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
LOGNAME, PATH, SHELL, TERM, DISPLAY, XAUTHORITY, XAUTHORIZATION, XAPPLRESDIR,
XFILESEARCHPATH, XUSERFILESEARCHPATH, 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_*"

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If you're using the sudo-ldap package, note that it is now configured to
look for /etc/sudo-ldap.conf. Depending on your system configuration, it
probably makes sense for this to be a symlink to /etc/ldap.conf, or perhaps
to /etc/libnss-ldap.conf or /etc/pam_ldap.conf. By default, no symlink or
file is provided, you'll need to decide what to do and create a suitable
file before sudo-ldap will work.

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As of version 1.7, sudo-ldap now requires the LDAP source to be specified
in /etc/nsswitch.conf with a line like:

sudoers: ldap

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Note that the support for the sss provider (libsss_sudo.so) that allows sudo
to use SSSD as a cache for policies stored in LDAP is included in the sudo
package, not in the sudo-ldap package. I have some hope that this turns out
to be a better overall solution for using sudo with LDAP, as the sudo-ldap
package is difficult to maintain and I'd love to be able to eliminate it!

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See the file OPTIONS in this directory for more information on the sudo
build options used in building the Debian package.

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If you're having trouble grasping the fundamental idea of what sudo is all
about, here's a succinct and humorous take on it...

http://www.xkcd.com/c149.html