Operating systems – Page 2 – Mikael Göransson

DisplayLink and Ubuntu 17.04 (intel)

I had a problem with DisplayLink drivers on my Dell Precision 5510 (XPS 15) after upgrading to Ubuntu 17.04.

The monitors connected to the DisplayLink device was enabled and identified, but the screens stayed all black.

Of course, there’s a solution. I found this evdi issue, containing a solution.

Create the file (and directory) /etc/X11/xorg.conf.d/20-intel.conf, with the content:

Section "Device"
  Identifier "Intel Graphics"
  Driver "Intel"
  Option "AccelMethod" "sna"
  Option "TearFree" "true"
  Option "TripleBuffer" "true"
  Option "MigrationHeuristic" "greedy"
  Option "Tiling" "true"
  Option "Pageflip" "true"
  Option "ExaNoComposite" "false"
  Option "Tiling" "true"
  Option "Pageflip" "true"
EndSection

Credit goes to github/ajbogh.

Make Thunderbird great again!

I have many times tried finding a modern replacement for Thunderbird, but it always ends without success.

There’s Nylas Mail, Hiri etc, but there has always been some needed feature (for me) missing.

Then I heard about Monterail, which basically is a functional theme based on a Thunderbird mock up. And just recently an Arc (theme) integration for Thunderbird has been released.

The two together makes Thunderbird quite pleasant to look at.

Dual boot Linux and Windows – BIOS system time incorrect

I, unfortunately, have to dual boot to Windows once and a while, due to requirements where I currently have an assignment.

What I’ve noticed and that really grind my gears, is that when booting Windows after I have been running Linux the BIOS System time is incorrect by -2 hours.

After searching for information how to solve this, I found a thread on the Microsoft forum with a user that had the same problem and learned something new:

Windows uses BIOS time to hold ‘local’ time (UTC+offset+daylight savings according to the time zone used) and Linux uses BIOS time to hold Universal Time (UTC).

That got me to the ever so good Arch Linux Wiki (this is an area that I think Ubuntu has become weaker in; updated and good information in a community wiki. Don’t get me wrong, I love askubuntu.com).

Open Windows Powershell and run it as administrator:

reg add "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\TimeZoneInformation" /v RealTimeIsUniversal /d 1 /t REG_DWORD /f

If this does not solve it, try changing REG_DWORD to REG_QWORD.

Take pictures during failed login attempts

Got the idea that I wanted to take some pictures if there’s a failed login attempt on my laptop. A quick google search and this is the way to do it:

Start off by creating a script that will use ffmpeg to takes a pictures using the webcam. I stored it in /usr/local/bin/failed-login.sh:

#!/usr/bin/env bash

DIR="${HOME}/Pictures/Failed Login"
FILE="failed-${HOSTNAME}-$(date +%Y%m%d-%H%M%S).jpg"

ffmpeg -loglevel panic \
    -f video4linux2 \
    -s vga \
    -i /dev/video0 \
    -vframes 1 \
    "${DIR}/${FILE}" >/dev/null

exit 0

In my actual case, I’m storing the pictures on my google drive.

If you have an webserver, it’s a nice feature to make the script upload the pictures there. This however will only work if you make sure that your most used wireless connections are marked with `All users may connect to this network` so you have internet access from the login screen. Also you need to have public key authentication setup for the user you’re going to use. The line below can then be added after the ffmpeg call:

{ scp -i /home/user/.ssh/id_rsa "${DIR}/$[FILE}" user@www.example.com:/var/www/pictures && rm "${DIR}/${FILE}"; } || true

Don’t forget to make it executable with chmod +x /usr/local/bin/failed-login.sh.

Run it manually and make sure that the pictures are stored in ${DIR}.

Last thing is just to modify /etc/pam.d/common-auth to run the script when there’s a failed login attempt. We’d want to change the following line:

auth   [success=1 default=ignore]      pam_unix.so nullok_secure

To:

auth   [success=2 default=ignore]      pam_unix.so nullok_secure

I.e. success=1 to success=2, this is to make sure that the script isn’t executed for a successful login.

After this line add the following:

auth    [default=ignore]                pam_exec.so seteuid /usr/local/bin/failed-login.sh

All in all, the file should look like this (without comments):

auth    [success=2 default=ignore]     pam_unix.so nullok_secure
auth    [default=ignore]                pam_exec.so seteuid /usr/local/bin/failed-login.sh
auth    requisite                       pam_deny.so
auth    required                        pam_permit.so
auth    optional                        pam_cap.so

Logout and enjoy the new feature of getting pictures of the offenders!

Pretty much everything is taken from this answer on askubuntu.com.

Citrix Receiver – use all available external monitors

When working on a remote server over Citrix, it is sometimes useful not having ICAClient to span over all monitors in fullscreen mode. It is possible to tell wfica to only span certain monitors with the -span parameter.

Change /opt/Citrix/ICAClient/wfica.sh to:

#!/bin/bash
ICAROOT=/opt/Citrix/ICAClient
export ICAROOT
LD_LIBRARY_PATH=/opt/Citrix/ICAClient/lib
export LD_LIBRARY_PATH

array_join() {
    local IFS="$1"
    shift
    echo "$*"
}

param=""
number_of_monitors="$(xrandr --query | grep -c " connected ")"

if (( number_of_monitors > 1 )); then
    param="-span"
    monitors=()
    for monitor in $(seq 2 "${number_of_monitors}"); do
        monitors+=("${monitor}")
    done

    param="${param} $(array_join ',' "${monitors[@]}")"
fi

$ICAROOT/wfica ${param} -file $1

This will use all monitors, except for the first one in fullscreen mode (unless you only have one monitor of course).

To get this to work automagically, Firefox has to be told to open *.ica files with this script. Go to Edit, Preferences, Applications, type ica in the search, select Use other... as action and browse to /opt/Citrix/ICAClient/wfica.sh.