症状：

root@gs:~# dpkg-reconfigure locales
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = "en_US:",
LC_ALL = (unset),
LANG = "zh_CN.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
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_ALL to default locale: No such file or directory
Generating locales...
  en_AG.UTF-8... up-to-date
  en_AU.UTF-8... up-to-date
  en_BW.UTF-8... up-to-date
  en_CA.UTF-8... up-to-date
  en_DK.UTF-8... up-to-date
  en_GB.UTF-8... up-to-date
  en_HK.UTF-8... up-to-date
  en_IE.UTF-8... up-to-date
  en_IN.UTF-8... up-to-date
  en_NG.UTF-8... up-to-date
  en_NZ.UTF-8... up-to-date
  en_PH.UTF-8... up-to-date
  en_SG.UTF-8... up-to-date
  en_US.UTF-8... up-to-date
  en_ZA.UTF-8... up-to-date
  en_ZM.UTF-8... up-to-date
  en_ZW.UTF-8... up-to-date
  zh_CN.UTF-8... done
Generation complete.

解决办法：

root@gs:~# echo "export LC_ALL=C" >> /root/.bashrc
root@gs:~# source /root/.bashrc
root@gs:~# sudo dpkg-reconfigure locales

搞定