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Month: March 2021

control-click on a vnc session from a mac

Published by jweisber on 2021-03-04

Without control-(mouse) click, a lot of functionality is lost.  I have finally figured out how to geve the equivalent of it on a mac, when running a vncviewer window on the mac.

On the mac, go to apple>>system preferences>>Trackpad>>Secondary click.

Under the Trackpad pane;’s “Secondary Click” are:
–A check box –   check it.
–A pulldown menu under “Secondary Click” where you can choose what action will represent the control-click. I chose “click in bottom left corner.”

And indeed, when I click trackpad in lower left corner on a VNCviewer session, the vnc session responds as if I had hit control-click.

setting up your centos7 desktop after machine was upgraded to that os

Published by jweisber on 2021-03-04

These notes are mostly from Bruce. The original is at /docs/centos7/

Centos 7 Gnome UI configuration
====================================================================================================

CentOS 7 comes with some UI changes from the centos6 experience that you may wish to adjust.

See below for concrete examples below for commonly changed settings.

Generally speaking, there are 4(!) tools that allow you to adjust aspects of your UI environment. 3
via the System Menu (Upper Left corner of your screen) and 1 via the ‘gsettings’ shell CLI.

Determing which of these 4 tools provides the setting you want to change can be challenging. It’s
often easiest just to google for “centos 7 change <???> settings” to find out which one[s] to use
for the given setting you want to change.

The 4 ways to change the UI:

1) “Applications > Tweaks > XXX”

This brings up the ‘Gnome Tweak Tool’ that lets you set a bunch of things.

Example:

Applications > Tweaks > Keyboard & Mouse >

let’s you map the Caps Lock key to an additional Ctrl key (see below)

2) “Applications > System Tools > Settings > XXX”

Example:

Applications > System Tools > Settings > Privacy > Screen Lock

3) “Applications > System Tools > dconf Editor”

This is a bare-bones editor that enables you to get/set the same tree of settings that can be
manipulated by the ‘gsettings’ CLI below, which is a superset of what can be changed via the
Gnome Tweak Tool above.

org/gnome/desktop/screensaver/lock-delay
org/gnome/desktop/interface/text-scaling-factor

4) The ‘gsettings’ Shell (Terminal Window) command:

This is the shell get/set CLI for the dconf Editor above

Examples:

$ gsettings get org.gnome.desktop.screensaver lock-delay
uint32 300
$ gsettings set org.gnome.desktop.screensaver lock-delay 600
$ gsettings get org.gnome.desktop.screensaver lock-delay
uint32 600
$

Sources:

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/gsettings-dconf

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/browsing-gsettings-values-for-applications

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/configuration-overview-gsettings-dconf

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/desktop_migration_and_administration_guide/browsing-gsettings-values-for-applications

 

====================================================================================================
Specific examples
====================================================================================================

—————————————————————————————————-
Put App shortcuts on the desktop
—————————————————————————————————-

You can click-and-drag any of the app icons from any submenu of the main ‘Applications’ menu to the
desktop and then launch it from there.

—————————————————————————————————-
Put App shortcuts on the ‘top panel’
—————————————————————————————————-

I haven’t found a way to do this yet.

—————————————————————————————————-
Shrink Desktop Icon size
—————————————————————————————————-

Desktop Icons are stupidly large. Fix with

# gsettings set org.gnome.nautilus.icon-view default-zoom-level small

—————————————————————————————————-
Font sizes used on the screen are oversized
—————————————————————————————————-

Make fonts smaller via

Applications>Accessories>Tweaks>Fonts>Scaling Factor -> 0.90

—————————————————————————————————-
Make menu clock show the Date and Seconds
—————————————————————————————————-

Applications > Tweaks > Top Bar

Under ‘Clock’ header

Controls how clock appears in screen’s top menu bar

Date [on|off]
Seconds [on|off]

—————————————————————————————————-
Configure Startup Applications
—————————————————————————————————-

You can specify what applications you want to have launched at login.

Applications > Tweaks > Startup Applications

Select the apps you want to run at startup.

—————————————————————————————————-
Make ‘Caps Lock’ key an additional ‘Ctrl’ key
—————————————————————————————————-

Very useful for emacs users.

NOTE: Make sure Caps Lock is not active when you do this!

Applications > Tweaks > Keyboard & Mouse >

Under ‘Keyboard’ heading, select the ‘Additional Layout Options’ button.

In the ‘Additional Layout Options’ window that pops up, select the ‘Caps Lock Behavior’ ‘triangle’
button and then select ‘Caps Lock is also a Ctrl’.

—————————————————————————————————-
Adjust the screensaver lock timer
—————————————————————————————————-

The screensaver lock timer is very aggressive. To adjust, open “Applications > System Tools >
Settings > Privacy > Screen Lock”

In the ‘Screen Lock’ window you can select the ‘Lock screen after blank for’ value from ‘Screen
Turns Off’ to a number of minutes, such as 1, 2, 5, or 30 minutes (but not anything between 5 and 30
minutes which is odd).

If you want to set the timer to values between 5 <-> 30 minutes, you can use the ‘gsettings’ CLI.

Here’s how to do it via ‘gsettings’:

From the terminal (to set sleep timeout to 10 minutes / 600 seconds,
then require login after 15 minutes / 900 seconds):

gsettings set org.gnome.settings-daemon.plugins.power sleep-display-ac 600
gsettings set org.gnome.settings-daemon.plugins.power sleep-display-battery 600
gsettings set org.gnome.desktop.session idle-delay 600
gsettings set org.gnome.desktop.screensaver idle-activation-enabled ‘true’
gsettings set org.gnome.desktop.screensaver lock-enabled ‘true’
gsettings set org.gnome.desktop.screensaver lock-delay 900

—————————————————————————————————-
Set prefs for Nautilus (File Manager)
—————————————————————————————————-

Open ‘Applications > File Manager’ from the menu in the Upper Left of your screen.

The Nautilus File Manager should open.

In the top menu bar you should now see the ‘Files’ menu item

From the ‘Files’ menu, select ‘Preferences’

—————————————————————————————————-
Set prefs for Konqueror (File Manager): Joel notes that konqueror file manager is back, after being missing from centos6.  I like konqueror much more than nautilus (it shows link targets, a particular issue of mine.)  So I set it up on centos7.  Rather than telling you all the miriad of settings I needed to select and change, how about you just ask me to tell you all the settings if you are interested (ie if you are frustrated with nautilus)
—————————————————————————————————-
—————————————————————————————————-
Update Firefox UI “Experience”
—————————————————————————————————-

When you launch Firefox it will ask you if you want to update your ‘experience’. Say ‘yes’ and it
will relaunch but show the latest UI.

—————————————————————————————————-
Configure the GV.printCommand:
—————————————————————————————————-

GV’S print command dialog window has a type-in labeled ‘print command’ and it’s automagically
populated with the string ‘lpr’. However you can change that string to ‘ps2pdf %s – | lpr’. You
can also change the default print string from ‘lpr’ to whatever you want in GhostScript options, but
that would break printing of non .ps files.

To change the default print string in ‘gv’, select:

State->Setup Options

… Look for the Print Command field, and change the value from
‘lpr’ to ‘ps2pdf %s – | lpr’ (w/o the single quotes).

The change is saved to ~/.gv as the line:

GV.printCommand: ps2pdf %s – | lpr

Ssh security

Published by jweisber on 2021-03-04

Directions from Bruce. (BDUFFY 2021-02-17. )Thanks Bruce! Slightly updated by Joel. These were specifically for setting up to ssh to new mirzam, but are relevant for any new host.

Remove old mirzam entries from your ~/.ssh/known_hosts file  (It looks like very long lines of gibberish. A hostname or its internet number [ie 137.22.301.5] starts each line.)

The next time you ssh into to an astronet machine, ssh will ask you

(base) bduffy66924:~ bduffy$ ssh bduffy@mirzam.physics.carleton.edu
The authenticity of host ‘mirzam.physics.carleton.edu (137.22.6.129)’ can’t be established.
ECDSA key fingerprint is SHA256:nersU93cf8F5ucysog/Rn2OIbSabknw10hpw5uXFs3o.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘mirzam.physics.carleton.edu’ (ECDSA) to the list of known hosts.
bduffy@mirzam.physics.carleton.edu: Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
(base) bduffy66924:~ bduffy$

See ./astronet-server-ssh-public-keys.txt

2021 05 17:  JMW does not know what directory ^ this is in.

Also, I had to add the authorized_keys file to one of my home macs’ .ssh directory in order to get all the way in to canopus.  See email from Bruce on 2021 05 17 for more details.