i really like the following tools:
lsd aka ls deluxe - a nicer ls
btop - an incredible system monitor able to show gpu usage
chafa - shows pictures in your terminal
cava - an audio visualizer
mc aka midnight commander - the swiss army knife of shells
jq - lets you edit and query json data

provided that you already having an ics or html calendar source added to nextcloud calendar:

sudo -u www-data php -f /var/www/nextcloud/occ config:app:set dav calendarSubscriptionRefreshRate --value "PT600S"

this makes it refresh the calendar every 10 minutes. or you don't do that and wait for a week.

go to

cd ~/.local/share/applications/
touch myprog.desktop

fill the file with s.th. like

[Desktop Entry]
Name=Unison (sc)
Comment=synchronize files
Exec=/usr/local/bin/unison-gtk
Icon=unison-gtk
Terminal=false
Type=Application
Categories=System;

save, now run

update-menues

after installing the citrix workspace app run

sudo ln -s /usr/share/ca-certificates/mozilla/* /opt/Citrix/ICAClient/keystore/cacerts/

since unison doesn't work with different versions, just accept that you have to build this from scratch, since the next os upgrade of one of the involved clients will break protocol.

sudo apt install opam ocaml liblablgtk2-ocaml-dev liblablgtk2-ocaml

labelgtk* isn't needed for cli version only and can be skipped in the opam steps, too.

opam init
eval $(opam env)
opam switch create ocaml-base-compiler.4.05.0
eval $(opam env)
opam install lablgtk

we download the unison 2.51.2 source. unzip it somewhere and cd into it. for the gtk version you need to hack src/uigtk2.ml before and replace in line 97 from region_of_string to region_of_bytes.

make

this compiles now the gtk2 version. if cli is needed:

make text

beware that the binary has the same name. make will automatically generate cli version if lablgtk is not installed.
now copy the files to your systemfolder

sudo cp src/unison src/unison-fswatch /usr/bin/
cd /usr/bin
sudo ln -s unison unison-2.51

on older opam versions (1.x), like on raspbian stretch, things look a little bit different:

opam init
eval $(opam config env)
opam switch set 4.05.0
eval $(opam config env)
cd yourunisonsourcedirectory
make

precompiled versions can be found here:
unison-gtk 2.51.2-ocaml4.05.0 binary[x64]
unison 2.51.2-ocaml4.05.0 binary[x64]
unison-fsmonitor 2.51.2-ocaml4.05.0 binary[x64]
unison 2.51.2-ocaml4.05.0 binary[armhf]
unison-fsmonitor 2.51.2-ocaml4.05.0 binary[armhf]

check .pem / check .crt

openssl x509 -noout -text -in certificate.pem

check .csr

openssl req -noout -text -verify -in cert_sign_req.csr

convert p12 to pem

openssl pkcs12 -in certificate.p12 -nocerts -out certificate.key
openssl pkcs12 -in certificate.p12 -clcerts -nokeys -out certificate.crt
cat certificate.crt certificate.key > certificate.pem

in case the key is still encrypted after extracting it run

openssl rsa -in certificate.key -out certificate_decrypted.key

check if key belongs to certificate

openssl x509 -modulus -noout -in server.com.crt | openssl md5
openssl rsa  -modulus -noout -in server.com.key | openssl md5

you want to log off but some job is still running in the background

disown -a && exit

youtube isn't working.
go to /usr/lib/x86_64-linux-gnu/opera and replace the libffmpeg.so with the chromium one.
since ubuntu now only ships snaps, we need to get the download location of that package.

curl -H 'Snap-Device-Series: 16' http://api.snapcraft.io/v2/snaps/info/chromium-ffmpeg | jq

get the download url for your architecture by hand. next one is an example. then mount the package and get the libffmpeg.so from the latest chromium-folder (there are plenty)

wget https://api.snapcraft.io/api/v1/snaps/download/XXzVIXswXKHqlUATPqGCj2w2l7BxosS8_24.snap
sudo mount -t squashfs -o ro XXzVIXswXKHqlUATPqGCj2w2l7BxosS8_24.snap /mnt/
sudo cp /mnt/chromium-ffmpeg-104707/chromium-ffmpeg/libffmpeg.so /usr/lib/x86_64-linux-gnu/opera/

as Bash user, simply fill your $HOME/.bash_aliases with stuff like:

# some more ls aliases
alias l='/usr/bin/ls -CFlh'
alias ls='lsd'
alias ll='ls -lAh'
alias la='ls -Ah'

alias ..='cd ..'
alias cd..='cd ..'
alias m:='cd /media/gerrit'
alias r:='cd /resources'
alias u:='cd /resources/_user'
alias acmd='amulecmd -P h0ll4nd'
alias createdeb='checkinstall -D'
#krass gut dupletten komprimieren
alias compressdubs='7za a -t7z -m0=lzma2 -mx=9 -mfb=273 -md=32 -ms=8g -mmt=16 -mmtf=off -mqs=on -bt -bb3'
alias delete_thumbs='rm -r ~/.thumbnails/*; python ~/bin/g3bookmarks.py'
alias dfh='df -hlTx tmpfs | ( read header ; echo "$header" ; sort -k 7 -i)'
alias dirtree='tree -fi'
alias md='mkdir'
alias agi='sudo apt-get install'
alias acs='sudo apt-cache search'
alias agu='sudo apt-get update && sudo apt-get upgrade'
alias agd='sudo apt-get update && sudo apt-get dist-upgrade'
alias publicip='curl https://schrottrecorder.com/ip/raw 2>/dev/null'
alias uuids='lsblk -o UUID,MOUNTPOINT,PATH,SIZE'
youtube-url () { yt-dlp -j ytsearch1:"$1"|jq '.webpage_url' | tr -d '"' ; }
alias y='yt-dlp --merge-output-format mp4 --format "bestvideo[ext=mp4][vcodec!*=av01]+bestaudio[ext=m4a]" --add-metadata'

sox_duration_total () {
  if [[ "$#" -lt 1 ]]; then
    echo "find files!"
    echo "  sox_duration_total *.mp3"
    echo ""
    return
  fi
  for i in "$@"; do
    val=$(soxi -d "$i")
    echo "$val | $i"
  done
  soxi -D "$@" | python -c "import sys;print(\"\ntotal sec:    \" +str( sum(float(l) for l in sys.stdin)))"
  soxi -D "$@" | python -c "import sys;print(\"total min:    \" +str( sum(float(l) for l in sys.stdin)/60 ))"
  soxi -D "$@" | python -c "import sys;import datetime;print(\"running time: \" +str( datetime.timedelta(seconds=sum(float(l) for l in sys.stdin)) ))"
}

alias please='sudo'
alias gitreset="git fetch origin master;git reset --hard origin/master"

#Do compression with all cores !!
function gzip(){ pigz $@; }
function gunzip(){ unpigz $@; }
function bzip2(){ pbzip2 $@; }
#function bunzip2(){ pbunzip2 $@ }
#function xz(){ pxz $@ }

alias mpl='mpv'
alias mplf='mpl -fs'
alias mpls='mpl -shuffle'
alias mplfs='mpls -fs'

#alias ffmerge='ffmpeg -acodec copy -vcodec copy'
ffmerge () { ffmpeg -i "$14a" -i "$1p4" -c:v copy -c:a aac -strict experimental "$1.mp4"; }
efs () { encfs `pwd`/$1 `pwd`/$2; }
ufs () { fusermount -u $1; }
torrent () { case $1 in
    "add")      transmission-remote -a $2;;
    "del")      transmission-remote -t $2 -r;;
    "wl")       watch transmission-remote -l;;
    "watch")    watch transmission-remote -t $2 -i;;
    "list")     transmission-remote -l;;
    "start")    transmission-remote -t $2 -s;;
    "stop")     transmission-remote -t $2 -S;;
    *)          echo "Usage: torrent add/del/watch/list \$params";;
    esac; }

if [ $TERM == "dumb" ]; then export TERM=xterm; fi

alias wine_oblivion='export WINEPREFIX=/ssd2/.steam/steam/steamapps/compatdata/22370/pfx'
alias wine_f4='export WINEPREFIX=/ssd2/.steam/steam/steamapps/compatdata/377160/pfx'

alias visualizer=cava
alias showpic=chafa

PS1='\[\e]0;\h \w\a\]\n\[\e[48;5;33m\] \[\e[0m\] \[\e[38;5;33m\]\u\[\e[38;5;33m\]@\[\e[38;5;33m\]\h\[\e[32m\] \[\e[38;5;33m\]\w\n\[\e[0;48;5;45m\] \[\e[0m\] \[\e[38;5;38m\]\t\[\e[0m\] \$ '

start/stop the mediacenter

sudo systemctl {start/stop} mediacenter

videolibrarycontrol. command={Clean,Scan}

curl --data-binary '{ "jsonrpc": "2.0", "method": "VideoLibrary.{command}", "id": "mybash"}' -H 'content-type: application/json;' http://localhost:8080/jsonrpcr

same for audiofiles...

curl --data-binary '{ "jsonrpc": "2.0", "method": "AudioLibrary.{command}", "id": "mybash"}' -H 'content-type: application/json;' http://localhost:8080/jsonrpcr

finally exporting the library via xbmc-senc

xbmc-send -a "exportlibrary(video,false,your_backup_path)"