In Windows NT XP, Vista, 7, 8, 10.Command Prompt cmd.They can be used to automate file.Check File System Windows Cmd Variables' title='Check File System Windows Cmd Variables' />Variables and Expressions.Table of Contents.Variables. Variable types Auto.Hotkey has no explicitly defined variable types.However, a variable containing only digits with an optional decimal point is automatically interpreted as a number when a math operation or comparison requires it.To improve performance, numbers are cached internally to avoid conversions tofrom strings.Variable scope and declarations With the exception of local variables in functions, all variables are global that is, their contents may be read or altered by any part of the script.Except where noted on the functions page, variables do not need to be declared they come into existence simply by using them and each variable starts off emptyblank.Variable names Variable names are not case sensitive for example, Current.Date is the same as currentdate.Variable names may be up to 2.Due to style conventions, it is generally better to name your variables using only letters, numbers, and the underscore character for example Cursor.Position, TotalItems, and entryisvalid.This style allows people familiar with other computer languages to understand your scripts more easily.Also, if you use the same conventions in Auto.Hotkey as you use in other languages, you may find it easier to re read your own scripts.Although a variable name may consist entirely of digits, this is generally used only for incoming command line parameters.Such numeric names cannot be used in expressions because they would be seen as numbers rather than variables.Since the words AND, OR, and NOT are used as operators in expressions, generally they should not be used as variable names.Check File System Windows Cmd Variables' title='Check File System Windows Cmd Variables' />Using such names in an expression would prevent proper evaluation.Storing values in variables To store a string or number in a variable, there are two methods traditional and expression.The traditional method uses the equal sign operator to assign unquoted literal strings or variables enclosed in percent signs.For example My. Number 1.My. String This is a literal string.Copy. Of. Var Var With the operator, percent signs are required to retrieve a variables contents.By contrast, the expression method uses the colon equal operator to store numbers, quoted strings, and other types of expressions.The following examples are functionally identical to the previous ones My.Number 1. 23. My.String This is a literal string.Copy. Of. Var Var Unlike its counterpart in the previous section, percent signs are not used with the operator.The latter method is preferred by many due to its greater clarity, and because it supports an expression syntax nearly identical to that in many other languages.LV0J.png' alt='Check File System Windows Cmd Variables' title='Check File System Windows Cmd Variables' />An environment variable is a dynamicnamed value that can affect the way running processes will behave on a computer.They are part of the environment in which a.ATimeIdle The number of milliseconds that have elapsed since the system last received keyboard, mouse, or other input.This is useful for determining whether the.You may have guessed from the above that there are two methods to erase the contents of a variable that is, to make it blank My.Var. My. Var The empty pair of quotes above should be used only with the operator because if it were used with the operator, it would store two literal quote characters inside the variable.Retrieving the contents of variables Like the two methods of storing values, there are also two methods for retrieving them traditional and expression.The traditional method requires that each variable name be enclosed in percent signs to retrieve its contents.For example Msg. Box The value in the variable named Var is Var.Copy. Of. Var VarBy contrast, the expression method omits the percent signs around variable names, but encloses literal strings in quotes.Thus, the following are the expression equivalents of the previous examples Msg.Box The value in the variable named Var is.Var. A period is used to concatenate join two strings.Copy. Of. Var Var.In the Msg. Box line above, a percent sign and a space is used to change the parameter from traditional to expression mode.This is necessary because the traditional method is used by default by all commands except where otherwise documented.However, certain parameters of some commands are documented as accepting expressions, in which case the leading percent sign is permitted but not necessary.For example, all of the following are effectively identical because Sleeps first parameter is expression capable Sleep Milliseconds.To. Wait. Sleep Milliseconds.To. Wait. Sleep Milliseconds.To. Wait. Comparing variables Please read the expressions section below for important notes about the different kinds of comparisons, especially about when to use parentheses.Expressions. Expressions are used to perform one or more operations upon a series of variables, literal strings, andor literal numbers.Variable names in an expression are not enclosed in percent signs except for pseudo arrays and other double references.Consequently, literal strings must be enclosed in double quotes to distinguish them from variables.For example if Current.Setting 1. 00 or Found.Color lt Blue. Msg.Box The setting is too high or the wrong color is present.In the example above, Blue appears in quotes because it is a literal string.To include an actual quote character inside a literal string, specify two consecutive quotes as shown twice in this example She said, An apple a day.Important An if statement that contains an expression is differentiated from a traditional if statement such as If Found.Color lt Blue by making the character after the word if an open parenthesis.Although this is usually accomplished by enclosing the entire expression in parentheses, it can also be done with something like if x 0 and y 0.In addition, the open parenthesis may be omitted entirely if the first item after the word if is a function call or an operator such as not or.Empty strings To specify an empty string in an expression, use an empty pair of quotes.For example, the statement if My.Var lt would be true if My.Var is not blank.However, in a traditional if, a pair of empty quotes is treated literally.For example, the statement if My.Var is true only if My.Var contains an actual pair of quotes.Thus, to check if a variable is blank with a traditional if, use or lt with nothing on the right side as in this example if Var.On a related note, any invalid expression such as x 3 yields an empty string.Storing the result of an expression To assign a result to a variable, use the operator.For example Net. Price Price 1 Discount1.Boolean values When an expression is required to evaluate to true or false such as an IF statement, a blank or zero result is considered false and all other results are considered true.For example, the statement if Item.Count would be false only if Item.Count is blank or 0.Similarly, the expression if not Item.Count would yield the opposite result.Operators such as NOTANDOR lt automatically produce a true or false value they yield 1 for true and 0 for false.For example, in the following expression, the variable Done is assigned 1 if either of the conditions is true Done AIndex 5 or Found.It. As hinted above, a variable can be used to hold a false value simply by making it blank or assigning 0 to it.To take advantage of this, the shorthand statement if Done can be used to check whether the variable Done is true or false.The words true and false are built in variables containing 1 and 0.They can be used to make a script more readable as in these examples Case.Sensitive false. Continue.Search true. Integers and floating point Within an expression, numbers are considered to be floating point if they contain a decimal point otherwise, they are integers.For most operators such as addition and multiplication if either of the inputs is a floating point number, the result will also be a floating point number.Within expressions and non expressions alike, integers may be written in either hexadecimal or decimal format.Hexadecimal numbers all start with the prefix 0x.For example, Sleep 0x.FF is equivalent to Sleep 2.In v. 1. 0. 4. 6.E 4. Force an expression An expression can be used in a parameter that does not directly support it except Output.Var parameters by preceding the expression with a percent sign and a space or tab.In v. 1. 1. 2. 1, this prefix can be used in the Input.Var parameters of all commands except the traditional IF commands use If expression instead.This technique is often used to access arrays.For example File.Windows ProgrammingProgramming CMD Wikibooks, open books for an open world.In Windows NT XP, Vista, 7, 8, 1.Command Prompt cmd.They can be used to automate file system tasks such as backups or basic installations and can be used with other command line utilities as well.The batch files can be considered to be a simple scripting language with logic and jumps.The advantages of using batch files are the ease of writing them, the ability to edit the files without compiling anything, their cross compatibility across Windows NT Operating Systems and their inherent ability to manipulate file systems due to their basis on MS DOS.Batch file scripts are not case sensitive, although strings and data are.The file is controlled by a list of commands separated into lines which are run like normal commands would be at the Command Prompt, although some functionality is different.Batch files can be run from Windows Explorer but the console used to display them closes automatically at the end of the batch file, so a command at the end that prevents instantaneous exit is needed for any remaining output to be read before the console window closes.Although the batch files are able to manipulate their environment, such as color settings and environment variables, the changes are all temporary, as in a standard Command Prompt session.Color settings, however, are retained on later editions of Windows NT.In order to try to learn about batch files, it is useful to understand Command Prompt commands.See Guide to Windows commands.Batch FileeditThe script is kept inside a batch file, with the extension.Although. bat is more recognisable, as it was used in the MS DOS environment that preceded the Command Prompt, the Command Prompts interpretations of batch files is very different to the manner of interpreting DOS batch files, and.Command Prompt, so using the.Execution starts at the top of the file and ends at the end.When the end of the file is reached, the file exits to the Command Prompt if it was invoked from there, or the console window closes if it was invoked from Windows Explorer or the START command.ECHO CommandeditTypically, batch files start with the echo off command, which stops the input and prompt from being displayed during execution, so only the command output is displayed.The symbol prevents a command from having input and its prompt displayed, so it is used on the echo off command to prevent that first command from displaying the input and prompt.In order to print lines, the ECHO command is used again, but this time with a text parameter other than off.ECHO. Hello WorldThe period.ON or OFF rather than turn input and prompt displaying on and off.The last line in a code should then be.Echo on will turn the inputprompt display back on, just in case the program exits to the Command Prompt where without the command echo on, there will be no visible prompt left for use.HINT Starting with Windows XP, the ECHO ON command is optional.The command interpreter automatically enables it after the BAT file terminates.Hello World ExampleeditUsing the code above, we can make a hello world program like so.ECHO Hello World In batch files there are two ways of writing comments.Firstly there is the form.REM Comment here.This form is included as it was in the MS DOS batch file script.The other form is this.Comment here. This form is generally favoured, for being faster to execute and write, and also for being easy to differentiate from normal commands.For this type of comment only two double colons are needed and the comment ends at the end of the line.Batch files have no multi line comment types.You can also add a comment to the end of the command.Comment here. VariableseditWe access variables with the SET command.SET lets us set the value for a variable, and delete a variable.The variables used are environment variables, which are set up to correspond to the systems environment variables, although they are not the actual environment variables of the system and changing them will not change system environment variables.For example. SET nameJohn Smith.This command creates an environment variable called name, and sets its value to the string John Smith.The first space is ignored as the value entered records from the first non whitespace character encountered after the sign.Set also allows the storing of integers specifically, using the A parameter.SET A number3. 8.This command creates an environment variable named number with the integer value 3.This number can be involved in arithmetic and numerical logic, but without the A parameter all that is stored are the characters 3 and 8, which cant be used as numbers.Variables are accessed by surrounding the name with s.This substitutes the value straight into a command, and does not point to the variable.For example. SET nameJohn Smith.This file would return the text John Smith.A string number can be converted to an integer number in a similar fashion.SET A numnum. This code creates a string called num, then overwrites it with an integer with the numerical value represented by the string contents of num, in this case 3.The set command can also be used for input.SET P varEnter a value for var.This command displays Enter a value for var and when the user enters the data, var is given that value.Be aware, if the user presses enter without entering anything then the value in var is unchanged, so for the sake of a prompt it is often best to give a default value, or clear the value for the variable first if it has been used before.SET P varEnter a value for var.Below is an example.SET P answer Enter name of file to delete.DEL P answer. This batch file gets the name of a file to delete and then uses the DEL command with the prompt parameter P to ask the user if theyre sure they want to delete the file.Flow ControleditConditionalseditThe IF command can be used to create program logic in batch files.The IF command allows three basic checks, on the ERRORLEVEL, the equality of two strings, and the existence of a file or folder.The first check on the ERRORLEVEL will check to see if it is greater than or equal to a certain number.IF ERRORLEVEL 5 ECHO.The ERRORLEVEL is at least 5.For this style the first parameter is always ERRORLEVEL, and the second is the value it checks against.In this case, if the ERRORLEVEL is at least 5 then the command at the end of the line is executed, outputting the message The ERRORLEVEL is at least 5.The second form is a check between two strings.IF str. 1Hello. ECHO.The strings are equal.Here the first parameter is two strings either side of the double, symbolising a check to see if they are equal.If the variable str.Hello., a check which is case sensitive, then The strings are equal.In the case that you wish to make the check case insensitive you would rewrite it as following.IF I str. 1Hello.ECHO. The strings are equal.Now, for example, str.HELLO. but the check would still result in the command being executed at the end as the check is now case insensitive.The final basic IF type is the existence check, to see if a file or folder exists.IF EXIST myfile. txt TYPE myfile.Here if the file myfile.TYPE myfile. txt is executed which displays the contents of myfile.All of the preceding examples have an optional NOT parameter that can be written after the IF which will execute the command at the end of the line if the condition is not true.For example. IF NOT EXIST myfile.ECHO. File missing.Which will output File missing.There are a few other IF types with command extensions, which can be seen with the IF The ELSE operator can be used with a combination of brackets to provide multi line logical statements that provide an alternative set of commands if the condition is not true.Unlike some languages, in batch files the scripting requires that the lines IF condition, ELSE and are written very specifically like that.It is possible, however, to re write it to use single line outcomes all on one line.IF condition command if true ELSE command if false.Below is an example of the ELSE operator in use. Download Desperation Band Update Live Update there. Prompt for input.SET P answerEnter filename to delete.IF EXIST answer. DEL P answer.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
November 2017
Categories |