--- /dev/null
+The version of sudo that ships with Debian by default resets the
+environment, as described by the "env_reset" flag in the sudoers file.
+
+This implies that all environment variables are removed, except for
+HOME, LOGNAME, PATH, SHELL, TERM, DISPLAY, XAUTHORITY, XAUTHORIZATION,
+LANG, LANGUAGE, LC_*, and USER.
+
+In case you want sudo to preserve more environment variables, you must
+specify the env_keep variable in the sudoers file. You should edit the
+sudoers file using the visudo tool.
+
+Examples:
+Preserve the default variables plus the EDITOR variable:
+
+ Defaults env_keep+="EDITOR"
+
+Preserve the default variables plus all variables starting with LC_:
+
+ Defaults env_keep+="LC_*"