批量跳过WMIC命令输出的最后一个空行 [英] Skipping last empty line of WMIC command output in batch

问题描述

我正在尝试以JSON格式格式化命令的输出:

I am trying to format the output of a command in JSON as such:

echo "patches" : {
set patches="wmic qfe get HotfixID"
for /f "skip=1" %%i in (' %patches% ') do (
    set /a count=count+1
    call echo "!count!" : "%%i",
)
echo }

一切都很好，直到我打到补丁列表的末尾，它会读取最后一个补丁之后的行，然后打印"".

Everything is fine until I hit the end of the list of patches where it reads the line after the last patch and then prints "".

我应该如何使它停止?

如果可能的话，我想避免使用文本文件.

If possible, I would like to avoid using text files.

推荐答案

在for /f循环内，放置另一个:

Inside the for /f loop, place another one:

for /f "skip=1" %%i in ('%patches%') do for /f "delims=" %%j in ("%%i") do (
    rem // use `%%j` in the loop body
)

wmic命令返回Unicode输出.由于for /f并不适合处理此类问题，因此会产生诸如孤立的回车(CR)之类的伪像，从而导致您遇到的效果(由于for /f %%i循环中包含此类CR，最后一行并不会显示为空；请记住，for /f会跳过真正为空的行).在内部放置另一个for /f循环，然后对每个项目进行重复处理可消除此类伪像.

The wmic command returns Unicode output. Since for /f is not perfect for handling such, it produces artefacts like orphaned carriage-returns (CR), leading to the effect you encounter (the last line does not appear empty to your for /f %%i loop as it contains such a CR; remember that for /f skips lines that are really empty). Placing another for /f loop inside and hence double-processing each item removes such artefacts.

这是固定的脚本:

echo "patches" : {
set "patches=wmic qfe get HotfixID"
for /f "skip=1" %%i in ('%patches%') do for /f "delims=" %%j in ("%%i") do (
    set /a count=count+1
    echo "!count!" : "%%j",
)
echo }

由于我没有得到call命令的目的，因此我将其删除了.

Since I did not get the purpose of the call command, I simply removed it.

双重解析方法实际上归功于 dbenham －请参见他对 WMIC和FOR/F:针对尾随< CR>问题.

The double-parsing method is actually credited to dbenham -- see his answer to Why is the FOR /f loop in this batch script evaluating a blank line? and also his external article WMIC and FOR /F : A fix for the trailing <CR> problem.

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