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I have some variable $a. This variable have non printing characters (carriage return ^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.
310
Step 1: Click on any cell (D3). Enter Formula =CLEAN(C3). Step 2: Click ENTER. It removes non-printable characters.
So as far as I can tell, %% doesn't have any special meaning in a bash function name. It would be just like using XX instead. This is despite the definition of a name in the manpage: name A word consisting only of alphanumeric characters and under- scores, and beginning with an alphabetic character or an under- score.
To remove the last n characters of a string, we can use the parameter expansion syntax ${str::-n} in the Bash shell. -n is the number of characters we need to remove from the end of a string.
The tr command (short for translate) is used to translate, squeeze, and delete characters from a string. You can also use tr to remove characters from a string. For demonstration purposes, we will use a sample string and then pipe it to the tr command.
You could use tr:
tr -dc '[[:print:]]' <<< "$var"
would remove non-printable character from $var.
$ foo=$'abc\rdef'
$ echo "$foo"
def
$ tr -dc '[[:print:]]' <<< "$foo"
abcdef
$ foo=$(tr -dc '[[:print:]]' <<< "$foo")
$ echo "$foo"
abcdef
To remove just the trailing carriage return from a, use
a=${a%$'\r'}
I was trying to send a notification via libnotify, with content that may contain unprintable characters. The existing solutions did not quite work for me (using a whitelist of characters using tr works, but strips any multi-byte characters).
Here is what worked, while passing the 💩 test:
message=$(iconv --from-code=UTF-8 -c <<< "$message")
As an equivalent to the tr approach using only shell builtins:
cleanVar=${var//[![:print:]]/}
...substituting :print: with the character class you want to keep, if appropriate.
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