批處理文件識別

Question

我有一個有趣的案例有一個批處理文件，它做以下的事情打轉轉：

1. 移動廣口瓶中，目錄
2. 將所有的jar文件目錄的字符串（類路徑）
3. 運行的jar

我得到的問題是，它沒有找到，同時建立字符串的新罐，但它發現現有的罐子，所以如果我運行兩次都沒問題。

要檢測的罐子，我使用的是這樣的：

set cp= 

for %%a in ("jars/*.jar") do call :concat jars/%%a 

:concat 

set cp=%cp%;%1 

如果任何人有一個解釋或解決方案，我想聽聽吧！

Answer 1

我發現這個問題 - 副本是來自全國各地的網絡，所以這需要時間。當我添加timeout 4 > NUL或類似的東西時，一切都很好。

Answer 2

請參閱！var！ VS％VAR％

& seperates commands on a line. 

&& executes this command only if previous command's errorlevel is 0. 

|| (not used above) executes this command only if previous command's errorlevel is NOT 0 

> output to a file 

>> append output to a file 

< input from a file 

| output of one command into the input of another command 

^ escapes any of the above, including itself, if needed to be passed to a program 

" parameters with spaces must be enclosed in quotes 

+ used with copy to concatinate files. E.G. copy file1+file2 newfile 

, used with copy to indicate missing parameters. This updates the files modified date. E.G. copy /b file1,, 

%variablename% a inbuilt or user set environmental variable 

!variablename! a user set environmental variable expanded at execution time, turned with SelLocal EnableDelayedExpansion command 

%<number> (%1) the nth command line parameter passed to a batch file. %0 is the batchfile's name. 

%* (%*) the entire command line. 

%<a letter> or %%<a letter> (%A or %%A) the variable in a for loop. Single % sign at command prompt and double % sign in a batch file. 


. 
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Answer 3

set "cp=" 

setlocal enableDelayedExpansion 
for %%a in ("jars/*.jar") do set "cp=!cp!;"%%~a"" 
endlocal &&(
    set "cp=%cp%" 
) 
echo %cp%