simon.schönbeck.dk

Tag: linux

  • KDE Plasma sunrise (bright) & sunset (dark) theme automatic switch

    Under System Settings > Appearance & Style > Colours & Themes > Night Light in KDE Plasma there is the expected option to automatically switch at specific times between cool and warm colour temperature for the screen. I marked my location on the map and selected Sunset and sunrise at manual location to take care of the switch automatically. This works perfectly!

    For whichever reason, and there is many, KDE Plasma cannot do the same with the bright and dark theme. This is such a miss that one wonders how anything ever gets agreed upon in large open source projects such as KDE in this case. Gnome supports the option as many other.

    As there are more ways than one to skin a cat, I had several choices to work around this missing feature. I was really looking for something quick and dirty, nothing to install and trust, and easy to undo if needed.

    I decided to use the colour temperature as an indicator of when the bright or dark theme was needed. So at 6500 K it was the cool day light temperature and the bright theme should be used. On the contrary anything below this temperature, that is warm night light, should use the dark theme. Then I would simply check for this system value at a set interval and change the theme if it changed. This simple script is placed in the System Settings > System > Autostart section as an Application and it will launch upon boot and run in the background. Copy or download & unzip the below file and remember to make the .sh file executable:

    #!/bin/bash

    current_theme=""

    while true; do
      # Retrieve the current temperature from KWin using dbus-send
      temperature=$(dbus-send --session --dest=org.kde.KWin --type=method_call --print-reply \
        /org/kde/KWin/NightLight org.freedesktop.DBus.Properties.Get string:org.kde.KWin.NightLight string:currentTemperature \
        | grep -oP 'variant\s+uint32\s+\K\d+')

      # Decide the target theme based on the temperature
      if (( temperature == 6500 )); then
        target_theme="org.fedoraproject.fedora.desktop"  # Light theme for == 6500
      elif (( temperature < 6500 )); then
        target_theme="org.kde.breezedark.desktop"  # Dark theme for < 6500
      fi

      # Switch theme only if it's different from the current one
      if [[ "$target_theme" != "$current_theme" ]]; then
        lookandfeeltool -a "$target_theme"
        # Update the current theme to the new one
        current_theme="$target_theme"
        # KDE notification
        notify-send "Theme Switcher" "Switched to $(basename "$target_theme") theme."
      fi

      # Sleep for 15 minutes (900 seconds)
      sleep 900
    done
    Download shell script

  • Empty Trash from the terminal

    For some reason I can not recall I went into my Trash bin on Fedora. There was unsurprisingly a lot of trash!

    I decided to empty the Trash bin but it only succeeded partially. I had a DVD directory that did not want to be deleted. Looking closer at the message it was a permissions error. Not sure how though, since if I did not have permissions to delete the directory from the Trash bin, how on Earth could I have moved it into the Trash bin to start with…!

    Looking around my home directory in the terminal I could not locate the exact spot to manually remove the directory. As always Google came to assistance and brought up a nice forum topic about how to empty the Trash bin in Fedora from the terminal.

    The simplest way would be to run the following command as root:

    rm -rf  ~/.local/share/Trash/files/*

  • Console recursive FTP client

    Sometimes data needs moving from server to server without FXP support. For this task there is nothing simpler than good old FTP.

    What about if you have a large number of subdirectories? As the plain FTP client can not fetch the files recursively shell scripting is usually the solution. But in cases where you do not really know neither the depth of the recursion or the naming convention of the file system structure, an alternative method is needed.

    This method is named NcFTP Client. I got to know about it today as I quickly needed to copy several gigabytes of data spread over several subdirectories and NcFTP did its job flawlessly. I did not even have to install it as Fedora 10 already came with it by default.

  • Pidgin certificate prompt

    Today using the version of Pidgin that came with Fedora 10 I received the following certificate prompt:

    Accept certificate for ows.messenger.msn.com?
    The root certificate this one claims to be issued by is unknown to Pidgin.

    The majority of cases of unknown certificate issuers are due to the chain of trust breaking down. This break down in the certificate chain is mainly caused by the software in question not including the intermediate certificate authorities certificates. Without these intermediate certificates the software can not verify through the certificate hierarchy up till the root certificate and therefore prompts the user about what to do.

    The options I received in the Pidgin prompt were:

    View certificate
    Accept
    Reject

    Upon selecting “View certificate” I am presented with the following details:

    Common name: ows.messenger.msn.com
    Fingerprint (SHA1): a9:9c:2d:ee:4a:d1:c8:7d:a7:c5:c3:05:32:98:5f:ee:57:87:73:8a
    Activation date: Tue Jan 29 14:37:21 2008
    Expiration date: Wed Jan 28 14:37:21 2009

    So far everything looks as it is a bona fide certificate but to verify the identity completely I load the page https://ows.messenger.msn.com/ in Firefox. As expected no certificate warnings were received and I opened the certificate viewer to see its details and confirmed the data matches up with the data received in Pidgin:

    certificate
    Certificate Viewer

    I can safely trust this certificate as Firefox has verified through the certificate chain that all intermediate certificates are valid too:

    certificate_chain
    Certificate Chain

    This certificate is simply used by Microsoft for the Live Messenger offline messaging service. Although you normally would trust verified certificates it did happen in the past that certificates were incorrectly issued to the wrong people. So always be cautious!

  • Virtualmin & suEXEC

    If by chance you have installed the Webmin module Virtualmin at some point you may have come across the following error message when setting up the module:

    Failed to save enabled features: The Suexec command on your system is configured to only run scripts under /var/www, but the Virtualmin base directory is /home. CGI and PHP scripts run as domain owners will not be executed.

    This error message is caused by using a version of suEXEC compiled by default to use /var/www as the document root of Apache. The suEXEC feature allows to execute scripts as the user owning the virtual host instead of the global apache user increasing security. The solution has either been to recompile suEXEC with the new desired path (/home in this case) or simply disable (Server Templates > Apache Website > Automatically add appropriate SuExec directive?) suEXEC completely inside the Virtualmin module configuration.

    A much simpler approach I used was to create a link between the two directories. I used mount to bind the two directories together and act as one. Voila, Virtualmin now continued the module setup without a remark!

    To achieve this I ran the following command as root:

    mount --bind /var/www /home

    That is it really. Now the directories act as one for the suEXEC wrapper too.

    Please note this will usually only last till next reboot. To mount permanently include the following line into your /etc/fstab:

    /var/www /home none bind

    The following is the extract from the mount man page:

    Since Linux 2.4.0 it is possible to remount part of the file hierarchy somewhere else. The call is
    mount --bind olddir newdir
    or fstab entry is:
    /olddir  /newdir  none  bind
    After this call the same contents is accessible in two places.  One can also remount a single file (on a single file).

    One note is that if you already had local users set up inside the /home directory you will mount on top of it, making the existing users data unavailable (not deleted). Simply unmount again and the users data will be back again. To get around this change the default path Virtualmin uses to create new virtual hosts home directories to something else e.g. /virtualmin. This can be done in the Users & Groups module.