Windows batch file substitution

Use the FOR command to trim spaces at the beginning of a variable. In this example the variable to be trimmed is str.

The FOR command can be used to safely remove quotes surrounding a string. If the string does not have quotes then it will remain unchanged. Trimming spaces at the end of a variable seems a little tricky. The following example shows how to use a FOR loop to trim up to 31 spaces from the end of a string. To use quotation marks, you must use usebackq. Otherwise, the quotation marks are interpreted as defining a literal string to parse. Skip to main content. This browser is no longer supported.

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View all page feedback. In this article. Represents a replaceable parameter. Specifies one or more files, directories, or text strings, or a range of values on which to run the command. But this behaviour does mean that you cannot change a variable's value inside a block! Advanced variable substitution Now, an advanced technique.

PDF - Download batch-file for free. Previous Next. This website is not affiliated with Stack Overflow. The "script" in this context being a line - or block - of code, surrounded by round brackets:. In the above example, the ECHO command is evaluated as Hello when the script is read into memory, so the script will echo Hello forever, however many passes are made through the script. The way to achieve the more "traditional" variable behaviour of the variable being expanded whilst the script is running is to enable "delayed expansion".

This involves adding that command into the script prior to the loop instruction usually a FOR loop, in a batch script , and using an exclamation mark! Now, an advanced technique. Using the CALL command allows the batch command processor to expand a variable located on the same line of the script. This can deliver multilevel expansion, by repeated CALL and modifier use. This is useful in, for example, a FOR loop. As in the following example, where we have a numbered list of variables:.