如何在su-中保留环境变量？

我发现su有一个保存环境的选项：

-m, -p, --preserve-environment
           Preserve the current environment, except for:
...

这样，将执行目标用户的shell初始化文件，就像执行登录shell一样，但是如果任何LC_xxx变量已经包含有效值，则可以对其进行测试并且不对其进行初始化。

编辑：只是注意，我能够通过添加一个脚本/etc/profile.d/ssh_lc_vars.sh处理导出的LC_xxx变量，从而在整个系统中应用。我还必须对未处理的未初始化环境变量做一些额外的工作su -ml userxxx。以下是更多示例，因为我无法包含整个脚本。如果有人可以改进它，那就更好了。

...
# clean up client-side variable for junk
lc_sanitize()
{
   arg="$1"
   # first, strip underscores
   clean="${arg//_/}"

   # next, replace spaces with underscores
   clean="${clean// /_}"

   # now, clean out anything that's not alphanumeric, underscore, hypen or dot
   ret="${clean//[^a-zA-Z0-9_\.-]/}"

   # return santized value to caller
   echo "$ret"
}

# LC_MY_LANG comes from an ssh client environment. If empty,
# this isn't a remote ssh user, but set it locally so this user
# can connect elsewhere where this script runs
if [ -z "$LC_MY_LANG" ]; then
   # force an LC_xxx setting for the environment
    LC_MY_LANG="en-US.utf-8"
else
    # otherwise, use the LC_xxxx variable from the ssh environment
    # 2017-01-30 - when using "su --preserve-environment  userxxx --login" be sure to fixup needed variables
    # shorthand: su -ml user111
    export USER=`whoami`
    export LOGNAME=${USER}
    export HOME=$( getent passwd "$USER" | cut -d: -f6 )
    cd ${HOME}

    # sanitize variable which was set client-side and log it
    u_sanitized=$(lc_sanitize "$LC_MY_LANG")
    echo "Notice: LC_MY_LANG sanitized to $u_sanitized from $SSH_CLIENT as user $USER" | logger -p auth.info
fi

# mark variable read-only so user cannot change it then export it
readonly LC_MY_LANG
# set terminal to LC_MY_LANG
export LC_LANG=${LC_MY_LANG}
export LC_MY_LANG
...