constantly uses the command line, typing ipconfig and pinging Google to troubleshoot network problems. After a while, the user realizes that it would be much more effective if he wrote a simple bat file, wrote it to his USB drive and ran it on the computers he diagnoses.

Creating a new text document

A batch file makes it easy to perform repetitive tasks on your computer using a command line Windows strings. Below is an example of a script responsible for displaying some text on the screen. Before creating a bat file, you should right-click on an empty space in the directory and select “Create”, and then “Text Document”.

Adding code

Double clicking on this new text document will open the default one text editor. You can copy and paste the example code above into a text entry.

Preservation

The above script displays the text “Welcome to the Batch Processing Script!” on the screen. Electronic document you need to record it by selecting the text editor menu item “File”, “Save As”, and then specify the desired name of the bat file. It should be completed with a .bat extension (for example, welcome.bat) and click OK. To display the Cyrillic alphabet correctly, in some cases you should make sure that the encoding is selected correctly. For example, when using a Russified console Windows systems The NT document must be saved in the CP866. Now you should double click on the bat file shortcut to activate it.

But the following message will appear on the screen:

"Welcome to the batch script! Press any key to continue..."

If the bat file does not start, users recommend going to the registry and deleting the key:

"HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.BAT\UserChoice."

Don't think that's all that batch scripts can do. Script parameters are modified versions of command line commands, so the user is limited only by their capabilities. And they are quite extensive.

Step 2: Get to Know Some Commands

If a PC user is familiar with how to execute DOS console commands, then he will be a master at creating software scripts because they are the same language. The lines in the bat files will tell the cmd.exe interpreter everything that is required of it. This saves time and effort. In addition, it is possible to specify some logic (for example, simple loops, conditionals, etc., which are conceptually similar to procedural programming).

Built-in Commands

1. @echo is a bat file command that will allow you to see the script running on the command line. It is used to view the progress of production code. If the batch file has any problems, then this command will allow you to quickly localize problems. Adding off makes it possible to quickly terminate code execution, avoiding unnecessary information being displayed on the screen.

2. Title provides the same functionality as a tag