指定通配的结果在Bash中的变量 [英] Assign results of globbing to a variable in Bash

问题描述

我的同事，瑞安，来找我在他的Bash脚本中的错误，并且我与这个测试的问题：

My colleague, Ryan, came to me with a bug in his Bash script, and I identified the problem with this test:

$ mkdir ryan
$ mkdir ryan/smells-bad
$ FOO=ryan/smells-*
$ echo $FOO
ryan/smells-bad
$ touch $FOO/rotten_eggs
touch: cannot touch `ryan/smells-*/rotten_eggs': No such file or directory

由此我推断，通配echo命令过程中会发生，而不是在创建变量FOO。

From this I infer that the globbing happens during the echo command, not when the variable FOO is created.

我们有几个解决方法，按降序ungracefulness顺序：

We have a couple of workarounds, in descending order of ungracefulness:

touch `echo $FOO`/rotten_eggs

或者

pushd
cd $FOO
touch rotten_eggs
popd

但也不是令人满意的。我缺少一个把戏？

But neither is satisfying. Am I missing a trick?

推荐答案

的问题是，水珠就会仅在文件rotten_eggs的存在，展开，因为它包括在水珠图案。您应该使用数组。

The problem is that the glob will only expand if the file "rotten_eggs" exists, because it is included in the glob pattern. You should use an array.

FOO=( ryan/smells-* )
touch "${FOO[@]/%//rotten_eggs}"

该FOO数组包含一切的水珠匹配。使用％扩展追加/ rotten_eggs每个元素。

The FOO array contains everything matched by the glob. The expansion using % appends /rotten_eggs to each element.

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