在 bash shell 中打印星号（“*”）
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Printing asterisk ("*") in bash shell
提问by user2499325
a=5
echo "*/$aMin * * * * bash /etc/init.d/ckDskCheck.sh"
When I try to run the following code, it displays properly
当我尝试运行以下代码时，它显示正确
*/5 * * * * bash /etc/init.d/ckDskCheck.sh
But when I try to assign the result using the following code to the variable and print it out, it displays as this:
但是当我尝试使用以下代码将结果分配给变量并将其打印出来时，它显示为：
a=5
cronSen=`echo "*/$a * * * * bash /etc/init.d/ckDskCheck.sh"`
echo $cronSen
Result:
结果：
So I try to escape the asterisk by
所以我试图逃避星号
cronSen=`echo "\*/$a \* \* \* \* bash /etc/init.d/ckDskCheck.sh"`
But it still doesn't work. Why? How can I fix this?
但它仍然不起作用。为什么？我怎样才能解决这个问题？
回答by tripleee
You have two problems:
你有两个问题：
Useless Use of Echo in Backticks
Always quote what you
echo
反引号中 Echo 的无用使用
总是引用你的话
echo
So the fixed code is
所以固定代码是
a=5
cronSen="*/$a * * * * bash /etc/init.d/ckDskCheck.sh"
echo "$cronSen"
It appears you may also have a Useless Use of Variable, but perhaps cronSenis useful in a larger context.
看起来您可能也有一个 Useless Use of Variable，但可能cronSen在更大的上下文中很有用。
In short, quote everything where you do not require the shell to perform token splitting and wildcard expansion.
简而言之，引用不需要 shell 执行标记拆分和通配符扩展的所有内容。
Token splitting;
代币分裂；
words="foo bar baz"
for word in $words; do
:
(This loops three times. Quoting $wordswould only loop once over the literal token foo bar baz.)
（这循环了 3 次。引用$words只会在文字标记上循环一次foo bar baz。）
Wildcard expansion:
通配符扩展：
pattern='file*.txt'
ls $pattern
(Quoting $patternwould attempt to list a single file whose name is literally file*.txt.)
（引用$pattern将尝试列出名称为字面意思的单个文件file*.txt。）
In more concrete terms, anything containing a filename should usually be quoted.
更具体地说，通常应该引用任何包含文件名的内容。
A variable containing a list of tokens to loop over or a wildcard to expand is less frequently seen, so we sometimes abbreviate to "quote everything unless you know precisely what you are doing".
包含要循环的标记列表或要扩展的通配符的变量不太常见，因此我们有时缩写为“引用所有内容，除非您确切地知道自己在做什么”。
回答by cuonglm
You must use double quote when echo your variable:
回显变量时必须使用双引号：
echo "$cronSen"
If you don't use double quote, bashwill see *and perform filename expansion. *expands to all files in your current directory.
如果不使用双引号，bash将看到*并执行文件名扩展。*扩展到当前目录中的所有文件。
