为什么回声会产生换行符？

Question

What's the difference between

echo -n "
> "

and

echo -n ""

The first one produces a newline whereas the second doesn't.

I'm running GNU bash, version 4.2.45(1)-release (x86_64-pc-linux-gnu)

Edit : I get that the input gets a newline here. I should have been clearer with the question. Consider the following script input.sh

#!/bin/bash
echo -n $1

The following doesn't produce a newline.

./input.sh "
> "

Answer 1

The string

"
 > "

has a newline in it as far as bash is concerned. The -n flag just means that echo will not print an extra newline at the end of your output. It will still reproduce your input, including newlines.

Answer 2

Expanding on @chepner's comment. Consider this:

$ set -- "
"

$ echo -n "$1" | od -c
0000000  \n
0000001

$ echo -n $1 | od -c
0000000

When you leave the variable unquoted, any leading or trailing sequences of whitespace are removed by shell. So bash discards your newline when you don't quote $1. This happens before "echo" is invoked, so "echo -n" is given no arguments .

From the Word Splitting section in the manual:

If IFS is unset, or its value is exactly <space><tab><newline> , the default, then sequences of <space> , <tab> , and <newline> at the beginning and end of the results of the previous expansions are ignored, and any sequence of IFS characters not at the beginning or end serves to delimit words.