xargs错误地将我的src目录复制到一个tgt目录 [英] xargs is incorrectly copying my src dir to one tgt directory

问题描述

此问题基于

This question builds off of a previous question. I do not want to edit the previous question because then I would be introducing a new complexity to a question that already has SO many comments. It would skew the context of the current answers.

以下是名为mapping.txt

src/a/  tgt/aye/
src/b   tgt/b/
src/c/  tgt/c

源文件结构如下

/tmp/testzone/src/a/afile.txt
/tmp/testzone/src/b/bfile.txt
/tmp/testzone/src/c/cfile.txt

我们要做的第一件事是基于mapping.txt文件创建目标目录文件夹结构

First thing we do is create the target directory folder structure based on the mapping.txt file

cut -f 2 mapping.txt | tr '\n' '\0' | xargs -0 mkdir -p

哪个将创建目标目录文件夹结构

Which creates the target directory folder structure

/tmp/testzone/tgt/aye/
/tmp/testzone/tgt/b/
/tmp/testzone/tgt/c/

接下来我们运行

 xargs --arg-file mapping2.txt cp -a

似乎将源目录的内容放入目标目录的c目录中.这是错误的.它应该使用mapping.txt文件逐行从源复制到目标.

Which seems to put the source directory contents into the target directory's c directory. This is wrong. It should be using the mapping.txt file to copy from source to target line by line.

/tmp/testzone/tgt/aye/
/tmp/testzone/tgt/b/
/tmp/testzone/tgt/c/a/afile.txt
/tmp/testzone/tgt/c/aye/
/tmp/testzone/tgt/c/b/bfile.txt
/tmp/testzone/tgt/c/c/cfile.txt

什么可能导致此问题?

推荐答案

在没有其他指示的情况下，xargs会将输入文件中尽可能多的行作为参数放在单个cp调用中.这就是设计 要做的.

In the absence of options to instruct it otherwise, xargs will put as many lines of possible from the input file as arguments to a single cp invocation. This is what xargs was designed to do.

您可能会找到一种向正确方向轻推的方法，但这似乎只是您应该做的

You can probably find a way to nudge it in the right direction, but this looks like you should simply be doing

while read -r src dst; do
    mkdir -p "${dst%/*}"
    cp -a "$src" "$dst"
done<mapping2.txt

也许已经在注释中建议了install来进一步简化此操作.

Maybe look at install to further simplify this, as already suggested in a comment.

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