Linux
General command
chmod ugo+rwx directory1 --- 设置目录的所有人(u)、群组(g)以及其他人(o)以读（r ）、写(w)和执行(x)的权限
**Environment Variable**
export --- It is a bash shell BUILTINS commands, which means it is part of the shell. It marks an environment variable to be exported to child processes.
echo $SHELL_VARIABLE --- output the value of the variable if it has one
unset VARIABLE_NAME --- unset an environment variable
whoami cal date
Avoid redundant command !$ — return the path of the latest command !* — return all paths of the latest command !! — automatically replace the latest command
history | grep **** --- find certain historic commands
!**** --- **** is the id number of the command
To further reduce the code, u can write a func in the .bashsrc
cd & cd -
export CDPATH='~:/Desktop/working_directory' --- Add the common working directory to the shell variable
s
Files
diff filename1 filename2
zip file1.zip file1 --- 创建一个zip格式的压缩包
unzip temp.zip
ls -lsah --- -l long format | -s size | -a all files | -h human-readable output
wc filename --- tells you how many lines, words, and characters there are in a file
touch file.sh --- Create a newfile
# Open/read file
cat file.sh
less file.sh
vim file.sh
nano file.sh
# Vim:
0 Beginning of line
$ # End of line
gg # First line of file
G # Last line of file
dd # delete a line
:qa! # quit and abandon all changes
:q! # quit and overwrite/apply all changes
:wq # write and quit
Disk Space Storage
df -h --- Show Disk Space Usage in Human Readable Format
Network related
ifconfig --- check networking driver and usage
ping www.google.com --- checking network connection
nslookup www.google.com --- query Internet name servers as well as your local name server
Server: 128.146.48.7 --- local name server
Address: 128.146.48.7#53
Non-authoritative answer:
Name: www.google.com
Address: 142.251.35.164 --- IP address of google
Name: www.google.com
Address: 2607:f8b0:4006:807::2004
lspci --- find out linux wireless card chipset info
# Fun thing: Testing network speed
wget -O speedtest-cli https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py
chmod +x speedtest-cli
# Run it with
./speedtest.py
System related
passwd --- lets you change your password
Resource checking
lscpu --- Checking CPU
top --- display linux process, e.g. resource(cpu, mem...) usage
2023-05-03 Rviz2 in ArchLinux
------------------
Issues:
1. Can't start the rviz2
------------------
Solution：
1. Update the X11 |
take care of the graphic driver (Inter / Nvida)| http://wiki.ros.org/docker/Tutorials/Hardware%20Acceleration
xhost +local:root # adjust the permissions the X server host.
docker run \
--rm \ # Automatically removes the container when it exits.
--it \ # Starts an interactive terminal session.
--name \ # Assigns a name to the container (optional).
--net=host \ # Shares the host network namespace with the container, which is necessary for RViz2 to connect to the ROS network.
--volume=/tmp/.X11-unix:/tmp/.X11-unix \ # mounts the host machine's X11 socket directory into the Docker container, which allows the container to connect to the X11 display server
--env="QT_X11_NO_MITSHM=1" \
--env="DISPLAY=$DISPLAY" \ # sets the DISPLAY environment variable in the Docker container, which tells the graphical application where to display its output
--device=/dev/dri:/dev/dri \ # set the driver to Intel driver
docker_name
/bin/bash ` # Starts a Bash shell in the container.
Wifi logo is not found in ubuntu 20.04
About dual-boot with Windows and “fast-boot” enabled
If you have a dual-boot machine with a recent version of Windows and start seeing problems during initialization of the WiFi device when booting Linux, the problem could be due to the “fast startup” feature on Windows.
With this feature enabled, Windows don’t really shut down the entire system, but leaves things partially running so you can start the machine faster again. Try to disable this option, on Windows 10 it should be in “Control Panel→Hardware and Sound→Power Options→System Settings”. Select “Chooose what the power buttons do” to access the System Settings from the Power Options. Then disable the “Fast Startup” option in “Shutdown Settings”. This will cause Windows to fully shutdown and may solve the issue.
update the nvidia driver
install the tool for configuring the NVIDIA graphics driver
sudo apt-get install nvidia-settings
❌nvidia-settings won’t start: “Unable to find display on any available systems”
Because of running Wayland, we logout on the login screen you should have a gear in corner that allows you to switch to X11 currently that is the only way to control nvidia GPU that I know of.
❌nvidia-settings won’t start: “Unable to find display on any available systems”
sudo ubuntn-drivers devices
sudo ubuntn-drivers autoinstall
sudo prime-select nvidia # 切换nvidia显卡
sudo prime-select intel # 切换intel显卡
sudo prime-select query # 查看当前使用的显卡
for ref: https://blog.csdn.net/wf19930209/article/details/81877822
use autoinstall to upgrade the driver
sudo ubuntn-drivers autoinstall
#check if novueau is working
lsmod | grep nouveau
for ref:https://blog.csdn.net/u012386311/article/details/103402428?spm=1001.2101.3001.6650.1&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1-103402428-blog-82626538.pc_relevant_default&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1-103402428-blog-82626538.pc_relevant_default&utm_relevant_index=1
OpenCV setup in linux
# Install minimal prerequisites (Ubuntu 18.04 as reference)
sudo apt update && sudo apt install -y cmake g++ wget unzip ## (-y: automatic yes to prompts)g++:complier, wget:download the source code
# Download and unpack sources
wget -O opencv.zip https://github.com/opencv/opencv/archive/4.x.zip
# Create build directory
mkdir -p build && cd build
# Configure
cmake ../opencv-4.x
# Build
cmake --build .
Cmake
traditional method
mkdir build && cd build
cmake ..
make
make test
modern build procedure
mkdir -p build && cd build
cmake --build build -t test ## by passing the “test” target to the underlying build system. -t (--target before CMake 3.15) lets you select a target
Add Chinese input to the linux system
Check the following link out
https://www.dell.com/support/kbdoc/en-us/000181184/how-to-add-chinese-pinyin-input-to-xps-9310-laptops-that-ship-with-ubuntu-20-04-in-english