案例１：
在debian下安装程序时，有时候会因为本地设置没有设置好，Per会给出下面的错误提示：

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
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

要解决这个问题，其实很简单，只要执行下面几条命令，一切都会OK：

debian:~# apt-get install locales
debian:~# dpkg-reconfigure locales
debian:~# locale

一切都会OK? 不一定，看下面的帖子。

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http : // askubuntu.com/questions/162391/how-do-i-fix-my-locale-issue

How do I fix my locale issue?

通用的第一招：

First run locale to list what locales currently defined for the current user account:

$ locale

LANG=C

LANGUAGE=

LC_CTYPE=fi_FI.UTF-8

LC_NUMERIC="C"

LC_TIME="C"

LC_COLLATE=fi_FI.UTF-8

LC_MONETARY="C"

LC_MESSAGES=fi_FI.UTF-8

LC_PAPER="C"

LC_NAME="C"

LC_ADDRESS="C"

LC_TELEPHONE="C"

LC_MEASUREMENT="C"

LC_IDENTIFICATION="C"

LC_ALL=

Then generate the missing locale and reconfigure locales to take notice:

$ sudo locale-gen "en_US.UTF-8"

Generating locales...

  en_US.UTF-8... done

Generation complete.

$ sudo dpkg-reconfigure locales

Generating locales...

  en_US.UTF-8... up-to-date

Generation complete.

Now you will not see any errors anymore!

如果第一招不灵：

比如Umair 反馈说：　did not work for me – Umair

 Ivan Buttinoni又支了一招

@UmairAyub may be you have more than one unknow locale, try this: for y in $(locale | cut -d '=' -f 2| sort |uniq );do locale-gen $y; done It will generate a locale for each definition you have – Ivan Buttinoni 

另外，设置环境变量也可以解决这个问题：

putting to the file /etc/environment:

LC_ALL=en_US.UTF-8

LANG=en_US.UTF-8

或者更新到/etc/default/locale

sh -c "echo -e 'LANG=en_US.UTF-8\nLC_ALL=en_US.UTF-8' > /etc/default/locale"

如果是在远程连接时报的这个错误，可以使用下面的方法：

This is a common problem if you are connecting remotely, so the solution is to not forward your locale. Edit /etc/ssh/ssh_config and comment out SendEnv LANG LC_* line.

On OSX (connecting to ubuntu) it's at /etc/ssh_config

One-liner to do this: sed -e '/SendEnv/ s/^#*/#/' -i /etc/ssh/ssh_config (useful for server provisioning) 

update-locale命令做了什么？

here is a command for that:

sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8

It updates /etc/default/locale with provided values.

dpkg-reconfigure locales可能什么返回都没有，需要安装语言包：

What worked for me on 12.10 was this:

apt-get install language-pack-en-base  

This was after dpkg-reconfigure locales produced no results.

其他还有很多补充，比如使用ＫＤＥ时怎么办．