sudo -i passes on the DISPLAY environment variable

[Skaperen]

the "sudo -i" command passes on the DISPLAY environment variable, by default. shouldn't it also pass on these:



XDG_CONFIG_DIRS
XDG_CURRENT_DESKTOP
XDG_DATA_DIRS
XDG_GREETER_DATA_DIR
XDG_MENU_PREFIX
XDG_RUNTIME_DIR
XDG_SEAT
XDG_SEAT_PATH
XDG_SESSION_DESKTOP
XDG_SESSION_ID
XDG_SESSION_PATH
XDG_SESSION_TYPE
XDG_VTNR

[TheFu]

I'm not seeing that on 16.04 Server that I ssh into.


thefu@vpn:~$ env|grep DISPL
thefu@vpn:~$
thefu@vpn:~$ sudo -i
root@vpn:~# env|grep DISPL
root@vpn:~#

I am seeing it on a local 16.04 desktop.

$ env|grep DIS
HOSTDISPLAY=posc:0
DISPLAY=:0
thefu@posc:/misc$ sudo -i
root@posc:~# env|grep DIS
DISPLAY=:0

[Skaperen]

since the server doesn't have DISPLAY set at all, there is nothing for sudo to pass on.

[TheFu]

thefu@vpn:~$ env|grep SSH
SSH_CLIENT=172.22.22.13 36614 22
SSH_TTY=/dev/pts/0
SSH_CONNECTION=172.22.22.13 36614 172.22.22.9 22

thefu@vpn:~$ sudo -i
root@vpn:~# env|grep SSH

So just DISPLAY? I suspect there is an explanation ... checking the manpage:

-i, --login
Run the shell specified by the target user's password dataâ
base entry as a login shell. This means that login-specific
resource files such as .profile or .login will be read by the
shell. If a command is specified, it is passed to the shell
for execution via the shell's -c option. If no command is
specified, an interactive shell is executed. sudo attempts
to change to that user's home directory before running the
shell. The command is run with an environment similar to the
one a user would receive at log in. The Command environment
section in the sudoers(5) manual documents how the -i option
affects the environment in which a command is run when the
sudoers policy is in use.

and inside the sudoers manpage:

As a special case, if sudo's -i option (initial login) is specified,
sudoers will initialize the environment regardless of the value of
env_reset. The DISPLAY, PATH and TERM variables remain unchanged; HOME,
MAIL, SHELL, USER, and LOGNAME are set based on the target user. On AIX
(and Linux systems without PAM), the contents of /etc/environment are
also included. All other environment variables are removed.


There you have it. Documented and working as designed.

[Skaperen]

do you think the SSH variables should be added to the list of what is passed along?