Santhosh Dhaipule Chandrakanth's questions

I wanted to read a pdf on my laptop Lubuntu which uses xrandr

Can do

xrandr -o left
xrandr -o right
xrandr -o normal

which works

Found How to Rotate Display in Ubuntu, Linux installed sudo apt install arandr

In both cases when I switch from Landscape to portrait mode

My cursor directions get reversed

to move from top - bottom I have to move my fingers from right - left

to move from right - left I have to move my fingers from top - bottom

How do I fix this?

I want the cursor to operate properly in both Landscape to portrait mode

I updated my system to Ubuntu 20.04

I already had Python 3.6.7 running with virtualenv and virtualenvwrapper for my python virtual environment.

After the update

I am able to check get the list of virtual environments those I have already created, but when I tried creating a new virtual environment mkvirtualenv -p python newenv

I get this message

Traceback (most recent call last):
  File "/home/abcd/.local/bin/virtualenv", line 7, in <module>
    from virtualenv import main
ImportError: cannot import name 'main' from 'virtualenv' (/usr/lib/python3/dist-packages/virtualenv/__init__.py)

Then I checked the python version after update it was Python 3.8.5

I checked for main inside virtualenv that the Python 3.8.5

Python 3.8.5 (default, Jan 27 2021, 15:41:15) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from virtualenv import main
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'main' from 'virtualenv' (/usr/lib/python3/dist-packages/virtualenv/__init__.py)
>>> 

I tried installing virtualenv and virtualwrapper for Python 3.8.5

python -m pip install virtualenv virtualenvwrapper

since my default Python version is 3.8.5 after the update

even after installing I get the same message ImportError: cannot import name 'main' from 'virtualenv'

I found this post Problem with creating Python 3.6 virtual environment on Ubuntu 20.04

Installed Python 3.6.7 as suggested the most popular answer

cd opt
sudo wget https://www.python.org/ftp/python/3.6.7/Python-3.6.7.tgz
sudo tar -xvf Python-3.6.7.tgz
cd Python-3.6.7

make clean

sudo ./configure

sudo make
sudo make install

updated my bashrc

export VIRTUALENVWRAPPER_PYTHON=/usr/local/bin/python3
export WORKON_HOME=$HOME/.virtualenvs
export VIRTUALENVWRAPPER_VIRTUALENV=/home/abcd/.local/bin/virtualenv

# Virtual Environment Wrapper
source /home/abcd/.local/bin/virtualenvwrapper.sh

For VIRTUALENVWRAPPER_PYTHON

which python3
/usr/local/bin/python3

For VIRTUALENVWRAPPER_VIRTUALENV

sudo find / -name "virtualenv"
/home/abcd/.local/bin/virtualenv

For virtualenvwrapper.sh

sudo find / -name "virtualenvwrapper.sh"
/home/abcd/.local/bin/virtualenvwrapper.sh

source ~/.bashrc

Python3 -V displays Python 3.6.7

Python -V displays Python 3.8.5

Installed virtualenv and virtualenvwrapper for Python 3.6.7, using Python3 -m pip install virtualenv virtualenvwrapper

Now I tried creating a virtualenv using Python 3.6.7

mkvirtualenv -p python3 newenv

I get back the same message

Traceback (most recent call last):
  File "/home/abcd/.local/bin/virtualenv", line 7, in <module>
    from virtualenv import main
ImportError: cannot import name 'main' from 'virtualenv' (/usr/lib/python3/dist-packages/virtualenv/__init__.py)

When I went inside the Python 3.6.7 and Python 3.8.5 check for from virtualenv import main

Python 3.8.5 (default, Jan 27 2021, 15:41:15) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from virtualenv import main
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'main' from 'virtualenv' (/usr/lib/python3/dist-packages/virtualenv/__init__.py)
>>> 

Python 3.6.7 (default, May 26 2021, 09:24:09) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from virtualenv import main
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name 'main'
>>> 

Whats is the solution, here?

I wanted to remove tensorRT 7

/var/nv-tensorrt-repo-cuda10.2-trt7.0.0.11-ga-20191216

which use to getting updated when I was installing tensorRT 6

sudo apt-get update

so I removed sudo rm -rf /var/nv-tensorrt-repo-cuda10.2-trt7.0.0.11-ga-20191216

then again when I tried to use sudo apt-get update

I get this error message and update stops

Reading package lists... Done                                      
E: The repository 'file:/var/nv-tensorrt-repo-cuda10.2-trt7.0.0.11-ga-20191216  Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

sudo apt-get clean doesn't work

How to I reset the sudo apt-get update so that it will not pop this error?

source to install TensorRT

System info

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.3 LTS
Release:    18.04
Codename:   bionic

Tried building kde connect from source

after i run

sudo apt-get build-dep kdeconnect

i get

Reading package lists... Done
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 builddeps:kdeconnect : Depends: libqca2-plugin-ossl but it is not installable
E: Unable to correct problems, you have held broken packages.

Tried installing from

1. How to Use KDE Connect with MATE on Ubuntu and Debian
2. Install KDE Connect in Ubuntu 18.04
3. How to install KDE connect in ubuntu 17.04?

All the mentioned unable to launch kde connect indicator or kde connect

Please guide

New to linux and ubuntu. I have shared my laptop info. Boot up time is sooooo slowwwww. Even lauch of firefox takes long time.

Can anyone help me figure out how to optimize my system?

Using Lubuntu (Ubuntu Version)

Command

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.2 LTS
Release:    18.04
Codename:   bionic

Command

$ sudo lshw -short
H/W path         Device     Class          Description
======================================================
                            system         Aspire A515-51G (0000000000000000)
/0                          bus            Charmander_KL
/0/0                        memory         128KiB BIOS
/0/4                        processor      Intel(R) Core(TM) i5-8250U CPU @ 1.60
/0/4/5                      memory         256KiB L1 cache
/0/4/6                      memory         1MiB L2 cache
/0/4/7                      memory         6MiB L3 cache
/0/d                        memory         4GiB System Memory
/0/d/0                      memory         4GiB SODIMM DDR4 Synchronous Unbuffer
/0/d/1                      memory         [empty]
/0/100                      bridge         Xeon E3-1200 v6/7th Gen Core Processo
/0/100/2                    display        UHD Graphics 620
/0/100/14                   bus            Sunrise Point-LP USB 3.0 xHCI Control
/0/100/14/0      usb1       bus            xHCI Host Controller
/0/100/14/0/5               communication  Bluetooth wireless interface
/0/100/14/0/7               multimedia     HD WebCam
/0/100/14/1      usb2       bus            xHCI Host Controller
/0/100/15                   generic        Sunrise Point-LP Serial IO I2C Contro
/0/100/15.1                 generic        Sunrise Point-LP Serial IO I2C Contro
/0/100/16                   communication  Sunrise Point-LP CSME HECI #1
/0/100/17                   storage        Sunrise Point-LP SATA Controller [AHC
/0/100/1c                   bridge         Sunrise Point-LP PCI Express Root Por
/0/100/1c/0                 display        GP108M [GeForce MX150]
/0/100/1c.4                 bridge         Sunrise Point-LP PCI Express Root Por
/0/100/1c.4/0               generic        RTL8411B PCI Express Card Reader
/0/100/1c.4/0.1  enp2s0f1   network        RTL8111/8168/8411 PCI Express Gigabit
/0/100/1c.5                 bridge         Sunrise Point-LP PCI Express Root Por
/0/100/1c.5/0    wlp3s0     network        Dual Band Wireless-AC 3168NGW [Stone 
/0/100/1f                   bridge         Intel(R) 100 Series Chipset Family LP
/0/100/1f.2                 memory         Memory controller
/0/100/1f.3                 multimedia     Sunrise Point-LP HD Audio
/0/100/1f.4                 bus            Sunrise Point-LP SMBus
/0/1             scsi0      storage        
/0/1/0.0.0       /dev/sda   disk           1TB WDC WD10SPZX-21Z
/0/1/0.0.0/1     /dev/sda1  volume         927GiB EXT4 volume
/0/1/0.0.0/2     /dev/sda2  volume         3970MiB Extended partition
/0/1/0.0.0/2/5   /dev/sda5  volume         3970MiB Linux swap volume

Used this command

$ systemd-analyze critical-chain
The time after the unit is active or started is printed after the "@" character.
The time the unit takes to start is printed after the "+" character.

graphical.target @1min 6.870s
└─multi-user.target @1min 6.870s
  └─kerneloops.service @1min 6.842s +26ms
    └─network-online.target @1min 6.836s
      └─NetworkManager-wait-online.service @58.305s +8.529s
        └─NetworkManager.service @48.794s +9.507s
          └─dbus.service @48.775s
            └─basic.target @48.690s
              └─sockets.target @48.690s
                └─snapd.socket @48.620s +69ms
                  └─sysinit.target @48.618s
                    └─systemd-timesyncd.service @48.458s +159ms
                      └─systemd-tmpfiles-setup.service @47.215s +1.185s
                        └─systemd-journal-flush.service @5.764s +41.448s
                          └─systemd-remount-fs.service @4.325s +1.438s
                            └─systemd-journald.socket @4.229s
                              └─system.slice @4.229s
                                └─-.slice @4.170s

Saw this post Can we talk about the boot time on Ubuntu 18.04?

Ran

$ systemd-analyze time
Startup finished in 4.907s (kernel) + 7min 8.181s (userspace) = 7min 13.089s
graphical.target reached after 1min 6.870s in userspace

Ran

$ service --status-all | grep '+' | wc -l
27

I would like to see what's going on my Linux desktop screen on my android phone. When I'm away from my laptop. I mean reverse of screen mirroring android device on a Linux desktop.