Shell does not support UTF-8 about busybox HOT 7 CLOSED

$ docker run -it --rm busybox
/ # echo '?'
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/ # echo -e "\xE2\x98\xA0"
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CONFIG_SUBST_WCHAR:                                               

Typical values are 63 for '?' (works with any output device),     
30 for ASCII substitute control code,                             
65533 (0xfffd) for Unicode replacement character.                 

Symbol: SUBST_WCHAR [=63]                                         
Prompt: Character code to substitute unprintable characters with  
  Defined at Config.in:186                                        
  Depends on: UNICODE_SUPPORT                                     
  Location:                                                       
    -> Busybox Settings                                           
      -> General Configuration                                    
        -> Support Unicode (UNICODE_SUPPORT [=y])                 

CONFIG_LAST_SUPPORTED_WCHAR:                                                                        

Any character with Unicode value bigger than this is assumed                                        
to be non-printable on output device. Many applets replace                                          
such chars with substitution character.                                                             

The idea is that many valid printable Unicode chars are                                             
nevertheless are not displayed correctly. Think about                                               
combining charachers, double-wide hieroglyphs, obscure                                              
characters in dozens of ancient scripts...                                                          
Many terminals, terminal emulators, xterms etc will fail                                            
to handle them correctly. Choose the smallest value                                                 
which suits your needs.                                                                             

Typical values are:                                                                                 
126 - ASCII only                                                                                    
767 (0x2ff) - there are no combining chars in [0..767] range                                        
              (the range includes Latin 1, Latin Ext. A and B),                                     
              code is ~700 bytes smaller for this case.                                             
4351 (0x10ff) - there are no double-wide chars in [0..4351] range,                                  
              code is ~300 bytes smaller for this case.                                             
12799 (0x31ff) - nearly all non-ideographic characters are                                          
              available in [0..12799] range, including                                              
              East Asian scripts like katakana, hiragana, hangul,                                   
              bopomofo...                                                                           
0 - off, any valid printable Unicode character will be printed.                                     

Symbol: LAST_SUPPORTED_WCHAR [=767]                                                                 
Prompt: Range of supported Unicode characters                                                       
  Defined at Config.in:195                                                                          
  Depends on: UNICODE_SUPPORT                                                                       
  Location:                                                                                         
    -> Busybox Settings                                                                             
      -> General Configuration                                                                      
        -> Support Unicode (UNICODE_SUPPORT [=y])