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?)
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
将错误级别设置为你想要的任何数字的方法:
CMD /C EXIT number
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=
一行中包含多个命令,在很多情况下都很有用:
&用于组合两个命令,执行command1和command2 &&一个条件组合,如果command1成功完成,则执行command2 仅当command1未成功完成时才执行Command2。
例子:
:: ** Edit the most recent .TXT file and exit, useful in a .CMD / .BAT **
FOR /F %%I IN ('DIR *.TXT /B /O:-N') DO NOTEPAD %%I & EXIT
:: ** If exist any .TXT file, display the list in NOTEPAD, if not it
:: ** exits without any error (note the && and the 2> error redirection)
DIR *.TXT > TXT.LST 2> NUL && NOTEPAD TXT.LST
您可以将if语句链接起来,以获得类似短路布尔' and'的效果。
if foo if bar baz
关于使用::而不是REM进行评论:要小心!::是CALL标签的一种特殊情况,作用类似于注释。当在括号内使用时,例如在for或IF循环中,函数将提前退出。调试非常令人沮丧!
详细描述请参见http://www.ss64.com/nt/rem.html。
(添加一个新的答案,而不是上面第一次提到的评论,因为我还不值得评论:0)
为了从脚本内部解析stdin,你需要使用For和FIND命令:
for /f "tokens=*" %%g in ('find /V ""') do (
:: do what you want with %%g
echo %%g
)