Learning objectives: linux learning record

21.9.25

1. Terminal copy and paste shortcut key

: Copy: Ctrl+Shift+C paste: Ctrl+Shift+V
Daily operation Ctrl+C | V

Ubuntu 16.04 opens multiple terminals, one terminal has multiple small windows, and enlarges and shrinks the terminal font

Ctrl + Shift + T, one terminal opens multiple small terminals

Ctrl + Alt + T open multiple terminals

Ctrl + Shift + = enlarge terminal font

Ctrl + - reduce the terminal font - is a minus sign

2. View Linux version

1 view the installed version information file through the cat command
The cat command is used to connect files and print to standard output devices
Refer to: cat command
Command: cat /proc/version
2. View system related information through the uname command uname -a
Refer to: uname command
Command: uname -a

3.Python version switching

update-alternatives --list python
update-alternatives --config python
update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1((followed by label)
update-alternatives --install /usr/bin/python python /usr/bin/python3.5 2

vim file save exit

vi w save the file without exiting
: w file save the changes to file separately, do not exit vi
:w! Forced save, do not push vi
vi wq save file and exit
:wq! Force save file and exit vi
: q quit vi without saving the file
:q! Force exit without saving file vi
:e! Discard all changes and edit the command history from the last saved file

ros create project

mkdir catkin_ws/src
cd get into src
catkin_make
$ cd ~/catkin_ws
$ rosdep install --from-paths src --ignore-src --rosdistro=kinetic -y
$ catkin_make
 source ~/catkin_ws/devel/setup.bash   (catkin_ws/src Proceed under)
$ echo "source ~/catkin_ws/devel/setup.bash" >> ~/.bashrc (Under the terminal,Ensure that there is an environment every time)

Rosdep install -- from paths SRC -- ignore SRC -- rosdistro = kinetic - y error

rosdep install --from-paths src --ignore-src --rosdistro=kinetic -y
ERROR: the following packages/stacks could not have their rosdep keys resolved
to system dependencies:
robot_sim_demo: Cannot locate rosdep definition for [yocs_cmd_vel_mux]
navigation_sim_demo: Cannot locate rosdep definition for [dwa_local_planner]
slam_sim_demo: Cannot locate rosdep definition for [hector_mapping]

solve

sudo apt-get install ros-kinetic-yocs-cmd-vel-mux ros-kinetic-dwa-local-planner ros-kinetic-hector-mapping  (stay root Process under, not root (unsuccessful)

cd ~/catkin_ws/src
$ git clone https://github.com/DroidAITech/ROS-Academy-for-Beginners.git

Dependencies required to install the teaching package

$ cd ~/catkin_ws
$ rosdep install --from-paths src --ignore-src --rosdistro=kinetic -y

Compile and refresh the environment

$ catkin_make
$ source ~/catkin_ws/devel/setup.bash(Just start the simulation source (click)
echo source ~/catkin_ws/devel/setup.bash >> ~/.bashrc (Let each terminal run the simulation)

function

roslaunch robot_sim_demo robot_spawn.launch ;Running simulation
rosnode list ；Print node node
rosnode info /Node; View node information function
rosrun robot_sim_demo robot_keyboard_teleop.py : Keyboard controlled robot
rosrun image_view ；Then it's not the Enter key, but tap key
rosrun image_view image_view image:=/camera/rgb/image_raw ;Control camera

Welcome to the Markdown editor

Hello! This is the welcome page displayed by the Markdown editor for the first time. If you want to learn how to use the Markdown editor, you can read this article carefully to understand the basic grammar of Markdown.

New changes

We have expanded some functions and syntax support for the Markdown editor. In addition to the standard Markdown editor functions, we have added the following new functions to help you blog with it:

1. The new interface design will bring a new writing experience;
2. Set your favorite code highlight style in the creation center, and Markdown will display the selected highlight style of code slice display;
3. The picture drag function is added. You can drag local pictures directly to the editing area for direct display;
4. New KaTeX mathematical formula syntax;
5. Added mermaid syntax supporting Gantt chart 1 Function;
6. The function of multi screen editing Markdown article is added;
7. Functions such as focus writing mode, preview mode, concise writing mode and synchronous wheel setting in left and right areas are added. The function button is located between the editing area and preview area;
8. Added check list function.

Function shortcut

Undo: Ctrl/Command + Z
Redo: Ctrl/Command + Y
Bold: Ctrl/Command + B
Italic: Ctrl/Command + I
Title: Ctrl/Command + Shift + H
Unordered list: Ctrl/Command + Shift + U
Ordered list: Ctrl/Command + Shift + O
Checklist: Ctrl/Command + Shift + C
Insert code: Ctrl/Command + Shift + K
Insert link: Ctrl/Command + Shift + L
Insert picture: Ctrl/Command + Shift + G
Find: Ctrl/Command + F
Replace: Ctrl/Command + G

1. mermaid syntax description ↩︎