Useful

Reset user password on Ubuntu

here

To know the user, group of usb devices

ash@ROS:~$ ls -l /dev | grep USB and it will show something like crw-rw---- 1 root dialout 188, 0 Sep 2 14:11 ttyUSB0 where root is the user and dialout is the group
To add a particular user to a group sudo usermod -aG dialout ash. This will add user ash to the group dialout
To know the current user's group, run groups ash and it will produce ash : ash dialout video

Jekyll github pages using Docker

clone this github repo
cd jekyll-serve and docker build -t jekyll-serve .
Then go (cd) to the website folder containing the Gemfile. For example al-folio (has to be cloned locally) and it contains the Gemfile
docker run -p 4000:4000 -v $(pwd):/site jekyll-serve ## run it on the directory containing the Gemfile
Then the following appears at the end on the terminal

 Auto-regeneration: enabled for '/site'
    Server address: http://0.0.0.0:4000/
  Server running... press ctrl-c to stop.

Open http://0.0.0.0:4000/ in a browser to see the webpage

To kill processes

netstat -tulpn
kill -9 PID

Find a directory in linux

To find a directory called apt in / (root) file system, enter:

find / -type d -name "apt"
sudo find / -type d -name "apt"
find . -name thisfile.txt ### find a file

Pluginlib

Resource 1

Resource 2

namespace rtabmap_util
{

class ObstaclesDetection : public nodelet::Nodelet
{
  public:

  private:

};
PLUGINLIB_EXPORT_CLASS(rtabmap_util::ObstaclesDetection, nodelet::Nodelet);
}

<library path="lib/librtabmap_util_plugins"> 
<class name="rtabmap_util/obstacles_detection" 
         type="rtabmap_util::ObstaclesDetection" 
         base_class_type="nodelet::Nodelet">
    <description>
      This is my nodelet.
    </description>
  </class

Loading

#include <pluginlib/class_loader.h>
int main()
{
    pluginlib::ClassLoader<nodelet::Nodelet> poly_loader("nodelet", "nodelet::Nodelet");
    boost::shared_ptr<nodelet::Nodelet> obstacleDetection = poly_loader.createInstance("rtabmap_util/obstacles_detection");
}

Note: Passing parameters to the ObstacleDetection class is to be found out

Minimize windows on click here

gsettings set org.gnome.shell.extensions.dash-to-dock click-action 'minimize'

layaureo.sty not found and fontin error latex

sudo apt-get install texlive-lang-italian
Go to fontIn and download the TTF version at the bottom. Extract the zip and double click on each font to install it
sudo apt-get install texlive-fonts-extra
sudo apt-get install texlive-latex-extra
sudo apt install texlive-luatex
sudo apt-get install texlive-lang-french

Configure broken packages

sudo dpkg --configure -a

Errors were encountered while processing: /var/cache/apt/archives/python3-catkin-pkg-modules_0.5.2-1_all.deb

here

sudo dpkg -i --force-overwrite python3-catkin-pkg-modules_0.5.2-1_all.deb

sudo apt-get -f install

Install CMake

Now CMake developer team in Kitware Inc provides APT repositiory. It allows you to install latest CMake via apt-get.

If you are using a minimal Ubuntu image or a Docker image, you may need to install the following packages:

sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates gnupg software-properties-common wget

Obtain a copy of our signing key:

wget -qO - https://apt.kitware.com/keys/kitware-archive-latest.asc | sudo apt-key add -

Add the repository to your sources list and update.

For Ubuntu Bionic Beaver (18.04):

sudo apt-add-repository 'deb https://apt.kitware.com/ubuntu/ bionic main'
sudo apt-get update
sudo apt-get install cmake

Installing CLion to work with ROS (not to open from terminal every time)

remove existing installations
- sudo snap remove clion
- sudo find / -iname "*JetBrains*"
- will have to manually deleted all JetBrains folders
Download CLion and extract the clion.xxx. folder
sudo mv /path/to/clion.xxx /opt
cd /opt/clion.xxx/bin
./clion.sh ## set all the login stuff here for license and open a project
Once clion is opened, create a Desktop Entry. This can be done by Help-->FindAction and search for Desktop Entry. Close CLion
cd /usr/share/applications/
subl jetbrains-clion.desktop
Add bash -i -c to the Exec (Exec=bash -i -c "/opt/clion-2022.1.2/bin/clion.sh" %f)
Open CLion from anywhere and is good to go

Note: Clion once closed wont open again with the -i option with bash command in the Exec. So tried this answer and changed Exec=bash -c "source ~/.bashrc && /opt/clion-2022.1.3/bin/clion.sh %f" and it works now. Also, the following in .bashrc needs to be commented out

 case $- in
     *i*) ;;
       *) return;;
 esac

Increase swap size

Another resource

sudo swapoff /swapfile sudo rm /swapfile
sudo fallocate -l 15G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile or reboot

Python/python3 command not found

sudo apt-get install python/python3

Try python or python2 python2.7, python3, python 3.6. Depending upon the python version, one of these should work but a symlink is wrong or missing. sudo rm /usr/bin/python3 sudo ln -s /usr/bin/python3.6 /usr/bin/python3

Install Cuda using APT

Install latest Nvidia Drivers

ubuntu-drivers devices
sudo ubuntu-drivers autoinstall OR sudo apt install nvidia-driver-440
sudo reboot now

Change password via terminal

sudo passwd $whoami

Change look of terminal to parse and display git

parse_git_branch() {
     git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'
}
export PS1="[\[\033[01;31m\]\u\[\033[m\]@\[\033[01;34m\]\h\[\033[m\]] [\[\033[m\]\w\[\033[m\]]\[\033[33m\]\$(parse_git_branch)\[\033[00m\] \[\033[01m\]-\[\033[m\] "

For other colors of the prompt, export PS1="[\[\033[01;32m\]\u\[\033[m\]@\[\033[01;33m\]\h\[\033[m\]] [\[\033[m\]\w\[\033[m\]]\[\033[33m\]\$(parse_git_branch)\[\033[00m\] \[\033[01m\]-\[\033[m\] " # 01;32m for green and 01;33m for yellow

Name a terminal here

Comment out the following from .bashrc

case "$TERM" in
xterm*|rxvt*)
    # JEFFYEE REMOVED because it makes commands to title() not work
    #PS1="\[\e]0;${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]$PS1"
    ;;
*)
    ;;
esac

PROMPT_COMMAND='echo -ne "\033]0;SOME TITLE HERE\007"'

Fails to find Eigen

for example #include <Eigen/Core> throws error but can be rectified using #include <eigen3/Eigen/Core>
Another approach is
sudo ln -s /usr/include/eigen3/Eigen /usr/include/Eigen

CMTC error when catkin_make

sudo apt-get install libcgal-dev

Dual boot in Dell Computers

Problems encountered

Hard drive not being detected when trying to boot from the USB ubuntu disk and it tries to install it in the pendrive itself

** Procedure **

Press window+R key to and type in diskmgmt.msc. Shrink the drive to the required size for Ubuntu. This will be seen as unallocated
Follow this and change SATA to AHCI
Disable secure boot in BIOS
There is a chance that the boot will complain about mmx64.efi not found error. Just go to the installation disk, in \efi\boot\ rename grubx64.efi to mmx64.efi.
Follow this to set up your \swap, \home and \ (root) partitions

Note: Some Dell laptops goes to black screen when trying to connect to wifi during installation. Better connect via ethernet cable

Removing type 3 fonts for IEEE submissions

The error is caused by fonts used in Matplotlib plots. Check out this article. An example plot is available here

Nvidia GPU support for Tensorflow in Ubuntu 18.04 & 16.04

Update bashrc with

export LD_LIBRARY_PATH=/usr/local/cuda-10.2/lib64/bin:$LD_LIBRARY_PATH

Here, the folder cudaa-10.2 should be appropriate as there could be other cuda versions depending on the GPU that you have

Updating grup after nvidia driver installation AskUbuntu

sudo nano /etc/default/grub and add the parameter nvidia-drm.modeset=1 to the line GRUB_CMDLINE_LINUX_DEFAULT. Save the change and run sudo update-grub. Restart

AnyDesk fails to show login screen after installing nvidia drivers

Error:remote server display not supported e.g Wayland.

Solution:

Go to /etc/gdm3/custom.conf file and change:

[daemon]
    # Enabling automatic login
    AutomaticLoginEnable=true
    AutomaticLogin=$USERNAME

To enable/disable ubuntu from hibernating, sleep etc.

sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target # to disable hibernating

sudo systemctl unmask sleep.target suspend.target hibernate.target hybrid-sleep.target # to enable hibernating

Adding folders to python path

import sys
sys.path.append('/path/to/application/app/folder')

Video recording (for presentations) and editing in Ubuntu

sudo apt-get install vokoscreen for audio + webcam recording
sudo apt-get install kdenlive for video editing like windows movie maker

To list all available gym environments

Details here

import gym
gym.envs.registry.all()

To print strings and numbers using % sign

d, s = 20, 'Ash'
print('%s is my name and my age is %.2d' % (s, d))
Out: Ash is my name and my age is 20
print('%s is my name and my age is %.4d' % (s, d))
Out: Ash is my name and my age is 0020

To get control of gnome settings

sudo apt install gnome-tweak-tool This will show up as Tweaks in the Menu

Install MuJoCo Youtube

Get the license mjkey.txt as detailed in here
Download MuJoCo, extract and place it in the desired folder
Update the ~/.bashrc as shown below by pointing to the bin folder

export LD_LIBRARY_PATH=/home/ash/softwares/mujoco200_linux/bin:$LD_LIBRARY_PATH

export PATH=$LD_LIBRARY_PATH:$PATH

Inside bin folder, run ./simulate ../model/humanoid.xml to test the installation

Install mujoco-py

Unzip the downloaded mujoco directory into ~/.mujoco/mujoco200, and place your license key (the mjkey.txt file from your email) at ~/.mujoco/mjkey.txt.
Update ~/.bashrc as follows (set bin folder using export)

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/ash/.mujoco/mujoco200/bin

pip3 install -U 'mujoco-py<2.1,>=2.0'

Note: If the above doesnt work, it's best to clone the mujoco-py repo and do a pip install -e . to install dependencies.

If patchelf error comes

sudo add-apt-repository ppa:jamesh/snap-support sudo apt-get update sudo apt install patchelf

sudo apt install libosmesa6-dev libgl1-mesa-glx libglfw3

If you installed above libraries and you still see an error that -lGL cannot be found, most likely you need to create the symbolic link directly:

sudo ln -s /usr/lib/x86_64-linux-gnu/libGL.so.1 /usr/lib/x86_64-linux-gnu/libGL.so

If GLEW initialization error comes. Install libglew-dev using synaptic package manager and add the following to bashrc

export LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libGLEW.so

Install Pinnochio & examples

Add robotpkg repo. Note: Replace the appropriate version of Ubuntu in the following line by lsb_release -c

sudo sh -c "echo 'deb [arch=amd64] http://robotpkg.openrobots.org/packages/debian/pub bionic robotpkg' >> /etc/apt/sources.list.d/robotpkg.list"
curl http://robotpkg.openrobots.org/packages/debian/robotpkg.key | sudo apt-key add -
sudo apt-get update
sudo apt-get install robotpkg-py36-pinocchio
Configure environment variables by adding the following in .bashrc

export PATH=/opt/openrobots/bin:$PATH
export PKG_CONFIG_PATH=/opt/openrobots/lib/pkgconfig:$PKG_CONFIG_PATH
export LD_LIBRARY_PATH=/opt/openrobots/lib:$LD_LIBRARY_PATH
export PYTHONPATH=/opt/openrobots/lib/python2.7/site-packages:$PYTHONPATH

Analytical Derivatives of Rigid Body Dynamics Algorithms

A very good example

Time derivative of Jacobian

Install virtualenv

sudo apt install python3-pip
pip3 install virtualenv
python3 -m venv /path/venv_name
source /path/venv_name/bin/activate

Adding/Removing virtual env in jupyter notebook

Remove

jupyter kernalspec list
jupyter kernelspec uninstall unwanted-kernel-name

Add

Activate virtual environment source path_to_env/bin/activate.
pip install jupyter notebook
pip install --user ipykernel
python -m ipykernel install --user --name=env_name

CUPS not showing username and password

Edit /etc/cups/cupsd.conf

Change:

<Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default CUPS-Get-Devices>
AuthType Default
Require user @SYSTEM
Order deny,allow
</Limit>

To:
<Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default CUPS-Get-Devices>
AuthType None
Order deny,allow
</Limit>

sudo service cups restart or restart

New document on right click menu here

touch ~/Templates/"Untitled Document"

“UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure.”

solution: sudo apt-get install python3-tk

To have Terminator on the right click menu check here

sudo add-apt-repository ppa:daniel-marynicz/filemanager-actions sudo apt-get install filemanager-actions-nautilus-extension Run fma-config-tool in the terminal. In the FileManager-Action Configuration Tool, go to File-->New Action, In Action tab, add context label as Open in terminator, check box 'display item on location context menu'. In command tab, add path as /usr/bin/terminator or find out path of programs by typing which terminator in terminal. Add Parameter --workidng-directory=%d/%b

solution: inotify_watch failed

echo fs.inotify.max_user_watches=65536 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p

Modify setup.py to make Mass/Coriolis matrices for import

Activate the virtual env by source path/to/venv/bin/activate. The MassMatrix folder has several files starting with filename wrapper. Take the setup.py outside MassMatrix folder and add path as shown below

af = '/home/ash/Ash/model_predictive_control/src/MassMatrix/'
ext_mods = [Extension(
    af+'wrapper_module_0', [af+'wrapper_module_0.pyx', af+'wrapped_code_0.c'],
 ...............
..............

Then run python setup.py install to make the wrapper_module_0.pyx available for import. The import can be carried out as from MassMatrix.wrapper_module_0 import autofunc_c as MassMatrix

Launch jupyter notebook in preferred browser

jupyter notebook --generate-config

c.NotebookApp.browser = '/usr/bin/google-chrome'

You'll find the path for example by typing which firefox

Fix for 'error while loading shared libraries: cannot open shared object file: No such file or directory'

Find where the library is placed if you don't know it.

sudo find / -name the_name_of_the_file.so

Check for the existence of the dynamic library path environment variable(LD_LIBRARY_PATH)

echo $LD_LIBRARY_PATH

if there is nothing to be displayed, add a default path value (or not if you wish to)

LD_LIBRARY_PATH=/usr/local/lib

Add the desire path in the .bashrc

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:path_obtained_from_find

Drake

Binary Installation

Homepage

curl -o drake.tar.gz https://drake-packages.csail.mit.edu/drake/continuous/drake-latest-bionic.tar.gz

sudo tar -xvzf drake.tar.gz -C /opt

sudo /opt/drake/share/drake/setup/install_prereqs

export PYTHONPATH=/opt/drake/lib/python2.7/site-packages:${PYTHONPATH}

Underactuated

git clone https://github.com/RussTedrake/underactuated.git

sudo underactuated/scripts/setup/ubuntu/18.04/install_prereqs

export PYTHONPATH=`pwd`/underactuated/src:${PYTHONPATH} # change 'pwd' to the appropriate direction to which underactuated is cloned

python3 -c 'import pydrake; print(pydrake.__file__)

Docker

Installation Homepages

cd Downloads/drake_docker_utility_scripts

./docker_run_notebook.sh drake-20190129 ./set_1_code # To open the jupyter connection

Open a browser and go to http://127.0.0.1:8080/. Use password mit6832.

Inside ~/Downloads/drake_docker_utility_scripts, run ./docker_run_bash_linux.sh drake-20190129 . to get the terminal access

Fix to pycharm fail to import cv2

File->Settings->Project Interpreter and then '+' button 'opencv-python' --> Install package

Extracting rar files Ubuntu

sudo apt-get install unrar

unrar x filename.rar

Anaconda Installation

Download

Installation Instructions

Set (base) in terminal to False

After installing anaconda, by default the terminal appears to have (base) user@username: . This would install all python packages to the anaconda installation directory. To prevent this, run the following conda config --set auto_activate_base False

Texlive Texworks and Texstudio installation

Texlive TexStudio

sudo add-apt-repository ppa:jonathonf/texlive-2019
sudo apt-get install texlive

update python libraries to search for

sudo update-alternatives --config python3

Install Rigid body dynamics library

(urdf model loading not working, 21/05/2019) Pre-requisite:

Download Eigen3 linear algebra library from http://eigen.tuxfamily.org and extract it
cd into the above folder. mkdir build cd build cmake ../ make install
git clone https://github.com/ros/urdfdom_headers.git mkdir build cd build cmake -D CMAKE_BUILD_TYPE=Release ../ sudo make install
git clone https://github.com/ros/urdfdom.git mkdir build cd build cmake -D CMAKE_BUILD_TYPE=Release ../ sudo make install

In the rbdl\CmakeLists.txt, change OPTION (RBDL_BUILD_PYTHON_WRAPPER "Build experimental python wrapper" ON) OPTION (RBDL_BUILD_ADDON_URDFREADER "Build the (experimental) urdf reader" ON)

mkdir build cd build/ sudo cmake -std=c++11 -D CMAKE_BUILD_TYPE=Release -D RBDL_BUILD_PYTHON_WRAPPER=ON RBDL_BUILD_ADDON_URDFREADER=ON ../ ../ sudo make -j4 sudo make install The above will create a setup.py file in /path/rbdl/python/python. I copied the file to /path/rbdl/python and ran sudo ./setup.py install

Testing:

In the terminal, type python to go to python prompt. >>> import rbdl

To get the version of package in venv

(venv) test@test:~/Ash/robot_arm_RL$ pip list | grep tensorflow # in pycharm terminal

General Notes

pip install --upgrade scipy=1.2.0 # to have scipy.interpolate (not available in 0.17.0)
while running catkin_make, warehouseConfig.cmake error due to files missing in MoveIt. Reinstall MoveIt from here

python pip installation/uninstall

sudo apt install python3-pip

sudo python -m pip uninstall pip && sudo apt install python-pip --reinstall

sudo apt-get remove python-pip # to remove pip

pip install pip==9.0.1 # to install specific pip version

Note: Do not upgrade pip using pip install upgrade --pip as it throws some error ImportError: cannot import name main as of 18/03/2019

Note: The above import error no longer occurs after running hash -d pip. (12/06/2019)

Python control system installation (matplotlib, numpy and scipy are essential)

sudo apt-get install python-numpy python-scipy python-matplotlib

pip install slycot

pip install control

If the above slycot installation doesnt work, follow

pip install scikit-build

sudo apt-get install gfortran liblapack-dev

git clone https://github.com/python-control/Slycot.git slycot

cd slycot

sudo python setup.py install

Install sublime text

wget -qO - https://download.sublimetext.com/sublimehq-pub.gpg | sudo apt-key add -
echo "deb https://download.sublimetext.com/ apt/stable/" | sudo tee /etc/apt/sources.list.d/sublime-text.list
sudo apt-get update
sudo apt-get install sublime-text

Uninstall sublime:

sudo apt-get remove sublime-text && sudo apt-get autoremove

General

If you have a CMakeLists.txt, cd to the directory and use 'cmake CMakeLists.txt' in terminal first and then 'make' to get the executable file. Note that the CMakeLists.txt should contain a file_name.cpp whose contents are to be there inside the same folder containing CMakeLists.txt as a separate file
Inverse kinematics in moveit is computed using the "compute_ik" service call. The compute_ik is defined as IK_SERVICE_NAME in the file capability_names.h (/src/moveit/moveit_ros/move_group/include/moveit/move_group) and it calls the kinematics_service_capability.cpp(/src/moveit/moveit_ros/move_group/src/default_capabilities) which has the function definition for IK.

How to use pcl_viewer from PCL

pcl_viewer -multiview 1 chef.pcd

How to kill non-responding program using terminal

ps ax |grep controller.py

output: 16768 pts/17 Sl+ 0:00 python controller.py

kill -9 16768

SSH connection to franka2

Install ssh server from here nc -v -w 1 10.5.32.5 -z 22 # To check if ssh is installed and 22 is the port number ssh [email protected]

give the password: p_ _ g _ _n

to close type 'exit' or press ctrl+D

copy files from remote computer to host

Terminal on remote shows ujjar@headlight
On the host terminal, do the following
scp [email protected]:/home/ujjar/telesto_test/pcds_.zip /home/ash/Ash # to copy file
scp -r [email protected]:/home/ujjar/telesto_test/ /home/ash/Ash # to copy folder

To crop image via terminal

convert figure.png -trim +repage a.png

To convert one video format to other

ffmpeg -i input.wmv -s size output.mp4 ffmpeg -i fwd_kin.mp4 -qscale 0 -vf scale=-1:760 fwd_kin.wmv # to preserve quality

To reduce video size

ffmpeg -i input.mp4 -vcodec libx265 -crf 28 output.mp4 # libx265 (H.265) is better than libx264 (H.264) but it wont play in browser
ffmpeg -i input.mp4 -vcodec libx264 -crf 35 output.mp4

(size could be qcif 176x144, cif 352x288, 4cif 704x576, 16cif i408x1152, qqvga 160x120, qvga 320x240, vga 640x480, svga 800x600, xga 1024x768, uxga 1600x1200, qxga 2048x1536, sxga 1280x1024, qsxga 2560x2048, hsxga 5120x4096, wvga 852x480, wxga 1366x768, wsxga 1600x1024, wuxga 1920x1200, woxga 2560x1600, wqsxga 3200x2048, wquxga 3840x2400 )

To crop and join mp3s using ffmpeg

ffmpeg -i input_name.mp3 -ss 00:01:40 -to 00:02:20 -c copy output_name.mp3 # crop from 1 min 40 sec to 2 min 20 sec

ffmpeg -i "concat:input_1.mp3|input2.mp3" -acodec copy output.mp3

To crop in time of videos

ffmpeg -i source.mp4 -ss 00:00:00 -t 00:00:00 -vcodec copy -acodec copy splice.wmv

This will take source.mp4 and, using the same audio and video codecs and not degrading quality, take -t time after -ss start time and output as splice.wmv. Also, in some distributions, ffmpeg has been replaced with avconv. To run this install

sudo apt-get install libav-tools

Example:

avconv -i originalFile.wmv -ss 00:00:00 -t 00:00:10 -vcodec copy -acodec copy croppedFile.mp4

A similar thing can be done using VLC media player and the detailed instructions are here

To convert videos to images

ffmpeg -i DSC_0183.MOV -qscale:v 2 -s -s 1920x1080 thumb%04d.jpg -hide_banner # -qscale to control quality of images

rename 's/\d+/sprintf("%04d", $&)/e' *.jpg # to rename continuously to 4 digits (%4d 0001, 0002 ...)

To convert images to videos

ffmpeg -framerate 30 -pattern_type glob -i '*.jpg' -c:v libx264 -r 30 -pix_fmt yuv420p out.mp4

To convert videos to gif

ffmpeg -ss 18 -t 47 -i dmp.wmv -vf scale=320:-1 -r 10 -f image2pipe -vcodec ppm - | convert -delay 5 -loop 0 - gif:- | convert -layers Optimize - dmp1.gif

-ss 18 skips the first 18 seconds

-t 47 for 47 seconds

Change the video aspect ratio

ffmpeg -i input.mp4 -vf scale=400:400 output.mp4 -hide_banner

To stack videos horizontal or vertical

ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex vstack output.mp4 for vertical stack

ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex hstack output.mp4 for horizontal stack

ffmpeg -i sample.avi -q:a 0 -map a sample.mp3 To extract audio from video

To have meld compare on right click menu

sudo apt-get install -y meld ## for ubuntu 20.04

sudo apt-get install nautilus-compare ## for ubuntu 18.04

nautilus -q