string bash：如何在字符串中添加空格？
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bash: How to add space in string?
提问by Marta Koprivnik
I have a string like this:
我有一个这样的字符串：
string="aaa-bbb"
But I want to add space before char '-', so I want this:
但我想在字符'-'之前添加空格，所以我想要这个：
aaa -bbb
I tried a lot of things, but I can't add space there. I tried with echo $string | tr '-' ' -', and some other stuff, but it didn't work...
我尝试了很多东西，但我无法在那里添加空间。我尝试过echo $string | tr '-' ' -'，以及其他一些东西，但没有奏效......
I have Linux Mint: GNU bash, version 4.3.8(1)
我有 Linux Mint：GNU bash，版本 4.3.8(1)
回答by Jeff Bowman
No need to call sed, use string substitutionnative in BASH:
无需调用sed，在 BASH 中使用原生字符串替换：
$ foo="abc-def-ghi"
$ echo "${foo//-/ -}"
abc -def -ghi
Note the two slashesafter the variable name: the first slash replaces the first occurrence, where two slashes replace every occurrence.
注意变量名后面的两个斜杠：第一个斜杠替换第一次出现，两个斜杠替换每次出现。
回答by Jay jargot
Give a try to this:
试试这个：
printf "%s\n" "${string}" | sed 's/-/ -/g'
It looks for -and replace it with -(space hyphen)
它查找-并替换为-（空格连字符）
回答by webb
trcan only substitute one character at a time. what you're looking for is sed:
tr一次只能替换一个字符。你要找的是sed：
echo "$string" | sed 's/-/ -/'
echo "$string" | sed 's/-/ -/'
回答by Stephen Quan
Bash has builtin string substitution.
Bash 具有内置的字符串替换功能。
result="${string/-/ -}"
echo "$result"
Alternatively you can use sed:
或者，您可以使用sed：
result=$(echo "$string" | sed 's/-/ -/')
echo "$result"
回答by Stephen Quan
You are asking the shell to echo an un-quoted variable $string.
When that happens, spaces inside variables are used to split the string:
您要求 shell 回显一个未加引号的变量$string。
发生这种情况时，变量内的空格用于拆分字符串：
$ string="a -b -c"
$ printf '<%s>\n' $string
<a>
<-b>
<-c>
The variable does contain the spaces, just that you are not seeing it correctly. Quote your expansions
该变量确实包含空格，只是您没有正确看到它。 引用您的扩展
$ printf '<%s>\n' "$string"
<a -b -c>
To get your variable changed from -to -there are many solutions:
要将变量从 更改-为-有很多解决方案：
sed: string="$(echo "$string" | sed 's/-/ -/g')"; echo "$string"
bash: string="${string//-/ -}; echo "$string"
sed: string="$(echo "$string" | sed 's/-/ -/g')"; echo "$string"
bash:string="${string//-/ -}; echo "$string"
