bash 如何为读取命令添加换行符？
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How do I add a line break for read command?
提问by Strawberry
read -p "Please Enter a Message:" message
How can I add a line break after Message:?
如何在之后添加换行符Message:？
采纳答案by T.J. Crowder
I like Huang F. Lei's answer, but if you don't like the literal line break, this works:
我喜欢Huang F. Lei 的回答，但如果你不喜欢文字换行，这有效：
read -p "Please Enter a Message: `echo $'\n> '`" message
Shows:
节目：
Please Enter a Message: > _
...where _is where the cursor ends up. Note that since trailing newlines are usually dropped during command substitution, I've included the >afterward. But actually, your original question doesn't seem to want that prompt bit, so:
...哪里_是光标结束的地方。请注意，由于尾随换行符通常在命令替换过程中被删除，因此我包含了后面的换行符>。但实际上，你最初的问题似乎并不想要那个提示，所以：
# Get a carriage return into `cr` -- there *has* to be a better way to do this
cr=`echo $'\n.'`
cr=${cr%.}
# Use it
read -p "Please Enter a Message: $cr" message
Shows
节目
Please Enter a Message: _
There has to be a better way, though.
不过，必须有更好的方法。
回答by ferhtgoldaraz
Just looking for the exact same thing. You can use:
只是在寻找完全相同的东西。您可以使用：
# -r and -e options are unrelated to the answer.
read -rep $'Please Enter a Message:\n' message
And it will work exactly as asked:
它将完全按照要求工作：
Please enter a Message:
_
Here is an extract from the bash manpage explaining it:
这是 bash 联机帮助页的摘录，对此进行了解释：
Words of the form $'string' are treated specially. The word expands to string, with backslash-escaped characters replaced as specified by the ANSI C standard. Backslash escape sequences, if present, are decoded as follows:
- (...)
- \n new line
- (...)
The expanded result is single-quoted, as if the dollar sign had not been present.
$'string' 形式的词被特殊处理。单词扩展为字符串，并按照 ANSI C 标准的规定替换反斜杠转义字符。反斜杠转义序列（如果存在）按如下方式解码：
- （……）
- \n 换行
- （……）
扩展结果是单引号的，就好像美元符号不存在一样。
Took me a while to find out.
我花了一段时间才知道。
Note that single quotes and double quotes behave differently in this regard:
请注意，单引号和双引号在这方面的表现不同：
A double-quoted string preceded by a dollar sign ($) will cause the string to be translated according to the current locale. If the cur- rent locale is C or POSIX, the dollar sign is ignored. If the string is translated and replaced, the replacement is double-quoted.
以美元符号 ($) 开头的双引号字符串将使字符串根据当前区域设置进行翻译。如果当前语言环境是 C 或 POSIX，则忽略美元符号。如果字符串被翻译和替换，则替换是双引号。
回答by augurar
Here's an improvement on the accepted answer that doesn't require spawning a subshell:
这是对不需要生成子shell的已接受答案的改进：
read -p "Please Enter a Message:"$'\n' message
From the GNU Bash reference manual:
Words of the form
$'string'are treated specially. The word expands to string, with backslash-escaped characters replaced as specified by the ANSI C standard.
表格
$'string'中的词被特殊处理。该单词扩展为string，并按照 ANSI C 标准的规定替换反斜杠转义字符。
回答by Huang F. Lei
$ read -p "Please Enter a Message:
> " message
Please Enter a Message:
Typing a "newline" between ':' and '"' directly.
直接在 ':' 和 '"' 之间键入“换行符”。
回答by Luca Borrione
Just to improve the answers of Huang F. Leiand of T.J. Crowderwhich I like (and added +1) .. You can use one of the following syntaxes too, which basically are the same, it depends on your taste (I prefer the first one):
只是为了改进我喜欢的Huang F. Lei和TJ Crowder的答案（并添加了 +1）.. 您也可以使用以下语法之一，它们基本上是相同的，这取决于您的口味（我更喜欢第一）：
read -p "$(echo -e 'Please Enter a Message: \n\b')" message
read -p "`echo -e 'Please Enter a Message: \n\b'`" message
which both will produce the following output:
这两者都会产生以下输出：
Please Enter a Message:
_
where _ is the cursor.
In case you need a newline in any part of the string but the end, you can use \n, for example
其中 _ 是光标。
如果您需要在字符串的任何部分但结尾处有一个换行符，您可以使用\n，例如
read -p "`echo -e '\nPlease Enter\na Message: '`" message
will produce
会产生
.
Please Enter
a Message: _
where . is a blank first new line and _ is the cursor.
Only to add a final trailing newline you have to use \n\bas in my first example
在哪里 。是一个空白的第一个新行，_ 是光标。
仅添加最后一个尾随换行符，您必须\n\b像在我的第一个示例中一样使用
回答by Alnitak
From the bashmanpage:
从bash联机帮助页：
-p prompt
Display prompt on standard error, without a trailing new-
line, before attempting to read any input. The prompt is
displayed only if input is coming from a terminal.
So, not with readitself, and putting \nin the message string just echoes \n. The answer should be simple though - don't get readto display the prompt:
所以，不是与read它自己，而是放入\n消息字符串只是 echo \n。答案应该很简单 - 不要read显示提示：
echo "Please Enter a Message:" 1>&2
read message
回答by Ruggero Turra
read -p "Please Enter a Message:Return" message
read -p "Please Enter a Message:Return" message
