Question

我担心仍然患有扩张功能障碍。我试图从日志文件的开头剥离GTR而不是100行。以下看起来像它应该工作，但如图所示，for / f“跳过”近端不起作用。有人可以解释这里有什么问题吗？谢谢！

@echo off
SETLOCAL EnableDelayedExpansion

Set "logfile=abc.log"

rem ~ Get line count and exit if not greater 100
  For /f %%G in ('Type "!logfile!"^|Find "" /v /c') Do SET /a linecount=%%G
  If not %linecount% GTR 100 exit /b

rem ~ get number lines to skip
  set /a skiplines=!linecount! -100
  echo. &echo logfile=%logfile%, linecount=%linecount%, skiplines=%skiplines%
  :: Above displays: logfile=abc.log, linecount=243, skiplines=143

::这就是问题：

rem ~ skip the first %skiplines% in file and write remaining to temp
  for /f "skip=!skiplines! delims=*" %%H in ("!logfile!") do echo %%H >>newfile.tmp

::上面给出错误：“！skiplines！delims = *”此时出乎意料。“

  for /f "skip=%skiplines% delims=*" %%H in ("!logfile!") do echo %%H >>newfile.tmp

:(正如预期的那样，将0写入newfile.tmp）

一种解决方案 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

我正在编辑以突出显示这个单行解决方案以及已接受的答案。代码需要usebackq，包含在@Magoo中。这有效：

for /f "usebackqskip=%skiplines% delims=*" %%H in ("!logfile!") do echo %%H>>newfile.tmp

Answer 1

问题是在此过程中评估!var!和%var%的时间。 %var%首先被评估（替换），但!var!仅在建立循环条件后评估，因此不期望!var!位置。

解决方案是仅按预期使用!var!（在循环内），其中值在运行时确定，而不是在解析时确定。使用%var%访问分析时间值。不要将!var!和%var%视为循环之外的等价物。对于命令他们实际上是，但不是全部。

顺便说一句 - 看看linecount是否真的发生了什么。SKIP不喜欢0.如果我是你，我会将GTR更改为GEQ ...

这是一个应该展示正在发生的事情的例程。它使用我的工作区 - 毫无疑问，你需要为你的系统改变它。

@ECHO OFF SETLOCAL :: Just setting up data SET "sourcedir=U:\sourcedir" Set "logfile=abc.log" PUSHD "%sourcedir%" ( FOR /l %%a iN (1,1,99) DO ECHO line %%a )>"%logfile%" CALL :process >>"%logfile%" ECHO line 100 CALL :process >>"%logfile%" ECHO line 101 CALL :process >>"%logfile%" ECHO line 102 CALL :process popd GOTO :eof :process For /f %%G in ('type "%sourcedir%\%logfile%"^|Find "" /v /c') Do SET /a linecount=%%G ECHO %linecount% lines IN log file IF %linecount% leq 100 EXIT /b ECHO MORE than 100 lines!! SET /a skiplines=linecount - 100 SET /a skiplines2=%linecount% - 100 ECHO ------- observe response from this instruction SET /a skiplines3=!linecount! - 100 ECHO ------- this is because of the sequence-of-evaluation-and-substitution SET skipline :: delete the output file DEL newfile.tmp >NUL 2>NUL FOR /f "usebackqskip=%skiplines% delims=*" %%H IN ("%sourcedir%\%logfile%") DO ECHO %%H >>newfile.tmp ECHO ===================== ECHO after skipping %skiplines% of %logfile% result is TYPE newfile.tmp ECHO ===================== EXIT /b

结果应为

99 lines IN log file 100 lines IN log file 101 lines IN log file MORE than 100 lines!! ------- observe response from this instruction Missing operator. ------- this is because of the sequence-of-evaluation-and-substitution skiplines=1 skiplines2=1 skiplines3=0 ===================== after skipping 1 of abc.log result is line 2 line 3 ... line 100 line 101 ===================== 102 lines IN log file MORE than 100 lines!! ------- observe response from this instruction Missing operator. ------- this is because of the sequence-of-evaluation-and-substitution skiplines=2 skiplines2=2 skiplines3=0 ===================== after skipping 2 of abc.log result is line 3 line 4 ... line 101 line 102 =====================

Answer 2

可能是因为您的文件位于!logfile!，而不是!countfile!。％skiplines％应该有效，因为它没有在设置的同一语句中使用。

如何使用/ f跳过从文本文件的开头删除行

2 个答案: