Ubuntu18.04 doesn‘t support either C.UTF-8 or en_US.UTF-8

解决：

1.显示系统中没有en_us.utf8字符集
# locale -a 
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_COLLATE to default locale: No such file or directory
C
POSIX
zh_CN.utf8


2.下载英文字库：en_US.utf8
# sudo apt install language-pack-en
# sudo locale-gen en_US.utf8
# locale -a
C
POSIX
en_AG
en_AG.utf8
en_AU.utf8
en_BW.utf8
en_CA.utf8
en_DK.utf8
en_GB.utf8
en_HK.utf8
en_IE.utf8
en_IL
en_IL.utf8
en_IN
en_IN.utf8
en_NG
en_NG.utf8
en_NZ.utf8
en_PH.utf8
en_SG.utf8
en_US.utf8
en_ZA.utf8
en_ZM
en_ZM.utf8
en_ZW.utf8
zh_CN.utf8

3.下载中文字库：zh_cn.utf8
# sudo apt install language-pack-hans
# sudo locale-gen zh_CN.utf8