$ sudo update-initramfs -u
[sudo] password for marty:
update-initramfs: Generating /boot/initrd.img-3.2.0-29-generic-pae
Warning: No support for locale: en_US.utf8
$ sudo locale-gen --purge --no-archive 
Generating locales...
  en_AG.UTF-8... done
  en_AU.UTF-8... done
  en_BW.UTF-8... done
  en_CA.UTF-8... done
  en_DK.UTF-8... done
  en_GB.UTF-8... done
  en_HK.UTF-8... done
  en_IE.UTF-8... done
  en_IN.UTF-8... done
  en_NG.UTF-8... done
  en_NZ.UTF-8... done
  en_PH.UTF-8... done
  en_SG.UTF-8... done
  en_US.UTF-8... done
  en_ZA.UTF-8... done
  en_ZM.UTF-8... done
  en_ZW.UTF-8... done
Generation complete.
marty@xxxxxx:~
$ sudo update-initramfs -u
update-initramfs: Generating /boot/initrd.img-3.2.0-29-generic-pae

reference resources:

https://forums.linuxmint.com/viewtopic.php?f=42&t=111527 All kinds of answers from netizens