分配非数组变量时的文件名扩展

Question

这是关于 Zsh 5.5.1 的。

假设我有一个扩展到一个文件的 glob 模式，我想将这个文件分配给一个变量。这有效：

# N: No error if no files match. D: Match dot files. Y1: Expand to exactly one entry.
myfile=(*(NDY1))

和 echo $myfile 将显示文件（或目录）。但是这个不行：

myfile=*(NDY1)

在后一种情况下，echo $myfile 保持模式，即 *(NDY1)。

当然我可以做一些便宜的把戏，比如通过

创建一个chilprocess

myfile=$(echo *(NDY1))

但是有没有办法不用这些技巧就可以进行assinment？

Answer 1

默认情况下，zsh 不会在标量分配中进行文件名扩展，但选项 GLOB_ASSIGN 可以提供帮助。（提供此选项只是为了向后兼容。）

local myfile=''
() {
  setopt localoptions globassign
  myfile=*(NDY1)
}
echo $myfile
;#>> something

以下是 zsh 文档中的一些描述：

The value of a scalar parameter may also be assigned by writing:
name=value
In scalar assignment, value is expanded as a single string, in which the elements of arrays are joined together; filename expansion is not performed unless the option GLOB_ASSIGN is set.

--- zshparam(1), Description, zsh parameters

GLOB_ASSIGN <C>
If this option is set, filename generation (globbing) is performed on the right hand side of scalar parameter assignments of the form 'name=pattern (e.g. foo=*'). If the result has more than one word the parameter will become an array with those words as arguments. This option is provided for backwards compatibility only: globbing is always performed on the right hand side of array assignments of the form name=(value) (e.g. foo=(*)) and this form is recommended for clarity; with this option set, it is not possible to predict whether the result will be an array or a scalar.

--- zshoptions(1), GLOB_ASSIGN, Expansion and Globbing, Description Of Options, zsh options

分配非数组变量时的文件名扩展

filename expansion on assigning a non-array variable

zsh