[RPi] 改變啟動視窗的位置

這篇好像可以解決, 又似乎不行 QQ
https://askubuntu.com/questions/613973/how-can-i-start-up-an-application-with-a-pre-defined-window-size-and-position

這篇看起來是原生的功能, 但試起來也是不行 QQ
https://askubuntu.com/questions/107951/how-to-set-a-specific-window-size-and-placement-for-all-windows-that-open-to-def

這篇看來最實用 QQ
https://askubuntu.com/questions/452995/how-to-adjust-window-placement-in-unity-ubuntu-14-04-based-on-overlapping-top-b

I have the same issue too. I avoided it simply using the shortcut Alt + Left Mouse Click to move the window.

[RPi] 不用密碼就登入

每次都忘記, 紀錄一下

ssh-keygen -t rsa

把 raspberrypi.local 換掉就可以了

cat ~/.ssh/id_rsa.pub | ssh pi@raspberrypi.local 'mkdir .ssh/ && cat >> .ssh/authorized_keys

https://www.jaredwolff.com/blog/passwordless-ssh-raspberry-pi/

[RPi] 簡單分辨 Pi 3 和 Pi 2

source: element14

$ cat /proc/cpuinfo

[ROS] 紀錄一些有用的連結

Code and examples for Learning ROS for Robotics Programming - 2nd Edition
https://github.com/AaronMR/Learning_ROS_for_Robotics_Programming_2nd_edition

[RPi] Ubuntu Mate

最近在搞 ROS, 參考別人使用 Ubuntu Mate 環境, 但有點不熟練, 紀錄一下好了

1. 預設帳號密碼 ubuntu/ubuntu

2. 和 Raspbian 一樣要設定 /boot/config.txt 才能從 UART 登入

$ sudo vim /boot/config.txt

---
dtoverlay=pi3-miniuart-bt
core_freq=250
enable_uart=1
---

3. WiFi 設定

$ sudo apt-get install wireless-tools
$ sudo apt-get install wpasupplicant
$ sudo vim /etc/network/interfaces
---
auto wlan0
iface wlan0 inet dhcp
wpa-essid WIRELESSSSID
wpa-psk WIRELESSPASSWORD
---
$ reboot
以上是固定 SSID 作法


如果要像 Raspbian 使用 wpa_supplicant 管理的話, 要這樣做

$ sudo vim /etc/network/interfaces
---
auto wlan0
iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
---

而 /etc/wpa_supplicant/wpa_supplicant.conf 就像原本 Raspbian 設定的一樣了
---
country=GB

network={
    ssid="MyWifiNetwork"
    psk="myP4ssw0rd"
}
---

如果要用 x11vnc 的話, 也稍微麻煩一些

$ sudo vim /lib/systemd/system/x11vnc.service
---
[Unit]
Description=Start x11vnc at startup.
After=multi-user.target

[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -auth guess -forever -loop -noxdamage -repeat -rfbauth /etc/x11vnc.pass -rfbport 5900 -shared

[Install]
WantedBy=multi-user.target
---

$ sudo chmod +x /lib/systemd/system/x11vnc.service
$ sudo systemctl daemon-reload
$ sudo systemctl enable x11vnc.service
$ sudo systemctl start x11vnc.service


如果要改成不要輸入密碼, 修改 /etc/sudoers
$ sudo vim /etc/sudoer
---
-%sudo   ALL=(ALL:ALL) ALL
+%sudo   ALL=(ALL:ALL) NOPASSWD:ALL
---

reference:
* How to use onboard wifi on Raspberry Pi 3 with Ubuntu Server 16.04?
* Ubuntu 16.04 – Configure your system to have x11vnc running at startup

[Tips] 分散式CMAKE(待測)

之前用過 distcc 編譯小的函式庫, 有時候快有時候慢

最近開始做 ROS, 編譯 190 個套件要數個小時(>3), 該試試看用 distcc 會不會改善吧
http://pointclouds.org/documentation/advanced/distcc.php

[資訊科學] Multiprocessing, Multithreading,HyperThreading, Multi-core

這幾篇一定要看一下的

1. Threads & Processes Vs MultiThreading & Multi-Core/MultiProcessor : How they are mapped?

2. What is the difference between MultiCore and MultiProcessor? [duplicate]

[RPi] ssh: Read from socket failed: Connection reset by peer

話說 raspbian 在 2017-02 的 image 以後預設把 sshd 關掉了, 要再打開除了使用 raspi-config 以外, 還可以在 command 打 sudo raspi-config nonint do_ssh 0

但如果已經開啟了, 可是從外部連線還是失敗呢？ 錯誤訊息如下

Read from socket failed: Connection reset by peer

根據 forum 討論, 做以下兩個步驟就可以了, 反正就是重新 gen RSA key

sudo rm /etc/ssh/ssh_host_*

sudo dpkg-reconfigure openssh-server

[新奇] 熱成像乳房攝影

感覺是打臉的

BREAST THERMOGRAPHY CRASH COURSE ~ THE ANSWERS YOU'VE BEEN SEARCHING FOR WITH IMAGES

[LoRa] 一些名詞和圖片

SNR

https://documentation.meraki.com/MR/WiFi_Basics_and_Best_Practices/Wireless_fundamentals%3A_Signal-to-Noise_Ratio_(SNR)__and_wireless_signal_strength

[RPi] QRCode

先安裝必要套件

$ sudo apt-get install -y python-dev python-opencv python-pip python-numpy libzbar-dev zbar-tools qrencode python-zbar
$ sudo pip install pathlib numpy Pillow

https://gist.github.com/mohankumargupta/243aeb6787123cc17f1c10338bd4a82f

[Tips] Copy-Paste in xfce4-terminal adds 0~ and 1~

怪問題, 複製貼上會在前面加上 0~ 最後面加上 1~

但開新的 terminal 就沒事, 不過這篇有提到, 留著備考吧

https://unix.stackexchange.com/questions/196098/copy-paste-in-xfce4-terminal-adds-0-and-1

[RPi] RTSP + H2.64

這篇用的是 lightweight 的 live555, 用起來還是有延遲...

https://panqiincs.github.io/2016/02/18/process-picamera-video-on-pc/