Half a Page of Scribbled Linux

To see SSH hosts, including their local host names and IP addresses:

avahi-browse -tr _udisks-ssh._tcp

Source: https://www.drdobbs.com/parallel/network-discovery-tools-putting-dns-serv/231602470

Keywords:

After upgrading my laptop to Ubuntu 18 (or was it 16?), after a suspend/resume, the lock screen would appear promptly, but there was a delay of about a minute after hitting Enter before the login prompt appeared. This delay was due to CIFS mounts being restored. In prior versions of Ubuntu, the mounts would sometimes be restored and sometimes not, but it didn’t wait for that before the login screen. With Ubuntu 18, it waits for the mounts before the login screen appears.  While it’s nice to be sure the mounts are always restored, the delay is a sub-optimal user experience.  The solution is to use autofs, which only mounts file systems when they are accessed.  Here’s how that is done on my Thinkpad T560 with CIFS (Samba) mounts to a Synology DS411+II.

Install autofs and cifs-utils.

After installing autofs, unmount the mounts in /etc/fstab that you want to have managed by autofs.  Then edit /etc/fstab and comment them out.  Edit /etc/auto.master and add an entry for each directory that will contain mounts.  For example, to add mounts in /mnt:

/mnt /etc/auto.mnt

Keep in mind the contents of the directory being managed by autofs (/mnt in this example) will not be accessible once autofs makes mounts there.  The directory contents will not be deleted, you just won’t see them again until the mount is removed.

Create the mount configuration for each mounted directory.  In our example above that would be /etc/auto.mnt:

ds411p2-public-music -fstype=cifs,vers=1.0,rw,suid,gid=ds411p2,credentials=/etc/ds411p2pwd ://ds411p2.local/music

The format of this file is similar to /etc/fstab but not the same.  For comparison, here’s that entry as it was in /etc/fstab:

//ds411p2.local/music /mnt/ds411p2-public-music cifs vers=1.0,rw,suid,gid=ds411p2,credentials=/etc/ds411p2pwd 0 0

So to create the entry in /etc/auto.mnt from /etc/fstab:

• The first field, the mountpoint, is the second field from /etc/fstab, but change it from an absolute path to one relative to the mount directory specified in /etc/auto.master.
• The second field is a combination of fstab’s third and fourth fields, the file system type and mount options, except file system type is prefixed with -fstype=. The other mount options follow, separated by commas, the same as in fstab.
• The third field, the server directory, is the same as first field in fstab except it’s prefixed with :.
• The last two fields from fstab (dump and fsck options) aren’t used.

The default clock shown in the Gnome Panel has only the time in HH:MM format. If you want to display seconds or include the date, you need an extension called Clock Override. Instructions for installing it are here: http://ubuntuhandbook.org/index.php/2019/02/customize-time-date-format-ubuntu-18-04-gnome-panel/

Note, if searching for the extension in Ubuntu Software turns up nothing, go to the “All” tab, select the Add-ons category, click Extension Settings and turn on Shell Extensions. Clock Override will appear in a list of extensions below.

Get Sounds

Video game sounds are available at https://downloads.khinsider.com/game-soundtracks.

Select sounds for

• phone ringtone
• default alarm
• default notification
• Charging

Download sounds to the NAS. Rename them to prefix the game name and purpose. This is because the phone stores all ringtones in the same directory and names such as 01-Credit-Sound.mp3 are common and it’s easy to forget which sound you picked for something. For example, 01-Credit-Sound.mp3 becomes galaga-default-notification-01-Credit-Sound.mp3.

Copy sounds to phone

Copy the files to pCloud and download them on the phone. They’ll be stored in /storage/emulated/0/Download.

Using Ghost Commander, move them from the Download directory to the following locations:

• Phone Ringtone: /storage/emulated/0/Ringtones
• Default Alarm: /storage/emulated/0/Alarms
• Default Notification: /storage/emulated/0/Notifications
• Charging: /storage/emulated/0/Notifications

Select sounds on phone

Set the default ringtone, notification and alarm in Settings > Sound > Advanced.

Set the charging sound in Tasker.

Darktable exports photo fields to metadata as follows (as reported by exiv2 pr -pa {file}.jpg):

Darktable title -> Xmp.dc.title
Darktable description -> Xmp.dc.description
Darktable tagging section -> Xmp.dc:subject (as a comma-separated list)

Unfortunately, Piwigo does not read XMP metadata so only the description is available as Exif.Image.ImageDescription. IPTC is required for the title and tags. Darktable does not export IPTC, but can be scripted to copy XMP tags to IPTC. See instructions here: https://discuss.pixls.us/t/name-description-and-keywords-are-not-recognized-by-shutterstock/6726/26

and source code here: https://github.com/chrik5/lua-scripts/blob/exiftool/contrib/exiftool_export.lua

In Darktable, using exiftool on export from above, check enable exiftool, set options to -@ and create file xmp2iptc.txt with the following contents:

-XMP-dc:Subject > IPTC:Keywords
-XMP-dc:Description > IPTC:Caption-Abstract
# -XMP-dc:Title > IPTC:ObjectName

(uncomment out the last line if you want to use the Title in Darktable rather than the filename Piwigo uses by default; and update use_iptc_mapping array below)
Set this file as Argumentsfile.
Then export the files from Darktable.

Using Piwigo plugin LocalFiles Editor add these lines to local config file local/config/config.inc.php:

// use_iptc: Use IPTC data during database synchronization with files
// metadata
$conf['use_iptc'] = true;

// use_iptc_mapping : in which IPTC fields will Piwigo find image 
// information? This setting is used during metadata synchronisation. It 
// associates a piwigo_images column name to a IPTC key 
// See https://exiftool.org/TagNames/IPTC.html 
// and http://piwigo.org/doc/doku.php?id=user_documentation:metadata&s 
$conf['use_iptc_mapping'] = array(   
  'keywords'        => '2#025',
  'comment'         => '2#120'   
  );  

From this point on, you’ll only have to remember to activate exiftool on export in Darktable and Piwigo will do the rest.

On two new Ubuntu 18.04 installations, internet access was extremely slow on the first access of a website. I eventually tracked it down to IPv6 DNS, for instance:
dig slashdot.org A
would respond immediately, but
dig slashdot.org AAAA
would hang for a while then return
;; connection timed out; no servers could be reached
I checked the name servers returned by my ISP that my router was using and they worked fine. It was only when using the default DNS returned by my router’s DHCP that it hung. The reason for this was that IPv6 was disabled at the router, a NetGear R6700v2. To fix, log in to the router’s administration web page and go to Advanced -> Advanced Setup -> IPv6 and change Internet Connection Type from Disabled to DHCP.

Install synaptic:
sudo apt install synaptic

install pCloud from pcloud.com
Add synced directory pCloudDrive/sync -> ~/pcloud-sync

Download the KeePassX 0.4 .DEB from https://launchpad.net/ubuntu/xenial/amd64/keepassx/0.4.3+dfsg-0.1ubuntu1
sudo dpkg -i keepassx_0.4.3+dfsg-0.1ubuntu1_amd64.deb
sudo apt --fix-broken install
To prevent it from being upgraded to version 2, in Synaptic, select keepassx and, from the menu, select “Package” -> “Lock Version”. Also make sure Software Updater isn’t set to automatically install updates, as it does not respect the version lock.

Sign in to Firefox. If the menu is missing, hit F10 and select View -> Toolbars -> Menu Bar and Bookmarks Toolbar.

Use Synaptic to load these packages:
vim-gnome
gkrellm
kvpm (replaces system-config-lvm, which is not available for Ubuntu 18)
cifs-utils
gnucash
gimp
darktable
gnome-raw-thumbnailer (to view .CR2 file thumbnails, also view in Files with zoom of 150%)
git

Copy the /etc/group entry for ds411p2 from another machine that already has it.

Add an entry for the NAS to /etc/hosts, of the form:
192.168.123.123 ds411p2

Install NAS credentials
From another NAS-connected machine, copy the NAS authorization file:
/etc/ds411p2pwd. Set permissions to u=rw,go=. Repeat for ~/.ds411p2pwd.

Set up NAS mounts
As root, edit /etc/fstab and add these lines, substituting your username for {me}:

//ds411p2/video /mnt/ds411p2-public-video cifs vers=1.0,rw,suid,gid=ds411p2,credentials=/etc/ds411p2pwd 0 0
//ds411p2/music /mnt/ds411p2-public-music cifs vers=1.0,rw,suid,gid=ds411p2,credentials=/etc/ds411p2pwd 0 0
//ds411p2/photo /mnt/ds411p2-public-photo cifs vers=1.0,rw,suid,gid=ds411p2,credentials=/etc/ds411p2pwd 0 0

//ds411p2/home /home/{me}/ds411p2 cifs vers=1.0,user,uid={me},gid={me},rw,suid,credentials=/home/{me}/.ds411p2pwd 0 0
//ds411p2/video /home/{me}/ds411p2-public-video cifs vers=1.0,user,uid={me},gid={me},rw,suid,credentials=/home/{me}/.ds411p2pwd 0 0

Note the option vers=1.0 is newly required for Ubuntu 18.04 and the DS411+II NAS.
As root, create the above directories in /mnt. You can (as root) mount them now.

Add support for the fingerprint reader:
sudo apt install libpam-fprintd
Register your fingerprint (run as user, not root):
fprintd-enroll
Set sudo to use fingerprint scanner:
sudo pam-auth-update

Install Dot Files

Install xsane

Set up HP LaserJet MFP M477fdn with hp-setup

From within a local network, you have to use hostname.local rather than hostname for name resolution to work.

See https://en.wikipedia.org/wiki/.local

When running Meld on macOS Mojave, the Meld window will sometimes fail to appear.  The menu is there, but not the window.  Once this happens, it will stay broken until some saved state files are deleted:
rm -rf ~/Library/Saved\ Application\ State/org.gnome.meld.savedState/

The kludgey fix is to have the Meld start-up script do this for you. Add that line to /usr/local/Caskroom/meld/3.19.2-r6,osx-15/meld.wrapper.sh right before
exec '/Applications/Meld.app/Contents/MacOS/Meld' "$@"

Source: https://github.com/yousseb/meld/issues/70

The proprietary NVidia drivers for the GeForce GTX 750 are acting up again. Here’s the fix:

First verify that the wrong driver is in use:

lspci -nnk | grep -iA2 vga

01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GM107 [GeForce GTX 750] [10de:1381] (rev a2) 
    Subsystem: Micro-Star International Co., Ltd. [MSI] GM107 [GeForce GTX 750] [1462:3101]
    Kernel driver in use: nvidia

You should see nvidia as the kernel driver.  If you’re here, you probably see nouveau and maybe a few others.  Nouveau doesn’t work right with the GTX 750 and never has (and probably never will).

Download the NVidia 64-bit Linux driver.  At the time of this writing, it’s at https://www.geforce.com/drivers/results/145182

Install the driver. This is a two step process because the Nouveau driver is likely loaded by initramfs and needs to be removed. This requires a reboot.

sudo service lightdm stop
sudo sh ./NVIDIA*         # This is the driver you just downloaded
sudo update-initramfs -u  # purge nouveau driver from initramfs
sudo reboot

If your graphics are running at the right resolution, you can stop here.  If not, continue:

sudo service lightdm stop
sudo sh ./NVIDIA*
sudo service lightdm start

Source:  https://askubuntu.com/questions/823304/ubuntu-16-04-nvidia-driver-works-until-reboot