knowledge

references for linux admin and development

---

• ai misc
• csharp
• shell
• development tools
• c++
• database
• webdevel
• electronics
• general development
• gis
• math
• sysadm
• networking
• python
• linux
• security
• mobile native
• tools
• media

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ai misc

angular

• angular rxjs best practice change field of an object directly on the behaviorsubject then call next or work on a clone then next
• angular set multiple behaviorsubject at once
• angular pipe recompute on rxjs event
• angular prevent dialog from close clock outside
• angular directive to track size and position of an element included begin values and margins
• angular combineLatest skip when next equals previous
• angular htmldivelement create a canvas at runtime
• angular two way binding property
• angular get only innertext from a string containing html tags
• angular ngx-leaflet map add custom control
• angular gsap circle that follow mouse and drop circle where click happens
• angular directive elementRef become undefined under mouse click event handler

typescript

• typescript full qualify Map type name
• typescript print difference between two json
• typescript Date to locale string with dayname abbrev day number and month abbrev with custom timezone
• typescript invoke static method using this
• typescript parse json date only string YYYY-MM-DD to date object assuming italy timezone with time 00:00
• typescript create ICAL event with location latitude and longitude

csharp

• c# parse month name with italian locale

css

• css div shadow blur

csharp

• c# ensure an async Task started and reached a region before to proceeed with other instructions
• csharp difference between != and is not null

---

csharp

• language notes
• send email 465
• dotnet scripts
• member not null
• task programming
• dotnet core
  • publish self contained dotnet publish -c Release --runtime linux-x64 --sc
  • dotnet3 and 5 on ubuntu20.04
  • dotnet6 and 7 on ubuntu24.04
  • netcore csproj ( generate doc, copy to output, define macro, exclude files from compile, disable warnings )
  • test coverage
  • view unit test output logger : open Output and select C# Dev Kit - Test Explorer
  • netcore platform environment ( os type, debug macro )
  • asp net core
  • dotnet sdks - installers
  • dotnet cmdline
  • dotnet core unix interop
  • dotnet gui
    • uno
    • avalonia
      • notes
      • app icon
      • vscode xaml intellisense
  • dotnet netcorestandard testunit
  • troubleshoot
  • view version of dll exiftool file.dll | grep 'Product Version'
• regex
• csharp to typescript
• xlsx finalize worksheet freeze columns
• wpf
• tuple value read write
• read from special serial ttyACM cdc type
• trap ctrl+c
• c# coding standards
• ef core
  • disable validation for some prop [ValidateNever] attribute
  • psql ef codefirst
  • transaction
• opengl
  • silk net under virtualbox opengl3.3
• user secrets

shell

• bash
  • bash scripting
  • bash locale
  • prompt colors
• executing dir in bash script exdir=$(dirname "$(readlink -f "$BASH_SOURCE")")
• text screencast
  • ttyrec ttygif
  • asciinema
• find files sorted by size find -type f -name "*.pdf" -printf '%s\t%p\n' | sort -nr | less
• linux scripts
• trap control+c
• function arguments expansion
• formatted print
• diff huge files
• find xargs and exec
• get file size
• file age sec
• elapsed seconds date
• terminal color
• escape html
• uri encode
• jq json tool
• ensure kill process
• ls in mb ls -la --block-size=MB
• monitor progress of pipe cat /dev/random | pv > /dev/null
• sed
  • replace newline
  • skip first line cat file | sed -n '1d;p'
  • skip line range sed A,Bd file ( skip lines with index range [A,B] )
  • delete empty lines cat file | sed -r '/^\s*$/d'
• time
  • GMT TZ=GMT date +@GMT-%Y.%m.%d-%H.%M.%S
  • time from unixtime date -d @VALUE
• show dialog notification notify-send title msg
• short uuid

development tools

• opensource dev
• git
  • git
  • git animate
  • github git ssh
• run github action workflows locally
• fast gui diff fldiff file1 file2
• api docfx
• mono
• perf
  • dotnet trace
  • trace x11 (xtrace -n cmd args)
• vscode
  • tips
  • keybinding
  • fold functions
  • settings
  • useful extensions
  • troubleshoot
  • react debug chrome
  • debug firefox
  • show external code
  • remote host through docker
• gnome development
• nuget
  • linux-install
  • local packages
  • troubleshoot
  • msbuild: dotnet msbuild
  • search pkgs command line
• docx documentation generator
• librecalc
• dump c++ symbols from .so lib nm -gDC LIB.so
• graphics
  • gnuplot
  • debug opengl programs apt install renderdoc
• get PID from window xprop | awk '/PID/ {print $3}'
• limit cpu apt install cpulimit ; cpulimit -p PID -l 5 ( limit process PID to 5% )

c++

• clang format
• linux vscode debug
• dump-file-to-c

database

• System.Linq.Dynamic.Core
• create db server using docker
• postgres
  • create psql container
  • backup restore
  • password in file
  • select datetime timezone
  • pgadmin install docker run --restart=unless-stopped --name=pgadmin -p 8080:80 -e 'PGADMIN_DEFAULT_EMAIL=email' -e 'PGADMIN_DEFAULT_PASSWORD=pass' -d dpage/pgadmin4
  • index array
  • sequence schema
  • create db and assign user
• mssql
  • docker local mssql server
• diagramming schema
  • schema crawler
  • automatic generate psql db diagram
• entity framework
  • load related entities

webdevel

• odata
• ts hello world
• javascript/jquery
  • momentjs date
• bootstrap css
• sandbox repro
• chrome
• imagemap ( just use gimp Filters/Web/Imagemap )
• grunt troubleshoot
• css
  • padding 1-4 values
    • 1 value ( all sides equal )
    • 2 value ( top/bottom left/right )
    • 3 value ( top left/right bottom )
    • 4 value ( top, right, bottom, left )
• npm
  • tips
  • proxy cache
• typescript
  • create console app
  • support for optional chaining conditional ? operator (upgrade react-scripts to 3.3.0)
  • troubleshoot
• react / material.ui ( typescript )
  • examples
  • snippets
  • create react typescript npm create vite@latest test-app -- --template react-ts
  • app skeleton and global states
  • create react library useHook error
  • resposive drawer with styles and theme
  • common styles combined

electronics

• arduino
  • vscode arduino
  • vscode arduino platformio
    • atmega328
    • atmega8
    • platformio troubleshoot
  • vscode arduino nano platformio
  • arduino on atmega8
  • atmega power save
  • arduino examine elf
  • esp8266 board plugin ( use http://arduino.esp8266.com/staging/package_esp8266com_index.json for development )
  • esp8266 twi arduino nano problems
  • esp8266 tips
  • serial baud rate
• stm32
  • vscode debugging
  • string stream
  • tips
  • multiple devices
• schematics and pcb editor
• circuit simulator
  • circuitjs
  • qucs
  • everycircuit
• pcb etching
• transistor biasing
• measure usb cable resistance
• UM34C linux log
• 3d print tips

general development

• references

gis

• geojson

math

• c# AngouriMath symbolic
• octave symbolic

sysadm

• backup imap
• boot win phydisk

networking

• wired hotspot
• get current public ip address curl -s ifconfig.me
• netplan yaml ref
• ubuntu desktop disable network manager
• ssh
  • ssh misc
  • ssh ctrl channel
  • ssh mount dir
• send a tcp packet echo sample | nc 10.10.2.10 1000
• test tcp port echo "test" | netcat -w 5 -W 1 host port ; if [ "$?" == "0" ]; then echo "OK"; else echo "UNREACHABLE"; fi
• test webapi
• send simple message over udp
• send email
• nginx
  • tune nginx for webapi
  • exec shell script with fastcgi
• wireshark
  • run wireshark as nonroot
  • wireshark chrome decrypt ssl
• https proxy sniffer
• xrdp remmina
• zimbra
  • force smtp auth
  • backup/restore mailbox
• mobile server
• samba
  • get ip from netbios name nmblookup <name>
  • scan netbios name in net nbtscan <netaddr>
• monitor interfaces bandwidth bmon -p eth0,eth1 or nload -m
• quick list interface addresses ip -br a
• ethernet cabling T568A T568B
• scan hostnames nmap -sn addr/mask
• bluetooth
• tcpdump
  • cheat sheet
  • examples
• cert fingerprint
• retrieve bandwidth utilization continously for given interface with ifstat -i devname
• download remote http folder wget -r --no-parent URL
• x11vnc headless

python

• plotting
  • plot 2d 2var function
• calc
  • solve eq

linux

• server
  • quick and dirty virtualized vlan os install notes
  • quick and dirty os install notes
  • prevent unattended upgrades
  • resize lvm cache in favor of swap partition
  • ubuntu server post install
  • custom boot script
  • disable sleep
  • systemd services
  • zfs
  • how much is wear ssd
  • netfilter
  • self signed cert
  • journalctl
  • crontab
  • wake-on-lan
  • test cpu speed apt install sysbench ; sysbench cpu run then see events per seconds ( higher better )
  • detached screen
  • nfs4 acl
  • chroot env
  • rescue notes
• kde
  • disable input method completion
• gnome
  • shell extension with bash
  • fix sort icon direction
  • custom open with
  • desktop icons
  • gnome bookmarks
  • reload shell with top panel killall gnome-shell
  • always on top apt install compiz-plugins
  • chrome freeze when attach files ( could try apt install xdg-desktop-portal-gnome to change file dialog )
• devices
  • cpu bench sysbench --threads="$(nproc)" cpu run
  • kubuntu enable touchpad tapping
  • udev rules
  • nautilus file manager folder right click -> open in terminal apt install nautilus-open-terminal
  • hardware inventory inxi
  • minisforum UM773 LITE - F7BFD graphics drivers
• log
  • tail generic color
  • colourized log grc --colour=on tail -f /var/log/syslog
  • grep only in file pattern grep -r --include="*.EXT" <search-string> <beginpath>
  • tail grep continous
  • force log rotate
• remotely assist linux can't boot
• ubuntu pendrive custom kernel arg
• flash win bootable pendrive
• monitor disk temperature
• tune inotify watches
• disable oom killer
• fix dual boot
• su with sudo colorful prompt
• i18n decimal separator dot
• draftsight open dxf
• packages
  • packages build dep
  • dpkg
  • upgrade single package apt-get install --only-upgrade package
  • retrieve list of upgradable packages apt list --upgradable
  • retrieve version current and older apt-cache policy package
  • install old version apt-get install package=version
• processes
  • show process memory graph smem --pie=name
  • process management
  • autorespawn process using supervisor
  • show memoy usage smem --pie name -s rss
• ubuntu tune
  • locale and timezone
  • kubuntu 22.04
  • ubuntu 22.04 tune
  • ubuntu 20.04 tuf gx505
  • ubuntu 20.04 asus P2550
  • disable tracker miner
  • ubuntu 19.04
  • ubuntu 18.04
  • directory color on dark theme, set /etc/bash.bashrc with export LS_COLORS='di=0;34:ow=1;34'
• virtualization
  • virsh storage
  • virsh tips and backup
  • virtualbox
  • set virtualbox guest motherboard-cpu-id
  • copy qcow2 over network rsync --sparse --inplace -zv --progress src.qcow2 dst:folder
• remove desktop
  • fix Authentication Required to Create Managed Color Device ref
• strip log
• devices
  • card reader
  • bit4id minilector evo driver 64bit
  • wacom inkscape pressure
  • epson scanner gt-s50
  • usb and udev
• disks
  • raid
    • autotune raid reconstruction speed
    • raid management
    • replace raid md damaged disk
  • loopback devices
  • monitor disks activity iostat -dx 5 or for device (mb/s) iostat -sm -p /dev/DEVICE 1
  • create bootable iso
  • force reread partition : partprobe <device>
  • create uefi usb from iso
  • encrypt disk
  • selfcheck disk health
  • disk space analyzer apt install baobab
  • compare two directories diff -rq DIR1 DIR2
• files
  • search duplicate files find . ! -empty -type f -exec md5sum {} + | sort | uniq -w32 -dD > dupfiles.txt
• docker containers
  • docker xwindows
  • modify created docker env
  • docker buildx
  • docker registry
  • docker without iptables
  • docker backup
  • show layer commands
  • doc not included ( see /etc/dpkg/dpkg.cfg.d/excludes )
  • test swap memory
  • scripts ( dk-id, dk-purge-log, dk-net, ... )
  • add xrdp to docker container
  • btrfs tools
  • tail log continously docker logs -f CONTAINER | grep --line-buffered -ia WORD
  • run gitlab ci from terminal
• battery nfo
• nextcloud
  • tips
  • rclone
• fonts
• general
  • firefox

security

• gpg
• iptables firewall
• generate htpasswd
• cert management
• id_rsa
• letsencrypt acme dns
• fail2ban
• passbolt

mobile native

• intellij android studio
• android push notify

tools

• development
  • convert json to csharp
• cygwin install
• win10 quick assist
• drawings
  • dwg viewer
  • dxf editor qcad
  • draftsight troubleshoot
• document
  • translator
  • xlsx
  • nano editor
  • github latex math
  • hex editor : bless
  • markdown refs
  • markdown toc
  • markdown to pdf
  • markdown server
  • useful unicode
  • google drive direct link https://drive.google.com/uc?export=download&id=DRIVE_FILE_ID

media

• editing
  • pdf edit inking apt install xournal
  • pdf join into single page
  • convert jpg to pdf convert *.jpg -auto-orient out.pdf
• sound
  • console player apt install mocp
• tv
  • kaffeine apt install kaffine w-scan
• graphics
  • test 3d working
  • qrcode
  • screen cast gif
  • freecad
    • troubleshoot svg import
    • tips
  • image info identify image.jpg
  • crop image convert input.jpg -crop wxh+x+y out.jpg
  • resize image
  • video transcoding
  • remove image exif
  • grab screen to image
  • ubuntu cast to chromecst apt install mkchromecast
  • show opengl limits glxinfo -l
  • compare two images compare -metric AE image1.png image2.png diffout.png
  • create favicon
• misc
  • stream dvbt to chromecast