Question

我想在变量扩展后添加文本，但是fish认为我指的是一个不同的变量名称，例如。

$ set dessert "cake"
$ echo $dessert
cake
$ echo "I want 7 $desserts"
I want 7 
$ cat ./menu.txt | sed "s/$desserts/cookie/g"
sed: first RE may not be empty

Answer 1

看起来你想把大括号放在你的vaiable周围，比如＆＃34; {$ dessert} s。＆＃34; 例如：

> set xyz blarch
> echo $xyz
blarch
> echo ${xyz}
Variables cannot be bracketed. In fish, please use {$xyz}.
fish: echo ${xyz}
            ^
> echo {$xyz}
blarch
> echo i like {$xyz}s
i like blarchs
>

编辑2：嗯...奖金鱼扩张r.e. @glenn jackman的例子：以这种方式安排以更容易地看到输出差异：

        example fish command                     ::    result
-------------------------------------------------::------------------------
> set foo bar; echo shakespere was a {$foo}      :: shakespere was a bar
> set foo bar; echo shakespere was a {$foo}d     :: shakespere was a bard
> set foo bar; echo "shakespere was a {$foo}d"   :: shakespere was a {bar}d
> set foo bar; echo "shakespere was a {"$foo"}d" :: shakespere was a {bar}d
> set foo bar; echo "shakespere was a "{$foo}"d" :: shakespere was a bard
> set foo bar; echo "shakespere was a "$foo"d"   :: shakespere was a bard
>

似乎最后一个效率最高。

编辑：我想说的是，与其他shell相比，Fish与var扩展有点不同，比如bash。请注意行为，{$ xyz}不会失败，但它的工作方式与Fish相同......而{}被视为处理了{}＆＃39>文字在那里，它产生＆＃34; {moreblarch}＆＃34;像这样：

bash示例：

$ export xyz=moreblarch
$ echo $xyz
moreblarch
$ echo {$xyz}
{moreblarch}
$ echo ${xyz}
moreblarch
$ echo who doesnt like ${xyz}s?
who doesnt like moreblarchs?
$

编辑3：根据@ glennjackman的数组注释进行鱼类排列这不是我所期望的:-)＆＃34; echo -e＆＃34;将\ n解释为换行符，使其更容易查看输出。请注意，排列在它们之间插入了一个空格（这就是＃2 - ＃27具有前导空格的原因）。

> set a A B C; set b 1 2 3; set c x y z; echo -e ":a="$a" b="$b" c="$c":\n"
:a=A b=1 c=x:
 :a=B b=1 c=x:
 :a=C b=1 c=x:
 :a=A b=2 c=x:
 :a=B b=2 c=x:
 :a=C b=2 c=x:
 :a=A b=3 c=x:
 :a=B b=3 c=x:
 :a=C b=3 c=x:
 :a=A b=1 c=y:
 :a=B b=1 c=y:
 :a=C b=1 c=y:
 :a=A b=2 c=y:
 :a=B b=2 c=y:
 :a=C b=2 c=y:
 :a=A b=3 c=y:
 :a=B b=3 c=y:
 :a=C b=3 c=y:
 :a=A b=1 c=z:
 :a=B b=1 c=z:
 :a=C b=1 c=z:
 :a=A b=2 c=z:
 :a=B b=2 c=z:
 :a=C b=2 c=z:
 :a=A b=3 c=z:
 :a=B b=3 c=z:
 :a=C b=3 c=z:

>

变量扩展后添加文本 - 鱼

1 个答案: