从 bash 变量中删除非打印字符
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Remove non printing chars from bash variable
提问by Stepan Loginov
I have some variable $a. This variable have non printing characters (carriage return ^M).
我有一些变量$a。此变量具有非打印字符（回车 ^M）。
>echo $a
some words for compgen
>a+="END"
>echo $a
ENDe words for compgen
How I can remove that char?
I know that echo "$a"display it correct. But it's not a solution in my case.
我怎样才能删除那个字符？我知道echo "$a"显示正确。但这不是我的情况的解决方案。
采纳答案by chepner
To remove just the trailing carriage return from a, use
要仅从 中删除尾随回车a，请使用
a=${a%$'\r'}
回答by devnull
You could use tr:
你可以使用tr：
tr -dc '[[:print:]]' <<< "$var"
would remove non-printable character from $var.
将从中删除不可打印的字符$var。
$ foo=$'abc\rdef'
$ echo "$foo"
def
$ tr -dc '[[:print:]]' <<< "$foo"
abcdef
$ foo=$(tr -dc '[[:print:]]' <<< "$foo")
$ echo "$foo"
abcdef
回答by We Are All Monica
I was trying to send a notification via libnotify, with content that may contain unprintable characters. The existing solutions did not quite work for me (using a whitelist of characters using trworks, but strips any multi-byte characters).
我试图通过 libnotify 发送通知，其内容可能包含不可打印的字符。现有的解决方案对我来说不太适用（使用tr作品的字符白名单，但去除任何多字节字符）。
Here is what worked, while passing the test:
通过测试时，这是有效的：
message=$(iconv --from-code=UTF-8 -c <<< "$message")
