Windows批处理文件有哪些不太为人所知,但很重要和有用的特性?

指南:

每个答案一个特征 给出特性的简短描述和示例,而不仅仅是文档链接 将答案限制在本地功能,即不需要额外的软件,如Windows资源包

澄清:这里我们指的是由cmd.exe处理的脚本,这是WinNT变体的默认值。

(请参见:Windows批处理文件:.bat vs .cmd?)


当前回答

要从文件的第一行开始设置一个环境变量,我使用以下命令:

rem a.txt contains one line: abc123
set /p DATA=<a.txt
echo data: %DATA%

这将输出:abc123

其他回答

抽取随机的文本行

@echo off

:: Get time (alas, it's only HH:MM xM

for /f %%a in ('time /t') do set zD1=%%a



:: Get last digit of MM

set zD2=%zD1:~4,1%



:: Seed the randomizer, if needed

if not defined zNUM1 set /a zNUM1=%zD2%


:: Get a kinda random number

set /a zNUM1=zNUM1 * 214013 + 2531011

set /a zNUM2=zNUM1 ^>^> 16 ^& 0x7fff


:: Pull off the first digit

:: (Last digit would be better, but it's late, and I'm tired)

set zIDX=%zNUM2:~0,1%


:: Map it down to 0-3

set /a zIDX=zIDX/3


:: Finally, we can set do some proper initialization

set /a zIIDX=0

set zLO=

set zLL=""


:: Step through each line in the file, looking for line zIDX

for /f "delims=@" %%a in (c:\lines.txt) do call :zoo  %zIDX%  %%a


:: If line zIDX wasn't found, we'll settle for zee LastLine

if "%zLO%"=="" set zLO=%zLL%

goto awdun


:: See if the current line is line zIDX

:zoo


:: Save string of all parms

set zALL=%*


:: Strip off the first parm (sure hope lines aren't longer than 254 chars)

set zWORDS=%zALL:~2,255%


:: Make this line zee LastLine

set zLL=%zWORDS%


:: If this is the line we're looking for, make it zee LineOut

if {%1}=={%zIIDX%} set zLO=%zWORDS%


:: Keep track of line numbers

set /a zIIDX=%zIIDX% + 1

goto :eof




:awdun

echo ==%zLO%==


:: Be socially responsible

set zALL=

set zD1=

set zD2=

set zIDX=

set zIIDX=

set zLL=

set zLO=

:: But don't mess with seed

::set zNUM1=

set zNUM2=

set zWORDS=

我总是发现很难阅读每行用关键字标记的注释:

REM blah blah blah

易于阅读:

:: blah blah blah
PAUSE

停止执行并显示如下提示:

Press any key to continue . . .

如果你想通过在Windows资源管理器中双击一个批处理来运行它,并且想实际看到输出,而不仅仅是命令窗口的一闪而过,这很有用。

继续行:

call C:\WINDOWS\system32\ntbackup.exe ^
    backup ^
    /V:yes ^
    /R:no ^
    /RS:no ^
    /HC:off ^
    /M normal ^
    /L:s ^
    @daily.bks ^
    /F daily.bkf

对于具有数字计数器的循环(输出1到10):

for /l %i in (1,1,10) do echo %i