My main purpose in learning to use Ubuntu-20.4 is to run long scripts involving nmap and long text files. Trisquel_9 is my preferred operating system, as it has eliminated all the proprietary quirks, but it freezes randomly, prolonging those already long-running scripts.
Ubuntu handles the scripts OK, but the system monitor freezes at or near their completion. The good news is that the scripts go to completion anyway. I can navigate to other apps and windows, but the system monitor window can only be closed by rebooting Ubuntu.
Here's a snippet from /var/syslog.1, starting from just before the freeze:
Jun 19 16:47:10 george-ThinkPad-T420 wpa_supplicant[997]: wlxa854b2a7643d: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-64 noise=9999 txrate=1000
Jun 19 16:47:10 george-ThinkPad-T420 wpa_supplicant[997]: wlxa854b2a7643d: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-64 noise=9999 txrate=1000
Jun 19 16:47:11 george-ThinkPad-T420 wpa_supplicant[997]: wlxa854b2a7643d: CTRL-EVENT-SIGNAL-CHANGE above=0 signal=-83 noise=9999 txrate=11000
Jun 19 16:47:16 george-ThinkPad-T420 wpa_supplicant[997]: wlxa854b2a7643d: CTRL-EVENT-SIGNAL-CHANGE above=0 signal=-79 noise=9999 txrate=2000
Jun 19 16:47:17 george-ThinkPad-T420 wpa_supplicant[997]: wlxa854b2a7643d: CTRL-EVENT-SIGNAL-CHANGE above=0 signal=-89 noise=9999 txrate=2000
Jun 19 16:49:08 george-ThinkPad-T420 systemd-resolved[351]: Failed to send hostname reply: Invalid argument
Jun 19 16:49:14 george-ThinkPad-T420 NetworkManager[975]: [1624135754.0424] sup-iface[0x55afb1174100,wlp3s0]: could not get scan request result: Timeout was reached
Jun 19 16:50:14 george-ThinkPad-T420 systemd[1738]: vte-spawn-6cc6cabb-3b55-468a-92f2-cc1a6887201b.scope: Succeeded.
Jun 19 16:50:14 george-ThinkPad-T420 systemd[1738]: gnome-launched-mate-terminal.desktop-3093.scope: Succeeded.
Jun 19 16:50:41 george-ThinkPad-T420 dbus-daemon[974]: [system] Activating via systemd: service name='org.freedesktop.PackageKit' unit='packagekit.service' requested by ':1.88' (uid=1000 pid=1974 comm="/usr/bin/gnome-shell " label="unconfined")
Jun 19 16:50:41 george-ThinkPad-T420 PackageKit: daemon start
Jun 19 16:50:41 george-ThinkPad-T420 systemd[1]: Starting PackageKit Daemon...
Jun 19 16:50:59 george-ThinkPad-T420 systemd-resolved[351]: Failed to send hostname reply: Invalid argument
Jun 19 16:51:06 george-ThinkPad-T420 gnome-shell[1974]: Ignored exception from dbus method: Gio.IOErrorEnum: Timeout was reached
Jun 19 16:51:06 george-ThinkPad-T420 gnome-shell[1974]: Failed to get update info from PackageKit: Timeout was reached
Jun 19 16:51:06 george-ThinkPad-T420 gnome-shell[1974]: endSessionDialog: No XDG_SESSION_ID, fetched from logind: 2
Jun 19 16:51:11 george-ThinkPad-T420 NetworkManager[975]: [1624135871.3974] manager: NetworkManager state is now CONNECTED_SITE
Jun 19 16:51:11 george-ThinkPad-T420 whoopsie[1400]: [16:51:11] offline
Jun 19 16:51:11 george-ThinkPad-T420 dbus-daemon[974]: [system] Activating via systemd: service name='org.freedesktop.nm_dispatcher' unit='dbus-org.freedesktop.nm-dispatcher.service' requested by ':1.15' (uid=0 pid=975 comm="/usr/sbin/NetworkManager --no-daemon " label="unconfined")
Jun 19 16:51:11 george-ThinkPad-T420 systemd[1]: Starting Network Manager Script Dispatcher Service...
Jun 19 16:51:11 george-ThinkPad-T420 dbus-daemon[974]: [system] Successfully activated service 'org.freedesktop.nm_dispatcher'
Jun 19 16:51:11 george-ThinkPad-T420 systemd[1]: Started Network Manager Script Dispatcher Service.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped target GNOME Maintenance of expirable data.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: unattended-upgrades.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped target GNOME Smartcard handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped target GNOME Media keys handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-smartcard.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Smartcard handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped target GNOME RFKill handling.
Jun 19 16:51:13 george-ThinkPad-T420 kernel: [ 1898.223944] rfkill: input handler enabled
Jun 19 16:51:13 george-ThinkPad-T420 gnome-shell[1974]: gnome-shell: Fatal IO error 0 (Success) on X server :0.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: at-spi-dbus-bus.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-a11y-settings.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-datetime.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-housekeeping.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Maintenance of expirable data.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-media-keys.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Media keys handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-rfkill.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME RFKill handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-sharing.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-sound.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-usb-protection.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-wwan.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Session 2 of user george.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Removed slice system-getty.slice.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Removed slice system-modprobe.slice.
Jun 19 16:51:13 george-ThinkPad-T420 evolution-alarm[2130]: evolution-alarm-notify: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped target Graphical Interface.
Jun 19 16:51:13 george-ThinkPad-T420 xdg-desktop-por[2399]: xdg-desktop-portal-gtk: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.
Jun 19 16:51:13 george-ThinkPad-T420 nautilus[2678]: org.gnome.Nautilus: Fatal IO error 2 (No such file or directory) on X server :0.
Jun 19 16:51:13 george-ThinkPad-T420 update-notifier[2926]: update-notifier: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped target Multi-User System.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped target Login Prompts.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped target Sound Card.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped target Timers.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: anacron.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Trigger anacron every hour.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: apt-daily-upgrade.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Daily apt upgrade and clean activities.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: apt-daily.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Daily apt download activities.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: e2scrub_all.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Periodic ext4 Online Metadata Check for All Filesystems.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: fstrim.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Discard unused blocks once a week.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: fwupd-refresh.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Refresh fwupd metadata regularly.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: logrotate.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Daily rotation of log files.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: man-db.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Daily man-db regeneration.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: motd-news.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Message of the Day.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: systemd-tmpfiles-clean.timer: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped Daily Cleanup of Temporary Directories.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: systemd-rfkill.socket: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Closed Load/Save RF Kill Switch Status /dev/rfkill Watch.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-color.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Color management.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-keyboard.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Keyboard handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-power.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Power management handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-print-notifications.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Printer notifications.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-screensaver-proxy.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Freedesktop screensaver handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-wacom.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME Wacom handling.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: gsd-xsettings.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: Stopped GNOME XSettings.
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "22"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event2 - Power Button: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "25"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event8 - Video Bus: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "26"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event1 - Sleep Button: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "27"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event9 - Integrated Camera: Integrated C: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "28"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event4 - PixArt USB Optical Mouse: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "29"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event3 - AT Translated Set 2 keyboard: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "30"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event5 - SynPS/2 Synaptics TouchPad: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: () Option "fd" "31"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event6 - TPPS/2 IBM TrackPoint: device removed
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (**) Option "fd" "32"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) event7 - ThinkPad Extra Buttons: device removed
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: xdg-desktop-portal-gtk.service: Main process exited, code=exited, status=1/FAILURE
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1738]: xdg-desktop-portal-gtk.service: Failed with result 'exit-code'.
Jun 19 16:51:13 george-ThinkPad-T420 ModemManager[1064]: Caught signal, shutting down...
Jun 19 16:51:13 george-ThinkPad-T420 ModemManager[1064]: ModemManager is shut down
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Modem Manager...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Network Manager Script Dispatcher Service...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Accounts Service...
Jun 19 16:51:13 george-ThinkPad-T420 nm-dispatcher: Caught signal 15, shutting down...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping ACPI event daemon...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Save/Restore Sound Card State...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping LSB: automatic crash report generation...
Jun 19 16:51:13 george-ThinkPad-T420 bluetoothd[971]: Terminating
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Bluetooth service...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Manage, Install and Generate Color Profiles...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Regular background program processing daemon...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Make remote CUPS printers available locally...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping GNOME Display Manager...
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) UnloadModule: "libinput"
Jun 19 16:51:13 george-ThinkPad-T420 /usr/lib/gdm3/gdm-x-session[1825]: (II) systemd-logind: releasing fd for 13:71
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping LSB: Record successful boot for GRUB...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping irqbalance daemon...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Tool to automatically collect and submit kernel crash signatures...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopping Dispatcher daemon for systemd-networkd...
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: openvpn.service: Succeeded.
Jun 19 16:51:13 george-ThinkPad-T420 systemd[1]: Stopped OpenVPN service.
I've since installed gnome-tweaks, following one respondent's suggestion.
