[sudo-users] SIGHUP signal with sudoedit

[R. Diez]

Hi there:

I am trying to write a Bash script that uses sudo and sudoedit and I am 
getting signal SIGHUP from sudoedit. But let's start without a script, 
just running sudoedit manually. On Xubuntu 16.04.4, this is what I am 
getting:

----- Begin -----
$ sudoedit "$HOME/somefile.txt"; echo "sudoedit exit code: $?"
sudoedit: /home/rdiez/somefile.txt: editing files in a writable 
directory is not permitted
Hangup
sudoedit exit code: 129

$ bash --version
GNU bash, version 4.3.48(1)-release (x86_64-pc-linux-gnu)

$ sudo --version
Sudo version 1.8.16
Sudoers policy plugin version 1.8.16
Sudoers file grammar version 45
Sudoers I/O plugin version 1.8.16
----- End -----

On Ubuntu MATE 18.04, I get this instead:

----- Begin -----
$ sudoedit "$HOME/somefile.txt"; echo "sudoedit exit code: $?"
sudoedit: /home/rdiez/somefile.txt: editing files in a writable 
directory is not permitted
sudoedit exit code: 1

$ bash -version
GNU bash, version 4.4.19(1)-release (i686-pc-linux-gnu)

$ sudo --version
Sudo version 1.8.21p2
Sudoers policy plugin version 1.8.21p2
Sudoers file grammar version 46
Sudoers I/O plugin version 1.8.21p2
----- End -----

I would like to understand where the SIGHUP signal is coming from on 
Xubuntu 16.04.4, and who is actually printing the signal message. I 
actually noticed the first time around when the script called sudoedit 
and I did not modify the file. That signal comes then after the 
following message:

sudoedit: 
/var/lib/polkit-1/localauthority/10-vendor.d/49-my_personal_nopasswd_global.pkla 
unchanged

If I do modify the file after sudoedit opens up an editor, everything is 
OK, and the signal is not coming anymore.

It is all very strange. If I call sudoedit from within the script, I get 
something like this (the system is localized to Spain):

./nopass-polkit.sh: línea 109:  4466 Colgar (hangup)         sudoedit 
/var/lib/polkit-1/localauthority/10-vendor.d/49-my_personal_nopasswd_global.pkla

If I trap the signal within the Bash script, the trap code does not run 
(?), but the signal message gets shortened to "Colgar (hangup)". That is 
like when running sudoedit manually without a script.

I looked at .bashrc, unset EDITOR and SUDO_EDITOR, but the signal is 
still coming. Nothing else is trapping SIGHUP anywhere. I even started 
the Dash shell instead, and the behaviour is the same.

Can anybody help?

Thanks in advance,
   rdiez