Getting the lock screen to work reliably when resuming from suspension in a single-seat, multi-user Lubuntu 18.04 installation

In an earlier post I described my attempt at getting the lock screen to work reliably in the single-seat, multi-user Lubuntu 17.10 installation on my family’s desktop PC. Although the modifications described in that post seemed to improve matters somewhat, users were still not always able to login from the LightDM greeter screen after resuming from Suspend to RAM in the following situation:

  1. User_A logs in to User_A’s account but does not log out after using the account.
  2. User_B clicks on ‘Logout’ > ‘Switch User’ to log in to User_B’s account but does not log out.
  3. User_A clicks on ‘Logout’ > ‘Switch User’ to get back to User_A’s account.
  4. User_A allows his/her session to timeout and suspend to RAM.
  5. User_B presses a key on the keyboard to resume from suspension, and the LightDM lock screen is displayed.
  6. User_B enters his/her password and then clicks on ‘Unlock’, but the LightDM lock screen remains on display and nobody can log in any more, although the keys on the lock screen are still clickable.

When this occurs, the only way users can access their Desktop is to click on the Power icon in the top right corner of the lock screen and select ‘Restart…’.

The Software Updater in Lubuntu 17.10 recently offered me the choice of upgrading to Lubuntu 18.04, which I accepted. The upgrade was performed and the only hitch that resulted was an incorrect initramfs, which was simple enough to fix (see my post Lubuntu 18.04 ‘Gave up waiting for suspend/resume device’). However, the above-mentioned problem of unlocking after resuming from suspension still occurred in Lubuntu 18.04. Below are the changes I made since the modifications described in my post Getting the lock screen to work properly when resuming from Suspend-to-RAM with multiple sessions in Lubuntu 17.10 (the other changes in that post remain), which seem to have cured the problem.

Change to Item 2 in my earlier post

I reverted the Exec line in /etc/xdg/autostart/light-locker.desktop back to how it was originally following installation of Lubuntu:

user $ grep Exec /etc/xdg/autostart/light-locker.desktop
Exec=light-locker

Change to Item 3 in my earlier post

I deleted the file /lib/systemd/system-sleep/hang-fix that I had previously created:

user $ sudo rm /lib/systemd/system-sleep/hang-fix

Change to Item 7 in my earlier post

The Xfce Power Manager ‘Security’ tab for each user now has ‘Lock screen when system is going for sleep’ ticked:

Light Locker

  • Automatically lock the session: Never
  • Delay locking after screensaver for: ‘1 Seconds’ is greyed out
  • ‘Lock screen when system is going for sleep’ is ticked

The full Xfce Power Manager settings for each user (see the file ~/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-power-manager.xml in each user’s home directory) are now configured as follows:

<?xml version="1.0" encoding="UTF-8"?>

<channel name="xfce4-power-manager" version="1.0">
  <property name="xfce4-power-manager" type="empty">
    <property name="power-button-action" type="empty"/>
    <property name="show-tray-icon" type="empty"/>
    <property name="brightness-switch-restore-on-exit" type="int" value="1"/>
    <property name="brightness-switch" type="int" value="0"/>
    <property name="presentation-mode" type="bool" value="false"/>
    <property name="inactivity-on-ac" type="uint" value="15"/>
    <property name="blank-on-ac" type="int" value="10"/>
    <property name="dpms-on-ac-sleep" type="uint" value="0"/>
    <property name="dpms-on-ac-off" type="uint" value="0"/>
    <property name="brightness-on-ac" type="uint" value="9"/>
    <property name="lock-screen-suspend-hibernate" type="bool" value="true"/>
    <property name="logind-handle-lid-switch" type="bool" value="false"/>
    <property name="dpms-enabled" type="bool" value="false"/>
    <property name="general-notification" type="bool" value="true"/>
  </property>
</channel>

Additional modifications

In another of my posts (Prevent Lubuntu 17.10 from leaving an external HDD mounted incorrectly for other users) I explained the modifications I made in Lubuntu 17.10 for a single-seat, multi-user installation to work properly with a permanently connected external USB HDD. However, I recently noticed the following problems resulting from those modifications:

A. The following error message in the LightDM log file /var/log/lightdm/lightdm.log:

[SeatDefaults] is now called [Seat:*], please update this configuration

So I changed the contents of the file /etc/lightdm/lightdm.conf.d/10_lubuntu.conf from:

[SeatDefaults]
session-cleanup-script=/etc/lightdm/lightdm.conf.d/unmount_FREECOM_HDD.sh

to:

[Seat:*]
session-cleanup-script=/etc/lightdm/lightdm.conf.d/unmount_FREECOM_HDD.sh

B. The following error message in the LightDM log file/var/log/lightdm/lightdm.log when the USB external HDD happened to not be mounted at the time:

DEBUG: Launching process 8569: /etc/lightdm/lightdm.conf.d/unmount_FREECOM_HDD.sh
DEBUG: Process 8569 terminated with signal 11

So I changed the contents of my Bash script /etc/lightdm/lightdm.conf.d/unmount_FREECOM_HDD.sh from:

#!/bin/bash
udisksctl unmount --block-device /dev/disk/by-uuid/C6576A087368B015

to:

#!/bin/bash
STATUS=`mount | grep $(readlink -f /dev/disk/by-uuid/C6576A087368B015 )`
if [[ ! -z $STATUS ]]; then
    udisksctl unmount --block-device /dev/disk/by-uuid/C6576A087368B015
fi
exit 0

Conclusions

It is early days, but so far the login problem for other users after resuming from suspension has not reoccurred since I made the latest changes. I am not sure if the modifications described in my post ‘Prevent Lubuntu 17.10 from leaving an external HDD mounted incorrectly for other users‘ contributed to (or caused) the login problem, or whether one or more of systemd-logind, LightDM, LightDM GTK+ Greeter, Light Locker and Xfce Power Manager are to blame (since they have to work holistically to provide the required functionality). It is frustrating not knowing the root cause of the problem, but at least my family no longer has to worry about being able to log in if a family member has not logged out and left the PC to suspend.

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Getting the lock screen to work properly when resuming from Suspend-to-RAM with multiple sessions in Lubuntu 17.10

Introduction

What is it with Linux and lock screens?! There are umpteen posts on the Web by Linux users having trouble with lock screens, particularly the LightDM session locker Light Locker. Well, here is my contribution.

Lubuntu 17.10 is installed on my family’s desktop PC (single seat, multiple users). Lubuntu 17.10 uses systemd-logind, LightDM, Light Locker and Xfce Power Manager, and they do not work properly holistically in my experience. To confuse matters further, Lubuntu 17.10 also has XScreenSaver installed, which also has lock-screen capabilities.

In Lubuntu 17.10 on my family’s desktop PC, Light Locker displays the LightDM GTK+ Greeter screen when anyone wakes/resumes the PC from suspension by pressing a key on the USB keyboard, and users should then be able to log in by selecting their username from the pull-down list on the LightDM GTK+ Greeter screen and entering their password. However, if only a single user session existed when the PC suspended automatically (i.e. by timeout), upon resuming from suspension a black screen with a white padlock icon and the following message in white/grey text from light-locker would appear:

This session is locked
You’ll be redirected to the unlock
dialog automatically in a few seconds

But then nothing else happened; the above-mentioned message remained on display. I could press Ctrl+Alt+F1, login on TTY1 and enter the command ‘loginctl unlock-sessions‘ to get back to the Desktop, but that is not something the rest of my family would know how to do or be comfortable doing. In any case, I have only given sudo rights to one other member of the family.

Another problem would occur if the PC was left to suspend automatically with more than one user still logged in (i.e. more than one session). Although Light Locker would display the LightDM GTK+ Greeter screen upon resuming from suspension, and users could select their username from the pull-down list and enter their password, the LightDM GTK+ Greeter screen would remain on display and it would no longer be possible to re-enter a password (although it was still possible to select users from the pull-down list of users, and to select ‘Suspend’, ‘Restart…’ and ‘Shutdown…’ from the pull-down power menu). However, if users suspended the PC manually by selecting ‘Logout’ > ‘Lock Screen’ from the Lubuntu Menu, upon waking/resuming it was possible to enter their password on the LightDM GTK+ Greeter screen to return to their Desktop.

In this article I explain what I did to try and rectify these problems.

By the way, note that hibernation is disabled by default in Lubuntu 17.10 and you may need to make further changes if you want to enable hibernation as well. For example, does the PC have a swap partition, and is it large enough to enable hibernation? Also see the article: How to Enable Hibernate in Ubuntu 17.10 for possible help.

Modifications

The package light-locker-settings was not installed in Lubuntu 17.10. Do not install it. If it happens to be installed do not use ‘Preferences’ > ‘Light Locker Settings’, as it makes the Exec entry in the user’s light-locker.desktop file just ‘Exec=‘ or ‘Exec=light-locker‘. In fact, having installed light-locker-settings manually to check what could be configured via its GUI, I uninstalled it in order to stop anyone using it. (Under ‘Screensaver’, the Light Locker Settings GUI displays the following message: ‘Your screensaver settings are managed by Xfce Power Manager.’ and there is a button ‘Open’ to click on to launch the Xfce Power Manager settings GUI.) Presumably this was why it was not included when Lubuntu 17.10 was first installed to the HDD.

1.  I removed any light-locker.desktop files of individual users, leaving only the system-wide file:

$ sudo rm /home/*/.config/autostart/light-locker.desktop
$ sudo updatedb
$ locate light-locker.desktop
/etc/xdg/autostart/light-locker.desktop

2.  I edited the system-wide light-locker.desktop file to contain the following command to execute Light Locker:

$ grep Exec /etc/xdg/autostart/light-locker.desktop
Exec=light-locker --lock-after-screensaver=0 --no-lock-on-suspend --no-lock-on-lid --no-idle-hint

3.  I created the Bash script file /lib/systemd/system-sleep/hang-fix for systemd to run when suspending and resuming from suspension, with the permissions shown:

#!/bin/sh
case "$1" in
    pre|suspend|hibernate)
        date | tr -d '\n' >> /home/fitzcarraldo/sleep.log
        echo " going to sleep." >> /home/fitzcarraldo/sleep.log
        chvt 1
        loginctl unlock-sessions
    ;;
    post|resume|thaw)
        date | tr -d '\n' >> /home/fitzcarraldo/sleep.log
        echo " waking from sleep." >> /home/fitzcarraldo/sleep.log
        loginctl lock-sessions
        chvt 7
    ;;
    *)
        exit $NA
    ;;
esac
exit 0

$ sudo chmod 755 /lib/systemd/system-sleep/hang-fix
$ ls -la /lib/systemd/system-sleep/hang-fix
-rwxr-xr-x 1 root root 581 Apr 14 08:09 /lib/systemd/system-sleep/hang-fix

The above script is a hack to get around the problem of Light Locker resuming and apparently not knowing which session to unlock. I used the loginctl commands in this script rather than the Xfce Power Manager suspend options and Light Locker options such as ‘--late-locking‘ and ‘--lock-on-suspend‘ because I found that the Light Locker options and the Xfce Power Manager options did not fix the problem.

4.  I created two files for Polkit (to cover all Polkit versions to date) with the permissions as shown below.

4.1  The file /etc/polkit-1/rules.d/85-suspend.rules with the following contents:

polkit.addRule(function(action, subject) {
    if (action.id == "org.freedesktop.login1.suspend" ||
        action.id == "org.freedesktop.login1.suspend-multiple-sessions" ||
        action.id == "org.freedesktop.login1.hibernate" ||
        action.id == "org.freedesktop.login1.hibernate-multiple-sessions")
    {
        return polkit.Result.YES;
    }
});

If you do not have a swap partition large enough to enable hibernation, or you do not want to allow the PC to hibernate, use the following instead of the above:

polkit.addRule(function(action, subject) {
    if (action.id == "org.freedesktop.login1.suspend" ||
        action.id == "org.freedesktop.login1.suspend-multiple-sessions")
    {
        return polkit.Result.YES;
    }
});

$ sudo chmod 755 /etc/polkit-1/rules.d
$ sudo chmod 644 /etc/polkit-1/rules.d/85-suspend.rules
$ ls -la /etc/polkit-1/rules.d/85-suspend.rules
-rw-r--r-- 1 root root 359 Apr 19 22:14 /etc/polkit-1/rules.d/85-suspend.rules

4.2  The file /var/lib/polkit-1/localauthority/50-local.d/50-enable-suspend-on-lockscreen.pkla with the following contents:

[Allow suspending with lock screen]
Identity=unix-user:*
Action=org.freedesktop.login1.suspend;org.freedesktop.login1.suspend-multiple-sessions;org.freedesktop.login1.hibernate;org.freedesktop.login1.hibernate-multiple-sessions
ResultAny=yes
ResultInactive=yes
ResultActive=yes

If you do not have a swap partition large enough to enable hibernation, or you do not want to allow the PC to hibernate, use the following instead of the above:

[Allow suspending with lock screen]
Identity=unix-user:*
Action=org.freedesktop.login1.suspend;org.freedesktop.login1.suspend-multiple-sessions
ResultAny=yes
ResultInactive=yes
ResultActive=yes

$ sudo chmod 644 /var/lib/polkit-1/localauthority/50-local.d/50-enable-suspend-on-lockscreen.pkla
$ sudo ls -la /var/lib/polkit-1/localauthority/50-local.d/50-enable-suspend-on-lockscreen.pkla
-rw-r--r-- 1 root root 191 Apr 20 10:01 /var/lib/polkit-1/localauthority/50-local.d/50-enable-suspend-on-lockscreen.pkla

The above files are intended to get rid of the following error messages in a pop-up window and pop-up notification ballon, respectively, that prevent the OS from suspending automatically:

Authentication
Authentication is required for suspending
the system while other users are logged in.

Power Manager
GDBus.Error:org.freedesktop.DBus.Error.NoReply:
Method call timed out

By the way, the version of Polkit installed currently is 0.105:

$ pkaction --version
pkaction version 0.105

5.  I added all users to the users group (although I do not think this is essential):

$ sudo usermod -a -G users fitzcarraldo
$ sudo usermod -a -G users molly
$ sudo usermod -a -G users aquilino
$ sudo usermod -a -G users cholo
$ sudo usermod -a -G users paul

6.  I made sure the XScreenSaver settings for each user are as follows:

XScreenSaver (‘Preferences’ > ‘Screensaver’)

The ‘Display Modes’ tab has:

  • ‘Mode: Disable Screen Saver’

The ‘Advanced’ tab has everything unticked on it except for:

7.  I made sure the Xfce Power Manager settings for each user are as follows:

Xfce Power Manager (‘Preferences’ > ‘Power Manager’)

The ‘General’ tab has:
Buttons

  • When power button is pressed: Ask
  • When sleep button is pressed: Do nothing
  • When hibernate button is pressed: Do nothing

Appearance

  • Show notifications is ticked
  • Show system tray icon is ticked

The ‘System’ tab has:
System power saving

  • System sleep mode: Suspend
  • When inactive for 15 Minutes (You can make the number of minutes different for each user, if you want.)

The ‘Display’ tab has:
Display power management settings

  • ‘Handle display power management’ is ticked
  • Blank after: 5 Minutes
  • Put to sleep after: Never
  • Switch off after: Never

The ‘Security’ tab has:
Light Locker

  • Automatically lock the session: Never
  • Delay locking after screensaver for: ‘1 Seconds’ is greyed out
  • ‘Lock screen when system is going for sleep’ is not ticked

8.  I made sure the ‘Default Applications for LXSession’ settings for each user are as follows:

Select ‘Preferences’ > ‘Default Applications for LXSession’, click on ‘Autostart’ and untick ‘XScreenSaver’ if it is ticked. ‘Power Manager’ and ‘Screen Locker’ should already be ticked, so tick them if they are not. I left ‘PolicyKit Handler’ and ‘PolicyKit Authentication Agent’ unticked (Lubuntu 17.10 uses Polkit, the successor to PolicyKit).

9.  Although Lubuntu 17.10 does not use GNOME, I found that gsettings is installed. I did the following just in case, although I believe it is irrelevant in this particular case:

$ gsettings --version
2.54.1
$ gsettings set org.gnome.desktop.screensaver ubuntu-lock-on-suspend 'false'
$ gsettings get org.gnome.desktop.screensaver ubuntu-lock-on-suspend
false
$ gsettings set org.gnome.desktop.screensaver lock-enabled 'false'
$ gsettings get org.gnome.desktop.screensaver lock-enabled
false

Conclusion

After doing all the above, upon resuming from Suspend-to-RAM on most, but not all, occasions it is now possible to select any username on the LightDM GTK+ Greeter screen, enter that user’s password and successfully display the user’s Desktop. The LightDM GTK+ Greeter screen no longer hangs/freezes every time.

When more than one user is logged in (i.e. there is more than one session), the PC will suspend automatically if there is no user activity in a particular session during the configured timeout period for that session. Pressing a key on the USB keyboard will then wake the PC and display the LightDM GTK+ Greeter screen. The desired username can then be selected and the corresponding password entered. The following is an example of the sort of thing that can happen:

  • User fitzcarraldo (timeout configured as 30 minutes) logs in to his account at 09:00 and uses the PC until he locks his session manually (Ctrl+Alt+L) at 09:11.
  • User paul (timeout configured as 15 minutes) logs in to his account at 09:15 and uses the PC until he locks his session manually at 09:23.
  • User molly (timeout configured as 45 minutes) logs in to her account at 09:25 and uses the PC for several hours.
  • At 09:38, while user molly is using the PC, the PC automatically suspends to RAM (15 minutes after user paul stopped using his session). User molly has to wake the PC from suspension. Nothing is lost.
  • At 09:41, while user molly is using the PC, the PC automatically suspends to RAM (30 minutes after user fitzcarraldo stopped using his session). User molly has to wake the PC from suspension. Nothing is lost.

To avoid scenarios such as the above, if a user does not need the session any longer it is better to log out rather than leave the session in existence.

Syncing browser bookmarks between browsers and machines in Linux

I use several computers and various browsers (predominantly Firefox, Chrome and Chromium) and was fed up with bookmarking a site on one machine and later not finding it on another machine. For quite some time I had therefore been looking for a simple way of synchronising browser bookmarks across all my machines and browsers, and I finally found one. Below I explain what I did.

I wanted to avoid storing my bookmarks on a third-party company’s server, so that ruled out tools such as Xmarks, EverSync, Google Bookmarks and the like. I wanted the bookmark database to reside on one of my own servers that is already accessible securely via the Internet. Apparently Xmarks optionally does enable you to use your own server providing you use only Firefox, but I use various browsers (Firefox is the default browser on my main laptop whereas Chrome is the default browser on my backup laptop, for example). Furthermore, I prefer to use open-source solutions whenever possible.

Although I was looking for a GUI solution, it turns out that the command-line bookmark manager Buku does a good job in a drop-down terminal such as Yakuake, Guake or Tilda. Buku is quite powerful, yet simple to use. It is certainly practical to use in a drop-down terminal (I’m currently using it with Yakuake in KDE, and with Tilda in LXDE). Not only can you click on links to open pages in the default browser, you can also easily configure your desktop environment to use a keyboard shortcut to bookmark directly from the browser window (see the instructions in the Buku Wiki for details).

Of course, if you only want to use Buku as a local bookmark manager on a machine, you can just install it and use it solely on that machine.

It is not difficult to set up a centralised Buku database that is then synchronised with any machine on which Buku is installed. If you do not have your own Cloud server (ownCloud or Nextcloud, for example), you could use Dropbox instead. The instructions are given in the Buku Wiki. Basically, I did the following to configure several machines to use Buku via the Cloud:

1. Use each browser’s bookmark manager to export the bookmarks to a file.

2. Install Buku on each machine (see ‘Installation‘ on the package’s GitHub repository page if your Linux distribution’s package manager does not offer Buku).

3. Launch Buku once on each machine to create the local database:

$ buku -p
DB file is being created at /home/fitzcarraldo/.local/share/buku/bookmarks.db.
You should encrypt it.
[ERROR] 0 records

4. On one machine, move the Buku database file (~/.local/share/buku/bookmarks.db) to a folder on the machine that is already being synced with the Cloud, then set up a symlink to it. For example:

fitzcarraldo@clevow230ss ~ $ ls -la ~/.local/share/buku/bookmarks.db
lrwxrwxrwx 1 fitzcarraldo fitzcarraldo 51 Mar 21 13:17 /home/fitzcarraldo/.local/share/buku/bookmarks.db -> /media/NTFS/Windows/ownCloud/Bookmarks/bookmarks.db

5. Allow the Cloud client on the other machines to download the bookmarks.db file into their local Cloud sync folder, then delete the local Buku database on each machine (~/.local/share/buku/bookmarks.db) and create a symlink to the Cloud-synchronised database file. For example, in addition to the symlink shown above on the machine clevow230ss, I have the following symlinks on two other machines:

fitzcarraldo@aspirexc600:~$ ls -la ~/.local/share/buku/bookmarks.db
lrwxrwxrwx 1 fitzcarraldo fitzcarraldo 42 Mar 21 16:05 /home/fitzcarraldo/.local/share/buku/bookmarks.db -> /home/fitzcarraldo/ownCloud/Bookmarks/bookmarks.db
fitzcarraldo@meshedgedx ~ $ ls -la /home/fitzcarraldo/.local/share/buku/bookmarks.db
lrwxrwxrwx 1 fitzcarraldo users 42 Mar 26 19:15 /home/fitzcarraldo/.local/share/buku/bookmarks.db -> /home/fitzcarraldo/ownCloud/Bookmarks/bookmarks.db

6. Use Buku on each machine to import the browser bookmark files that you created in Step 1. See the Buku documentation for the command. You can find documentation and a demo video on the above-mentioned GitHub page. The commands ‘man buku‘ and ‘buku --help‘ also list the commands. The man(ual) page also contains several examples to help you.

7. Use Buku as normal on each machine. You will be able to search the synchronised database, add bookmarks and edit them (title, URL, comment and tags), delete bookmarks, print bookmarks, click on links to view the pages in the default browser, and so on.

Looking through a flat list of bookmarks in a terminal window to find something is not as fast as in a GUI but, overall, Buku is a decent bookmark manager and its options are easy to learn and use. Buku’s comprehensive search options of course help to find bookmarks, but it is still not quite as ergonomic as a GUI bookmark manager in my opinion. The ability to have multiple tags in Buku does help, as you can search for either any or all tags. In a browser’s bookmark manager I would copy the same bookmark into different folders if the Web page covers multiple topics.

In summary, Buku is a viable bookmark manager and I like it. It is extremely easy to configure for use with a Cloud server, and I have set it up to synchronise bookmarks on all my machines. I have already imported into Buku the 1,300+ bookmarks from the various browsers on my machines, and deleted the bookmarks in those browsers, so I am using Buku in earnest. I just kept a few of the most-used bookmarks on the browser’s Bookmarks Toolbar, but I’m using Buku on my machines for all the other bookmarks.

If I do have to use a third-party machine running Windows or Linux without Buku installed, I would not be able to access my bookmarks from my Cloud server. To partially get around that, I created a cron job for my user account on each of my machines to periodically run Buku and print the bookmarks to a text file synced on my Cloud server. That way I can at least search through the text file remotely via the Cloud’s Web browser interface (or via WebDAV or via OpenVPN) if I cannot find the Web page I want in a search engine on the third-party machine.

fitzcarraldo@clevow230ss ~ $ crontab -l | grep -v \#
6,26,46 * * * * rm /media/NTFS/Windows/ownCloud/Bookmarks/*.txt; sleep 30s && /usr/bin/buku -p --nc > /media/NTFS/Windows/ownCloud/Bookmarks/Buku_bookmarks_backup.txt
fitzcarraldo@aspirexc600:~$ crontab -l | grep -v \#
1,21,41 * * * * rm /home/fitzcarraldo/ownCloud/Bookmarks/*.txt; sleep 30s && /usr/local/bin/buku -p --nc > /home/fitzcarraldo/ownCloud/Bookmarks/Buku_bookmarks_backup.txt
fitzcarraldo@meshedgedx ~ $ crontab -l | grep -v \#
11,31,51 * * * * rm /home/fitzcarraldo/ownCloud/Bookmarks/*.txt; sleep 30s && /usr/bin/buku -p --nc > /home/fitzcarraldo/ownCloud/Bookmarks/Buku_bookmarks_backup.txt

Below is a small taste of searching the bookmark database using Buku on any of my machines. Output is colour-coded (user-configurable), and links are clickable in a terminal window. You can search for any keyword(s), all keywords, sub-strings, just a tag or tags, regular expression matches, and so on. You can make titles immutable (read-only) if you want, or allow Buku to update them with the title from the Web site page. There is even a command that will check and list broken links. I will leave you to study the Buku documentation.

fitzcarraldo@aspirexc600:~$ buku -S Brazil samba
1. Kaká e Mário Monteiro são os novos carnavalescos da Imperatriz Leopoldinense [159]
   > http://www.sidneyrezende.com/editoria/carnaval
   +  Notícias sobre Carnaval 2016, escolas de samba, desfiles do Grupo Especial, Série A, ensaios técnicos, enredos, carnavalescos, bateria, mestre-sala, porta-bandeira, samba. Mangueira, Unidos da Tijuca, Vila Isabel, Beija-Flor, Grande Rio, Imperatriz, Mocidade, Portela, Salgueiro, União da Ilha, Viradouro, São Clemente, Porto da Pedra, Império da Tijuca, Império Serrano, Estácio de Sá, Caprichosos de Pilares, Tradição, Cubango, Em Cima da Hora, Inocentes de Belford Roxo, Alegria da Zona Sul, Unidos de Padre Miguel, Unidos de Bangu, Renascer de Jacarepaguá, Acadêmicos da Rocinha, Acadêmicos de Santa Cruz, Paraíso de Tuiuti, União de Jacarepaguá, União do Parque Curicica.
        
   # brazil,carnaval

2. Samba do Tuiuti 2018  Versão Acústica - YouTube [1270]
   > https://www.youtube.com/watch?v=yUxfwAzHOeY
   # brazil,carnaval,music,samba,video

buku (? for help) q

In this post I have only scratched the surface of what Buku can do. For example, a simple Buku command will encrypt (AES256) the bookmark database so you can prevent others viewing your bookmarks after you have finished searching the database, should you decide to store the database on a third-party Cloud server such as Dropbox. The search and editing tools are comprehensive yet straightforward, and you will quickly learn how to use them. I take my hat off to its developer, Arun Prakash Jana from Bangalore, India. He and the other contributors to Buku have done a great job, and I recommend you give Buku a try.

Gentoo Linux: A work-around to be able to Resume from Suspend to RAM when using the NVIDIA closed-source driver

My Clevo W230SS laptop has NVIDIA Optimus graphics hardware (NVIDIA GPU plus Intel IGP). I do not use Bumblebee, preferring to switch between the Intel video driver and the NVIDIA closed-source driver myself (see Switching between Intel and NVIDIA graphics processors on a laptop with NVIDIA Optimus hardware running Gentoo Linux). The laptop can suspend to RAM and resume perfectly when using the Intel video driver (but see Stopping my laptop spontaneously resuming immediately after Suspend to RAM, which is applicable whatever the GPU or IGP).

In order to be able to resume properly from Suspend-to-RAM when using the NVIDIA driver, the laptop needs to disable compositing before suspending, then re-enable compositing after resuming. For how I achieve that, see under Problem 2 in the third link above. If this is not done, the graphics on the Desktop are corrupted after resuming.

However, recently when using the NVIDIA driver and KDE Plasma 5 (I am currently using nvidia-drivers-387.22 and plasma-meta-5.11.5), when resuming from suspension the monitor would briefly display the LightDM wallpaper (I use different wallpapers for the desktop manager and the lock screen, so I know it was not the KDE lock screen) followed by a blank screen with a mouse pointer (which I could move normally). More recently, in between displaying the desktop manager’s wallpaper and the blank screen, the monitor would briefly display an earlier image of the Desktop just before the laptop suspended.

Now, I could simply leave the laptop configured to use the Intel driver. However, sometimes I need to use a CAD application and the performance is better when using the NVIDIA GPU.

There are umpteen posts on the Web about this problem, and the root cause seems to be the closed-source NVIDIA driver. I have seen the KDE lock screen mentioned in some posts as the culprit, so I disabled the lock screen (‘System Settings’ > ‘Desktop Behaviour’ > ‘Screen Locking’) but that did not solve the problem.

I put up with this for several weeks in the hope that the next release of the NVIDIA driver would fix the problem. If I suspended to RAM while the laptop was using the NVIDIA driver, I was able to resume and get to a working Desktop – albeit without the open windows and applications that had been running before suspending – by pressing Ctrl+Alt+F1 to get to TTY1, logging in as the root user and entering the command ‘/etc/init.d/xdm restart‘. However, the final straw was in a meeting a couple of weeks ago when I wanted to resume the laptop and show a worksheet to someone. The laptop monitor of course displayed a blank screen with a mouse pointer, and it took me a couple of minutes to restart the desktop manager, login to KDE Plasma 5 and open the spreadsheet again. So this week I decided to look into the problem to see if I could at least find a work-around that would enable the laptop to resume without needing to restart X Windows and login to Plasma 5 each time.

I created a Bash script in /etc/pm/sleep.d/ to unload the NVIDIA modules before suspending to RAM and to re-load them when resuming, but that did not solve the problem either.

I switched the rendering background from OpenGL 2.0 to OpenGL 3.1 (‘System Settings’ > ‘Display and Monitor’ > ‘Compositor’), but that did not work either. I switched the rendering backend to XRender, and that did enable the laptop to resume from suspend successfully with the NVIDIA driver, but I do not want to use that work-around. Firstly, with software rendering there is a performance hit, and, secondly, there was no KDE Desktop Cube when using XRender instead of OpenGL. I use the Desktop Cube when working, as I often have a lot of windows open on each virtual desktop (cube side), and I find it easier to use the cube than a flat UI.

Eventually I found that, after resuming, if I pressed Ctrl+Alt+F1 to get to a virtual console, logged into my user account, entered the command ‘DISPLAY=:0 /usr/bin/kwin_x11 --resume‘ and then pressed Ctrl+Alt+F7 to get back to TTY7, my Desktop would appear on TTY7. Even so, I noticed on TTY1 that the following error messages were displayed when I ran that command:

kwin_core: OpenGL 2 compositing setup failed
kwin_core: Failed to initialize compositing, compositing disabled

Anyway, the Plasma 5 Desktop was displayed on TTY7, and with the windows that were open when I suspended the laptop, so restarting KWin would at least be a viable work-around until NVIDIA fix their video driver.

I incoporated the command in my script /etc/pm/sleep.d/02-toggle-compositing like so:

#!/bin/sh
#
# Turn off compositing on hibernate or suspend
# Turn on compositing on thaw or resume

username=fitzcarraldo
userhome=/home/$username
export XAUTHORITY="$userhome/.Xauthority"
export DISPLAY=":0"

case "$1" in
     suspend|hibernate)
          su $username -c "qdbus org.kde.KWin /Compositor suspend" &
     ;;
     resume|thaw)
          su $username -c "qdbus org.kde.KWin /Compositor resume" &
          su $username -c "/usr/bin/kwin_x11 --replace" &
     ;;
     *)
          exit $NA
     ;;
esac

It is an ugly hack, but at least now the laptop can resume properly from Suspend-to-RAM while the NVIDIA driver is being used.

Perhaps Linus Torvalds was correct. I will try to avoid NVIDIA hardware when I replace my current laptop.

xdotool comes to the rescue

In a previous post I explained how I implemented a method for adding my current location and the local time to my e-mail signature wherever I happen to be in the World, irrespective of the time on the laptop’s hardware clock and system clock. In that post I described how I created a keyboard shortcut using the Linux application AutoKey. Unfortunately AutoKey has not been updated for several years and no longer works properly in KDE Plasma 5 on my laptops. Therefore I decided to replace it with a KDE keyboard shortcut, and this is to explain how I did it.

First create a custom shortcut in KDE:

  1. ‘System Settings’ > ‘Shortcuts’ > ‘Custom Shortcuts’
  2. ‘Edit’ > ‘New’ > ‘Global Shortcut’ > ‘Command/URL’, and name the New Action ‘Insert current time’
  3. On the Comment pane for ‘Insert current time’, add the comment ‘Insert current time at specified location’ (without the quotes)
  4. On the Trigger pane, configure the shortcut to be Ctrl+Alt+Space
  5. On the Action pane, enter the Command/URL as ‘/home/fitzcarraldo/timezone_signature_GeoNames.sh‘ (without the quotes)
  6. Click ‘Apply’

Next modify the Bash script timezone_signature_GeoNames.sh so that it contains the following (obviously change the username and path to suit):

#!/bin/bash

place=$(kdialog --title "Current Location" --inputbox "Enter your location:")

placetime=$(perl /home/fitzcarraldo/now1.pl $place)

# xdotool does not output a space in a string, so we have to extract each field from the string
# and print each field individually, separated by a space character.

city=$(echo $placetime | awk -F "|" '{print $1}')
country=$(echo $placetime | awk -F "|" '{print $2}' | sed 's/[)(]//g')
region=$(echo $placetime | awk -F "|" '{print $4}')

datetime=$(/usr/bin/zdump $region | awk -F " " '{print $2" "$3" "$4" "$5" "$6" "$7}')
dayofweek=$(echo $datetime | awk -F " " '{print $1}')
month=$(echo $datetime | awk -F " " '{print $2}')
day=$(echo $datetime | awk -F " " '{print $3}')
time=$(echo $datetime | awk -F " " '{print $4}')
year=$(echo $datetime | awk -F " " '{print $5}')
timezone=$(echo $datetime | awk -F " " '{print $6}')

activewindow=$(xdotool getactivewindow)

xdotool type --window $activewindow "Sent from:"
for oneword in $city; do
    xdotool key --window $activewindow space
    sleep 0.1s
    xdotool type --window $activewindow --delay 100 $oneword
done
xdotool key --window $activewindow comma
for oneword in $country; do
    xdotool key --window $activewindow space
    sleep 0.1s
    xdotool type --window $activewindow --delay 100 $oneword
done
xdotool key --window $activewindow Return
xdotool type --window $activewindow "Local time now: "
xdotool type --window $activewindow $dayofweek
xdotool type --window $activewindow " "
xdotool type --window $activewindow $month
xdotool type --window $activewindow " "
xdotool type --window $activewindow $day
xdotool type --window $activewindow " "
xdotool type --window $activewindow $time
xdotool type --window $activewindow " "
xdotool type --window $activewindow $year
xdotool type --window $activewindow " "
if [ ${timezone:0:1} = "-" ]; then
    timezone="UTC-"${timezone#*-}
elif [ ${timezone:0:1} = "+" ]; then
    timezone="UTC+"${timezone#*+}
fi
xdotool type --window $activewindow $timezone
xdotool type --window $activewindow " "
xdotool key --window $activewindow Return
xdotool key --window $activewindow Return
echo

The Perl script now1.pl is listed in my my earlier post. Notice that the script timezone_signature_GeoNames.sh in my earlier post was much simpler. This was because the AutoKey shortcut took care of sending the text to the currently active window. Without AutoKey, I now had to do this myself in the script timezone_signature_GeoNames.sh, and the command xdotool came to the rescue. The developer explains what xdotool does as follows:

This tool lets you simulate keyboard input and mouse activity, move and resize windows, etc. It does this using X11’s XTEST extension and other Xlib functions.

Additionally, you can search for windows and move, resize, hide, and modify window properties like the title. If your window manager supports it, you can use xdotool to switch desktops, move windows between desktops, and change the number of desktops.

So I installed xdotool via the Gentoo package manager:

# emerge xdotool
# eix xdotool
[I] x11-misc/xdotool
     Available versions:  3.20150503.1-r1^t ~3.20160805.1^t {examples}
     Installed versions:  3.20150503.1-r1^t(22:51:30 02/04/17)(-examples)
     Homepage:            http://www.semicomplete.com/projects/xdotool/
     Description:         Simulate keyboard input and mouse activity, move and resize windows

Anyway, my Bash script using xdotool works a treat with Thunderbird (and KWrite, LibreOffice Writer, etc.). I used to experience a problem with certain characters, for example a colon was printed as a semi-colon (see the xdotool bug report xdotool writes the wrong case #121), but that no longer happens in my current KDE Plasma 5 installation:

Sent from: Galeão International Airport, Brazil
Local time now: Thu Jul 6 15:11:40 2017 UTC-03

What a useful tool xdotool is!

Using the ClamAV daemon to scan files placed in my Downloads directory in Gentoo Linux

In a previous post I explained how to automatically detect files placed in my Downloads directory in Linux and scan them for viruses. The method I described in that post used clamscan, the command-line anti-virus scanner of ClamAV. Now, in addition ClamAV has a daemon (a program that runs continuously in the background), clamdscan, that you can enable. So I decided to switch to using clamdscan, as its response to downloaded files is much faster because the process waiting for new files to appear in ~/Downloads/ does not have to load clamscan from disk each time a new file arrives. Anyway, if you want to monitor a download directory in Gentoo Linux (running OpenRC) by using the ClamAV daemon — which will also download virus signature database updates automatically — then the procedure to set this up is given below.

1. Install clamav if it is not installed already:

root # emerge clamav

2. Add the service to the default runlevel:

root # rc-update add clamd default

The daemon will be launched automatically next time the computer boots.

3. The first download of the virus database has to be done manually:

root # freshclam

4. Start the daemon now:

root # rc-service clamd start

5. Create the Bash script ~/monitorDownloadsGUI with the following contents:

#!/bin/bash

DIR=$HOME/Downloads

# Get rid of old log file, if any
rm $HOME/virus-scan.log 2> /dev/null

IFS=$(echo -en "\n\b")

# Optionally, you can use shopt to avoid creating two processes due to the pipe
shopt -s lastpipe
inotifywait --quiet --monitor --event close_write,moved_to --recursive --format '%w%f' $DIR | while read FILE
# Added '--recursive' so that a directory copied into $DIR also triggers clamscan/clamdscan, although downloads
# from the Web would just be files, not directories.
do
     # Have to check file length is nonzero otherwise commands may be repeated
     if [ -s $FILE ]; then
          # Replace 'date >' with 'date >>' if you want to keep log file entries for previous scans.
          date > $HOME/virus-scan.log
          clamdscan --move=$HOME/virus-quarantine $FILE >> $HOME/virus-scan.log
          kdialog --title "Virus scan of $FILE" --msgbox "$(cat $HOME/virus-scan.log)"
     fi
done

Make it executable:

user $ chmod +x ~/monitorDownloadsGUI

6. Create the directory ~/virus-quarantine/ to store infected files pending investigation/deletion:

user $ mkdir ~/virus-quarantine

7. Install kdialog if it is not already installed:

root # emerge kdialog

8. Use ‘System Settings’ > ‘Startup and Shutdown’ > ‘Autostart’ to add the script ~/monitorDownloadsGUI to the list of script files that are automatically started each time you log in to KDE.

9. Log out then back in again, and you should see that everything is running as expected:

user $ rc-status | grep clam
 clamd                                                             [  started  ]

user $ ps -ef | grep clam | grep -v grep
clamav    1920     1  0 01:48 ?        00:00:00 /usr/sbin/clamd
clamav    1929     1  0 01:48 ?        00:00:00 /usr/bin/freshclam -d

user $ ps -ef | grep GUI | grep -v grep
fitzcarraldo      9143  8971  0 13:56 ?        00:00:00 /bin/bash /home/fitzcarraldo/.config/autostart-scripts/monitorDownloadsGUI.sh

10. To test, surf to http://www.eicar.org/85-0-Download.html and download one of the EICAR test files into your ~/Downloads/ directory. You should see a pop-up KDialog window with a message similar to the following:

Virus scan of /home/fitzcarraldo/Downloads/eicarcom2.zip — KDialog

Mon 27 Feb 14:05:26 GMT 2017
/home/fitzcarraldo/Downloads/eicarcom2.zip: Eicar-Test-Signature FOUND
/home/fitzcarraldo/Downloads/eicarcom2.zip: moved to ‘/home/fitzcarraldo/virus-quarantine/eicarcom2.zip’

———– SCAN SUMMARY ———–
Infected files: 1
Time: 0.001 sec (0 m 0 s)

Note that the above-mentioned pop-up window may be preceded by one or more pop-up windows with an error message. I’m using the Chrome browser at the moment, but you may get a similar message if you are using another browser. Here is an example:

Virus scan of /home/fitzcarraldo/Downloads/.com.google.Chrome.Uh3oGm — KDialog ?

Mon 27 Feb 14:16:30 GMT 2017
/home/fitzcarraldo/Downloads/.com.google.Chrome.Uh3oGm: Access denied. ERROR

———– SCAN SUMMARY ———–
Infected files: 0
Total errors: 1
Time: 0.000 sec (0 m 0 s)

Read the error message and click ‘OK’, as this is not an actual problem; it is inotifywait detecting temporary files in the ~/Downloads/ directory during the download process. With larger files sometimes several such messages are displayed, presumably because the file being downloaded is being opened and closed more than once during the downloading process. This issue does not occur if you copy or move a file into ~/Downloads/ from another directory in your installation; try it and see for yourself. Then you only get the one pop-up window with the scan result for the file you put in ~/Downloads/.

Also have a look in ~/virus-quarantine/ and you will see the EICAR test file in that directory. You can delete it if you want (it is not infected with a real virus, so does no harm).

In future be sure to read the messages in the pop-up windows before clicking ‘OK’, as they will inform you that an infected file has been moved to the quarantine directory.

That’s all there is to it. Very simple, and quite handy if you want to check quickly that files you download don’t have a malware payload. Just make sure you download all files into ~/Downloads/ or they will not be checked automatically. Also, if you are given e.g. a USB pen drive with a file on it, you can copy the file to ~/Downloads/ if you want it to be scanned for malware.

How to capture a screenshot of the SDDM greeter screen

In my previous post I explained how to capture a screenshot of the LightDM greeter screen. The procedure is essentially the same for the SDDM greeter screen; only the Bash script differs slightly. The procedure is given below.

  1. If they are not already installed, install the packages x11-apps/xwd and media-gfx/imagemagick.

  2. Create the Bash script ~/sddm-greeter-capture.sh containing the following:
    TMPXAUTHORITY=$(ls /var/run/sddm/*)
    sleep 30
    DISPLAY=:0 XAUTHORITY=/var/run/sddm/$TMPXAUTHORITY xwd -root > /tmp/greeter.xwd
    convert /tmp/greeter.xwd /home/fitzcarraldo/greeter.png
    

    Make sure you make it executable:

    user $ chmod +x sddm-greeter-capture.sh

  3. Log out of the Desktop Environment so that the SDDM greeter screen is displayed.

  4. Press Ctrl+Alt+F2 to switch to VT2.

  5. Log in to you user account and enter the following command (do not wait for it to complete):

    user $ sudo /home/fitzcarraldo/sddm-greeter-capture.sh

  6. As soon as you have pressed Enter for the above command, press Ctrl+Alt+F7 to switch back to VT7.

  7. Wait for at least 30 seconds to be sure the Bash script has made a snapshot of the SDDM greeter screen, then log in.

  8. You should now find the file ~/greeter.png containing a snapshot of your SDDM greeter screen.

If you install media-libs/netpbm instead of (or as well as) media-gfx/imagemagick then you can use a different command to convert in the Bash script:

TMPXAUTHORITY=$(ls /var/run/sddm/*)
sleep 30
#DISPLAY=:0 XAUTHORITY=/var/run/sddm/$TMPXAUTHORITY xwd -root | xwdtopnm | pnmtopng > /home/fitzcarraldo/greeter.png

The resulting PNG image looks equally good to my eyes.

How to capture a screenshot of the LightDM greeter screen

  1. If they are not already installed, install the packages x11-apps/xwd and media-gfx/imagemagick.

  2. Create the Bash script ~/lightdm-greeter-capture.sh containing the following:
    #!/bin/bash
    sleep 30
    DISPLAY=:0 XAUTHORITY=/var/run/lightdm/root/$DISPLAY xwd -root > /tmp/greeter.xwd
    convert /tmp/greeter.xwd /home/fitzcarraldo/greeter.png
    

    Make sure you make it executable:

    user $ chmod +x lightdm-greeter-capture.sh

  3. Log out of the Desktop Environment so that the LightDM greeter screen is displayed.

  4. Press Ctrl+Alt+F2 to switch to VT2.

  5. Log in to you user account and enter the following command (do not wait for it to complete):

    user $ sudo /home/fitzcarraldo/lightdm-greeter-capture.sh

  6. As soon as you have pressed Enter for the above command, press Ctrl+Alt+F7 to switch back to VT7.

  7. Wait for at least 30 seconds to be sure the Bash script has made a snapshot of the LightDM greeter screen, then log in.

  8. You should now find the file ~/greeter.png containing a snapshot of your LightDM greeter screen.

If you install media-libs/netpbm instead of (or as well as) media-gfx/imagemagick then you can use a different command to convert in the Bash script:

#!/bin/bash
sleep 30
DISPLAY=:0 XAUTHORITY=/var/run/lightdm/root/$DISPLAY xwd -root | xwdtopnm | pnmtopng > /home/fitzcarraldo/greeter.png

The resulting PNG image looks equally good to my eyes.

A long overdue update to Google Earth for Linux

Google has finally released Version 7.1.7.2600 of Google Earth for Linux, fixing various crashes and the infamous empty Panoramio window. The last version of Google Earth for Linux that worked properly ‘out of the box’ in Gentoo Linux for me was 5.2.1.1588, and that was several years ago.

The current version of Google Earth in the Portage main tree is 7.1.4.1529. That version does not display Panoramio photos in Gentoo Linux (Stable Branch) on my Clevo W230SS laptop (NVIDIA Optimus), and Version 7.1.4.1529 crashes at launch more often than not. So I was keen to try the new version. Below are the steps I followed to install Version 7.1.7.2600 in the Portage local overlay on the laptop. If you don’t already have a local overlay, see the Gentoo Wiki article Overlay/Local overlay. Don’t forget to copy the files directory and its contents from /usr/portage/sci-geosciences/googleearth/ to /usr/local/portage/sci-geosciences/googleearth/ as well.

1. Download the file google-earth-stable_current_amd64.deb from the Google Earth Web site (Download the latest version of Google Earth for PC, Mac or Linux).

2. Edit the file /etc/portage/package.use/googleearth and add the line:

=sci-geosciences/googleearth-7.1.7.2600 -bundled-libs

3. Edit the file /etc/portage/package.unmask/googleearth and add the line:

=sci-geosciences/googleearth-7.1.7.2600

4. Edit the file /etc/portage/package.accept_keywords/googleearth and add the line:

=sci-geosciences/googleearth-7.1.7.2600 ~amd64

5. Copy the downloaded binary package to the distfiles directory and rename the package:

root # cp /home/fitzcarraldo/Downloads/google-earth-stable_current_amd64.deb /usr/portage/distfiles/GoogleEarthLinux-7.1.7.2600_amd64.deb

6. Create an ebuild for the new version and generate a manifest:

root # cd /usr/local/portage/sci-geosciences/googleearth/
root # cp /usr/portage/sci-geosciences/googleearth/googleearth-7.1.4.1529.ebuild googleearth-7.1.7.2600.ebuild
root # ebuild googleearth-7.1.7.2600.ebuild manifest

7. Install Google Earth 7.1.7.2600:

root # emerge =googleearth-7.1.7.2600

The package was installed without any trouble:

root # eix -I googleearth
[I] sci-geosciences/googleearth
     Available versions:  {M}(~)7.1.4.1529^m {M}(~)7.1.7.2600^m[1] {+bundled-libs}
     Installed versions:  7.1.7.2600^m[1](00:02:27 02/10/16)(-bundled-libs)
     Homepage:            https://earth.google.com/
     Description:         A 3D interface to the planet

[1] "local_overlay" /usr/local/portage

Google Earth for Linux 7.1.7.2600 launches quickly and without trouble on this laptop, and Panoramio photos are indeed now visible again (finally!). The only issue is one I also came across over a year ago after hacking an earlier version of Google Earth for Linux: If you click on a photo icon and the Panoramio window that opens displays several thumbnails, clicking on a thumbnail results in a white Panoramio window without any photo and thumbnails. Apparently this only happens in KDE. Anyway, the work-around is to right-click on the desired thumbnail and select ‘Open in New Window’.

Completing PDF forms and adding your signature without having to print the form

A recent post in the Gentoo Forums made me interested to find out what is actually achievable with fillable PDF forms in Gentoo Linux and Windows 10 without being required to purchase a software licence, be it for personal or professional use, in order to be able to complete PDF forms (including forms that have automatically-updating bar codes).

Designing PDF Forms

It is possible to create PDF forms with LibreOffice, although LibreOffice cannot create a form containing bar codes that get updated automatically with the information entered in fields on the form. In order to create PDF forms that contain automatically-updating bar codes it is necessary to purchase Adobe Acrobat DC or Adobe LiveCycle Designer, which are Windows-only applications. As forms usually have several fields, 2D bar code symbologies are used in order to be able to encode the amount of data in a practical way. See the Adobe demonstration video Capture electronic data from printed forms.

Using PDF Forms

However, the enquiry in the above-mentioned forum thread was not about designing PDF forms, it was about being able to complete existing PDF forms (including forms that have automatically-updating bar codes, and including being able to add a written signature to the form without printing it out):

Hi,

I need to sign pdfs, and sometimes fill out pdf forms which also need to be signed. At the moment I get them, print them, sign them and scan them back in to return to the sender. I’d like to simplify that.

I know that on Windows and Mac OS your adobe software can sign the pdf, but I don’t even know how that works exactly.

It would be really neat if there were an app which could handle all that.

Oh yeah, another thing. Some forms (all?) when you fill them out and print them have a bar of machine-readable gobbledygook on the page which lets the recipient of a printed pdf scan the data back in with 100% accuracy. That would be neat too.

Thanks.

Although I have sometimes added my signature to a PDF form before printing it out — more on that later — I had never come across PDF forms with automatically-updating bar codes, so my curiosity was piqued. I decided to investigate if free applications could be used to complete PDF forms (including those with automatically-updating bar codes) and add a written signature. My investigations were carried out in Linux and Windows 10, and my findings are given below. In summary, I discovered that I could do all these things in Linux as well as in Windows 10, although in Linux I had to resort to running a Windows application under WINE if a PDF form contained automatically-updating bar codes. I did not bother trying the GNOME document viewer Evince, as I could find no evidence on the Web of it having the capability of updating bar codes automatically, and I use KDE.

For my tests I used the following four PDF forms I found on the Web:

  1. acrobat8_barcodedforms.pdf, an October 2006 PDF article from Adobe containing three sample form fields and an associated automatically-updating bar code (PDF417 symbology).
  2. barcode_field.pdf, a February 2013 sample PDF form with three fields and three associated bar codes of different symbologies (PDF417, Data Matrix and QR Code).
  3. PdfFormExample.pdf, a June 2013 sample PDF form created using LibreOffice (and therefore not containing automatically-updating bar codes).
  4. sample_barcoded_demo.pdf, a December 2005 sample PDF form from Adobe with an automatically-updating bar code (PDF417 symbology).

1. Windows 10

1.1 Acrobat Reader DC

This is the ubiquitous ‘free’ closed-source application you can download from Adobe.

Below are screenshots of the four sample PDF forms opened in Acrobat Reader DC…

1.1.1 I could enter text in the three fields in acrobat8_barcodedforms.pdf, and the bar code was updated accordingly:

Acrobat Reader DC - acrobat8_barcodedforms.pdf

Acrobat Reader DC - acrobat8_barcodedforms.pdf

I used my smartphone’s Barcode Scanner app to read the bar code on the hard-copy form printed by Acrobat Reader DC:

Text1Text2Text3I am able to change the text in these fields of this form to see how 2D barcodes work.

1.1.2 I could enter text in the three fields in barcode_field.pdf, but the three bar codes were not visible:

Acrobat Reader DC - acrobat8_barcodedforms.pdf

Acrobat Reader DC - barcode_field.pdf

1.1.3 I could enter text in the fields in PdfFormExample.pdf:

Acrobat Reader DC - PdfFormExample.pdf

Acrobat Reader DC - PdfFormExample.pdf

1.1.4 I could enter text in all fields of sample_barcoded_demo.pdf and the field contents were echoed in the box ‘Barcode Contents’ but the bar code itself was not visible:

Acrobat Reader DC - sample_barcoded_demo.pdf

Acrobat Reader DC - sample_barcoded_demo.pdf

So, in summary, Acrobat Reader DC is not a viable option if you have to deal with forms that include automatically-updating bar codes.

1.2 PDF-XChange Editor

This application from Canadian company Tracker Software Products supersedes their deprecated PDF-XChange Viewer and has additional features. Neither application is open-source, though. Some features only work fully if you purchase a software licence and enter the licence key. For example, if you add a signature to a PDF form (‘Document’ > ‘Signatures and Initials’) and then save it, DEMO stamps are added to the new PDF file (which still has editable fields). However, if you print the PDF form (either to a PDF file or to paper) then DEMO stamps are not added (but the new PDF file is not fillable/editable). Click on the two links below to view the sample PDF file PdfFormExample.pdf signed and saved to a new PDF file, and the sample PDF file PdfFormExample.pdf signed and printed to a new PDF file:

PdfFormExample_with_signature_added_then_Saved.pdf

PdfFormExample_with_signature_added_then_Printed_to_PDF.pdf

If you save them to disk and open them in PDF-XChange Editor, you will see the distinction.

As stated on the company’s Web site, the free application can be used for private and work purposes:

The FREE download of the PDF-XChange Editor may be used without limitation for Private, Commercial, Government and all uses, provided it is not: incorporated or distributed for profit/commercial gain with other software or media distribution of any type – without first gaining permission.

Below are screenshots of the four sample PDF forms opened in PDF-XChange Editor…

1.2.1 I could enter text in the three fields in acrobat8_barcodedforms.pdf, and the bar code was updated accordingly:

PDF-XChange Editor - acrobat8_barcodedforms.pdf

PDF-XChange Editor - acrobat8_barcodedforms.pdf

I used my smartphone’s Barcode Scanner app to read the bar code on the hard-copy form printed by PDF-XChange Editor:

Text1Text2Text3
I am able to change the text in these fields of this formto see how 2D barcodes work.

Notice that the layout of the encoded text is slightly different to the bar code generated by Adobe Acrobat Reader DC.

1.2.2 I could enter text in the three fields in barcode_field.pdf, and the three bar codes were visible:

PDF-XChange Editor - barcode_field.pdf

PDF-XChange Editor - barcode_field.pdf

I used my smartphone’s Barcode Scanner app to read the three bar codes on the hard-copy form printed by PDF-XChange Editor:

The PDF417 bar code was read as follows:

text_0:PDF417 barcode:I can enter text in these fields of this form and can see the three barcodes to the right of these fields in PDF-XChange Editor.

The Data Matrix bar code was read as follows:

text_1:Data Matrix barcode:
To change the barcode field to the right, type in this box. The barcode field to the right will reflect the contents of the text field as barcode after the text field lost the focus. To reset the contents of all barcode fields, cick the ‘Rset’ button.

Notice that the words ‘click’ and ‘Reset’ in the field were apparently not encoded correctly.

The QR Code bar code was read as a meaningless apparently random bunch of characters.

The PDF file and the three bar codes were generated on the fly by PHP code calling the pdflib library produced by the company PDFlib GmbH. I do not know how accurate this particular PDF file is, or how accurate is the Bar Code Scanner app on my smartphone.

1.2.3 I could enter text in the fields in PdfFormExample.pdf:

PDF-XChange Editor - PdfFormExample.pdf

PDF-XChange Editor - PdfFormExample.pdf

1.2.4 I could enter text in all fields of sample_barcoded_demo.pdf, and the field contents were echoed in the box ‘Barcode Contents’ and the bar code itself was visible:

PDF-XChange Editor - sample_barcoded_demo.pdf

PDF-XChange Editor - sample_barcoded_demo.pdf

I used my smartphone’s Barcode Scanner app to read the PDF417 bar code on the hard-copy form printed by PDF-XChange Editor:

Brian
S
Fitzgerald
Calle Fitzcarrald, 225
Iquitos

bsf@iquitos.nom.pe

So, in summary, PDF-XChange Editor appears to be a possible option in Windows 10, whether or not you have to deal with forms that include automatically-updating bar codes. I am quite impressed with the application.

2. Linux

2.1 Acrobat Reader 9

This is the free closed-source Linux application you can install via the Portage package manager (the package is app-text/acroread).

Below are screenshots of the four sample PDF forms opened in Acrobat Reader 9 for Linux.

2.1.1 I could enter text in the three fields in acrobat8_barcodedforms.pdf, and the bar code was updated accordingly:

Acrobat Reader 9 Linux - acrobat8_barcodedforms.pdf

Acrobat Reader 9 Linux - acrobat8_barcodedforms.pdf

I used my smartphone’s Barcode Scanner app to read the bar code on the hard-copy form printed by Acrobat Reader 9 for Linux:

Text1Text2Text3I am able to change the text in these fields of this form to see how 2D barcodes work.

2.1.2 I could enter text in the three fields in barcode_field.pdf, but the three bar codes were not visible:

Acrobat Reader 9 Linux - barcode_field.pdf

Acrobat Reader 9 Linux - barcode_field.pdf

2.1.3 I could enter text in the fields in PdfFormExample.pdf:

Acrobat Reader 9 Linux - PdfFormExample.pdf

Acrobat Reader 9 Linux - PdfFormExample.pdf

2.1.4 I could enter text in all fields of sample_barcoded_demo.pdf, and the field contents were echoed in the box ‘Barcode Contents’ but the bar code itself was not visible:

Acrobat Reader 9 Linux - sample_barcoded_demo.pdf

Acrobat Reader 9 Linux - sample_barcoded_demo.pdf

So, in summary, Acrobat Reader 9 for Linux is not a viable option if you have to deal with forms that include automatically-updating bar codes.

2.2 Okular

This is the well-known KDE document viewer application.

Below are screenshots of the four sample PDF forms opened in Okular.

2.2.1 I could enter text in the three fields in acrobat8_barcodedforms.pdf but the bar code was not visible:

Okular - acrobat8_barcodedforms.pdf

Okular - acrobat8_barcodedforms.pdf

2.2.2 I could enter text in the three fields in barcode_field.pdf but the three bar codes were not visible:

Okular - barcode_field.pdf

Okular - barcode_field.pdf

2.2.3 I could enter text in the fields in PdfFormExample.pdf:

Okular - PdfFormExample.pdf

Okular - PdfFormExample.pdf

2.2.4 I could enter text in all fields of sample_barcoded_demo.pdf but the field contents were not echoed in the box ‘Barcode Contents’ and the bar code itself was not visible:

Okular - sample_barcoded_demo.pdf

Okular - sample_barcoded_demo.pdf

So, in summary, Okular is not a viable option if you have to deal with forms that include automatically-updating bar codes. In fact, Okular was the worst of the bunch.

2.3 PDF-XChange Editor

To install this Windows application under WINE in Linux:

$ export WINEPREFIX=$HOME/.wine-pdfxve6
$ export WINEARCH="win32"
$ winecfg # Select Windows 10.
$ cd .wine-pdfxve6/drive_c/
$ # Copy downloaded installer to C: drive:
$ cp ~/Downloads/PDFXVE6.zip .
$ unzip PDFXVE6.zip
$ # Install PDF-XChange Editor:
$ wine PDFXVE6.exe

  • Click ‘Install’.
  • Click ‘Next’.
  • Select ‘I accept the terms in the License Agreement’ and click ‘Next’.
  • Click ‘Custom’.
  • Click ‘Browsers Plugins’ and select ‘Don’t install’. Click ‘Next’.
  • Leave ‘Create a Start Menu folder’ ticked. Untick ‘Create Desktop Icons.’ Untick ‘Set PDF-XChange Editor as default application for PDF files’. Untick ‘Set Printer “PDF-XChange Lite V6” As Default’. Click ‘Next’.
  • Select ‘Free Version’ and click ‘Next’.
  • Click ‘Install’.
  • Untick ‘Launch PDF-XChange Editor’ and click ‘Finish’.
  • Click ‘Close’.

KDE Plasma 5 then has an entry for PDF-XChange Editor in the Application Launcher under ‘Applications’ > ‘Wine’ > ‘Programs’ > ‘Tracker Software’. Alternatively, to launch PDF-XChange Editor from the command line, you should enter:

$ WINEPREFIX="$HOME/.wine-pdfxve6" && WINEARCH="win32" && wine $WINEPREFIX/drive_c/Program\ Files/Tracker\ Software/PDF\ Editor/PDFXEdit.exe

If you also want the Windows application running under WINE to be able to access PDF files on a NAS, i.e. to be able to open Samba shares, see my previous post How to enable a Windows application in WINE to access a Samba share on a NAS.

I will not bother showing screenshots of the four sample PDF files open in PDF-XChange Editor running under WINE in Linux, as the application’s behaviour is the same as in Windows (see the screenshots in sections 1.2.1 to 1.2.4 above). So, in summary, PDF-XChange Editor appears to be a viable option in Linux (albeit running under WINE), irrespective of whether or not you have to deal with forms that include automatically-updating bar codes.

3. Adding a signature to a soft copy of the PDF form

I am referring to a person’s written signature here, not to a digital signature. Rather than having to print the completed form on paper in order to sign it with a pen, then scan the fully-completed form in order to send it via e-mail, fax or whatever, many people wish to add their signature directly to the PDF form without having to print it. Below I explain the method I use to do this in both Linux and Windows.

3.1 Create a PNG file with your signature (one-time operation)

  1. Get a blank white piece of paper.
  2. Sign your name on the page.
  3. Scan the page with your scanner and save the image as a PNG file.
  4. Open the image with GIMP.
  5. Crop the image around the signature.
  6. Select ‘Layer’ > ‘Transparency’ > ‘Add Alpha Channel’.
  7. Select the Fuzzy Select Tool from the toolbox.
  8. Click on each white area and press the Delete key. Do this for the area around the signature and inside any loops. Obviously don’t click on the signature itself.
  9. Select ‘File’ > ‘Export’.
  10. Save the image as a PNG file.

3.2 Signing PDF documents

  1. Launch LibreOffice Draw and open the PDF file you wish to sign.
  2. Select ‘Insert’ > ‘Image…’ and select the PNG file of your signature. The image will be inserted.
  3. To move the signature around on the page, hover the mouse cursor over the image until the cursor changes to a red dot with four arrowheads, then click-and-hold to grab the image drag it.
  4. To reduce the size of the signature, hover the mouse cursor over the image until the cursor changes to a red dot with four arrowheads, then click and release. You will then see small blue ‘handles’ on the outline of the image. Hover the mouse cursor over a handle at one of the four corners of the image until the cursor changes to a Resize cursor. Click-and-hold and move the cursor to increase or decrease the size of the signature whilst maintaining the ratio of width to height.
  5. To save the completed and signed PDF form, select ‘File’ > ‘Export as PDF…’, click on ‘Export’ and give the file a name of your choice.

The new PDF file will contain all the information visible on the previous PDF file plus your written signature. However, unlike the original PDF file, you will not be able to modify any of the data. Therefore I recommend you retain a copy of the original PDF file before you added the signature, in case you wish to change any of field entries in future.

Note that the free PDF-XChange Editor can be used instead of LibreOffice Draw providing the PDF form is not secured or restricted, and providing you print it to a new PDF file using a virtual PDF printer driver. If the PDF form is secured or changes restricted, then use LibreOffice Draw as described above.

If you are using a PDF viewer that refuses to save your completed form as a PDF file after you have entered data in the fields (notice the message in the purple bar in the screenshots of Acrobat Reader 9 for Linux, for example), print the page to a PDF file instead by using the virtual PDF printer (‘Microsoft Print to PDF’ in Windows; CUPS ‘Virtual PDF Printer’ in Linux) at a resolution of e.g. 600 dpi (if possible). You should then be able to open that PDF file in LibreOffice Draw or PDF-XChange Editor to add your signature as explained above and print the signed form to a new PDF file.