cdahms's questions

Suppose my screen looks like this:

Is there a setting I can change to map all of the active area of a Wacom tablet to only the area on the screen that I've draw around in red, which in this case is the drawable area of a Google Jamboard?

I've checked under Settings -> Wacom Tablet, and also checked the Ubuntu man page for xsetwacom https://manpages.ubuntu.com/manpages/trusty/man1/xsetwacom.1.html and I don't see such a setting.

Apparently the Windows version of the Wacom software has this functionality in it:
https://developer-support.wacom.com/hc/en-us/articles/9354476441623-How-can-I-map-my-Intuos-tablet-to-part-of-my-PC-monitor-

But that does not help much since I'm using Ubunu. I'm using either Ubuntu 20.04 or 22.04 if that matters. Any suggestions?

Is there a way to get the value pi on the Ubuntu Calculator? I hoped this would work but as you can see it does not:

Of course I can type in 3.14159 and in > 99% of cases that will be accurate enough, but if there is an actual way to get pi that would be great.

I'm trying to follow this tutorial from 2018:

http://www.codebind.com/linux-tutorials/install-opengl-ubuntu-linux/

I'm under the impression that things must have changed with Ubuntu and configuring OpenGL since these instructions no longer work. In case the article disappears at some point I'll re-iterate all the steps here:

Ubuntu 20.04 install

Verify NVIDIA GPU is properly recognized by Ubuntu, install and configure CUDA (verified works with PyTorch)

Now on to the OpenGL specific stuff:

sudo apt-get install libglu1-mesa-dev freeglut3-dev mesa-common-dev

enter this program in gedit, save it as main.cpp:

#include <GL/glut.h>

void displayMe(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_POLYGON);
    glVertex3f(0.5, 0.0, 0.5);
    glVertex3f(0.5, 0.0, 0.0);
    glVertex3f(0.0, 0.5, 0.0);
    glVertex3f(0.0, 0.0, 0.5);
    glEnd();
    glFlush();
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE);
    glutInitWindowSize(400, 300);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Hello world!");
    glutDisplayFunc(displayMe);
    glutMainLoop();
    return 0;
}

Compile:

gcc main.cpp -o firstOpenGlApp -lglut -lGLU -lG

Here is the resulting output:

$ gcc main.cpp -o firstOpenGlApp -lglut -lGLU -lG
/usr/bin/ld: cannot find -lG
collect2: error: ld returned 1 exit status

Did something pertaining to configuring OpenGL change since this tutorial was written? What am I missing?

I have a machine with a 2 TB M.2 HD dual booted with Ubuntu 20.04 and 18.04 (still need 18.04 for legacy reasons, please don't ask for the details :).

I just did an update to 20.04 and now 18.04 won't boot without choosing a special option. Here is my usual grub screen upon boot:

If I choose Ubuntu 18.04 I get this:

If instead at the main boot menu I choose Advanced options for Ubutnu 18.04.5 LTS (18.04) (on /dev/nvme0n1p2) I get this:

If I choose any of these non-recovery mode options everything boots and works normally.

What I don't understand is why is the usual boot option looking for kernel version ending in 70? It's not there anymore! How can I make it look for one of the kernel versions that is there?

I did some more poking around, when I ls the contents of /boot I get:

$ ls -l
total 169176
-rw-r--r-- 1 root root   237757 Apr 16 07:44 config-5.4.0-73-generic
-rw-r--r-- 1 root root   237757 Jul 13 10:52 config-5.4.0-80-generic
-rw-r--r-- 1 root root   237757 Jul 23 05:56 config-5.4.0-81-generic
drwx------ 3 root root     4096 Dec 31  1969 efi
drwxr-xr-x 6 root root     4096 Aug 19 11:17 grub
-rw-r--r-- 1 root root 43261536 Jul 22 09:33 initrd.img-5.4.0-73-generic
-rw-r--r-- 1 root root 43267722 Jul 23 10:31 initrd.img-5.4.0-80-generic
-rw-r--r-- 1 root root 43266831 Aug 17 11:26 initrd.img-5.4.0-81-generic
-rw-r--r-- 1 root root   182704 Jan 28  2016 memtest86+.bin
-rw-r--r-- 1 root root   184380 Jan 28  2016 memtest86+.elf
-rw-r--r-- 1 root root   184840 Jan 28  2016 memtest86+_multiboot.bin
-rw------- 1 root root  4586616 Apr 16 07:44 System.map-5.4.0-73-generic
-rw------- 1 root root  4587397 Jul 13 10:52 System.map-5.4.0-80-generic
-rw------- 1 root root  4587874 Jul 23 05:56 System.map-5.4.0-81-generic
-rw------- 1 root root  9449728 Apr 16 07:44 vmlinuz-5.4.0-73-generic
-rw------- 1 root root  9453824 Jul 13 11:28 vmlinuz-5.4.0-80-generic
-rw------- 1 root root  9457920 Jul 23 05:59 vmlinuz-5.4.0-81-generic

So once again vmlinuz ending in 73, 80, and 81 are present but not the 70 that grub seems to be looking for. I also checked /boot/grub/grub.conf and it also has entries for 73, 80, and 81 but not 70! Where is grub getting 70 from?

Based on some other posts I also tried pressing c from the grub main menu to do a terminal session, I found the following information but I'm not sure what do to, sorry this pic is a bit blurry:

I'm not sure how to enter a command here to resolve this if that is possible.

One more thing I should mention is after doing the advanced boot option to get back into Ubuntu 18.04 I tried:

sudo apt-get update
sudo apt-get upgrade

and

sudo update-grub

hoping that these would resolve the concern but they did not. Suggestions ??

-- Response to @heynnema --

here is my terminal output from your suggested command:

$ sudo update-initramfs -c -k 5.4.0-81-generic
[sudo] password for cdahms: 
update-initramfs: Generating /boot/initrd.img-5.4.0-81-generic
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8125a-3.fw for module r8169
W: Possible missing firmware /lib/firmware/rtl_nic/rtl8168fp-3.fw for module r8169

After reboot result is same as before (same error with usual 18.04 boot menu choice, still works with advanced options choice)

-- 2nd Response to @heynnema --

fdisk:

$ sudo fdisk -l
Disk /dev/loop0: 32.3 MiB, 33865728 bytes, 66144 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop1: 704 KiB, 720896 bytes, 1408 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop2: 243.9 MiB, 255762432 bytes, 499536 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop3: 276 KiB, 282624 bytes, 552 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop4: 2.5 MiB, 2621440 bytes, 5120 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop5: 32.3 MiB, 33853440 bytes, 66120 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop6: 2.4 MiB, 2555904 bytes, 4992 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop7: 61.7 MiB, 64729088 bytes, 126424 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/nvme0n1: 1.9 TiB, 2048408248320 bytes, 4000797360 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 63850E58-ACD2-4B55-B5D5-29E46C830D03

Device              Start        End    Sectors   Size Type
/dev/nvme0n1p1       2048    1050623    1048576   512M EFI System
/dev/nvme0n1p2    1050624 2029461901 2028411278 967.2G Linux filesystem
/dev/nvme0n1p3 2029463552 4000796671 1971333120   940G Linux filesystem




Disk /dev/loop8: 65.1 MiB, 68259840 bytes, 133320 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop9: 548 KiB, 561152 bytes, 1096 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop10: 2.5 MiB, 2605056 bytes, 5088 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop11: 219 MiB, 229638144 bytes, 448512 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop12: 2.2 MiB, 2342912 bytes, 4576 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop13: 219 MiB, 229629952 bytes, 448496 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop14: 64.8 MiB, 67915776 bytes, 132648 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop15: 548 KiB, 561152 bytes, 1096 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop16: 55.4 MiB, 58130432 bytes, 113536 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop17: 55.5 MiB, 58134528 bytes, 113544 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/loop18: 61.8 MiB, 64770048 bytes, 126504 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

blkid:

$ sudo blkid
/dev/loop0: TYPE="squashfs"
/dev/loop1: TYPE="squashfs"
/dev/loop2: TYPE="squashfs"
/dev/loop3: TYPE="squashfs"
/dev/loop4: TYPE="squashfs"
/dev/loop5: TYPE="squashfs"
/dev/loop6: TYPE="squashfs"
/dev/loop7: TYPE="squashfs"
/dev/nvme0n1: PTUUID="63850e58-acd2-4b55-b5d5-29e46c830d03" PTTYPE="gpt"
/dev/nvme0n1p1: UUID="B97B-4975" TYPE="vfat" PARTLABEL="EFI System Partition" PARTUUID="b1d40bc5-1bc0-490b-92d4-256bad74c673"
/dev/nvme0n1p2: UUID="cdc92bbb-f4d8-4a31-9cbf-5215632adb49" TYPE="ext4" PARTUUID="3079da12-a09d-4a1a-a21a-61af34810c23"
/dev/nvme0n1p3: UUID="93b02138-35e3-4446-a2b9-e16cf6c22786" TYPE="ext4" PARTUUID="51df7e8c-fa57-4275-9348-27902134ee6a"
/dev/loop8: TYPE="squashfs"
/dev/loop9: TYPE="squashfs"
/dev/loop10: TYPE="squashfs"
/dev/loop11: TYPE="squashfs"
/dev/loop12: TYPE="squashfs"
/dev/loop13: TYPE="squashfs"
/dev/loop14: TYPE="squashfs"
/dev/loop15: TYPE="squashfs"
/dev/loop16: TYPE="squashfs"
/dev/loop17: TYPE="squashfs"
/dev/loop18: TYPE="squashfs"

Based on one of the answers to this post How can I detect whether my disk is using GPT or MBR from a terminal? I did:

$ sudo ls
 aws                  IntelliScan_Haze_Class_005   pycharm
 awscliv2.zip             IntelliScan_Images_005       rotated_IntelliScan_Images_007
 Desktop              IntelliScan_Images_006       snap
 Documents            IntelliScan_Images_007       temp
 Downloads            minicom.log          temp2.txt
 Downloads2           Music            Templates
 Dropbox             'Nala devices'        temp.txt
 eclipse              Nala_PVT3_2mm_lens_haze      Videos
 examples.desktop         Pictures            'Volumetric Dummy Devices.txt'
 IntelliScan_Haze_Class_001   Public               workspace-apps
 IntelliScan_Haze_Class_002   PVT3_haze            workspace-prod
 IntelliScan_Haze_Class_003   PVT4
 IntelliScan_Haze_Class_004  'PVT4 IMEIs.txt'

then:

$ sudo fdisk -l | grep -B 5 Disklabel

Disk /dev/nvme0n1: 1.9 TiB, 2048408248320 bytes, 4000797360 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt

So it seems I'm using GPT formatting

-- 3rd Response to @heynnema --

Yes I did use Grub Customizer, did that jack things up? I've heard it can do that but I've never had a problem before. Here is my ls -al /etc/grub.d:

$ ls -al /etc/grub.d
total 100
drwxr-xr-x   5 root root  4096 Aug 19 11:00 .
drwxr-xr-x 140 root root 12288 Aug 19 10:32 ..
-rwxr-xr-x   1 root root 10046 Jul 30  2020 00_header
-rwxr-xr-x   1 root root  6258 Jul 20  2020 05_debian_theme
-rwxr-xr-x   1 root root   914 May 23 22:55 10_linux_proxy
-rwxr-xr-x   1 root root   221 May 23 22:55 40_custom_proxy
-rwxr-xr-x   1 root root   914 May 23 22:55 41_linux_proxy
-rwxr-xr-x   1 root root 11298 Jul 30  2020 44_linux_xen
-rwxr-xr-x   1 root root  1992 Jan 28  2016 45_memtest86+
-rwxr-xr-x   1 root root  1539 May 23 22:55 46_os-prober_proxy
-rwxr-xr-x   1 root root  1418 Jul 30  2020 47_uefi-firmware
-rwxr-xr-x   1 root root   285 May 23 22:55 48_custom_proxy
-rwxr-xr-x   1 root root   216 Jul 30  2020 49_custom
drwxr-xr-x   4 root root  4096 May 23 22:55 backup
drwxr-xr-x   2 root root  4096 May 23 22:55 bin
drwxr-xr-x   2 root root  4096 May 23 22:55 proxifiedScripts
-rw-r--r--   1 root root   483 Jul 30  2020 README
-rw-r--r--   1 root root   272 May 23 22:55 .script_sources.txt

-- 4th Response to @heynnema -- grep -i 5.4.0-70 /etc/grub.d/*:

$ grep -i 5.4.0-70 /etc/grub.d/*
/etc/grub.d/10_linux_proxy:-'SUBMENU' as 'Advanced options for Ubuntu'{-'Advanced options for Ubuntu'/*, -'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-73-generic'~408f07b7e0dd8d620374c5b681855861~, -'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-73-generic (recovery mode)'~003de087994ae2af14e29d21bf9905b2~, -'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-72-generic'~c5a297cf454d7588afd791e38e600c79~, -'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-72-generic (recovery mode)'~fdd81b462724bdc5fe27e5506ee615f4~, -'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-70-generic'~6f6c570f06cb15f97ea26de817f5f40a~, -'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-70-generic (recovery mode)'~6b0d22eb9c2641ea1add550c2162c631~}
/etc/grub.d/41_linux_proxy:+'SUBMENU' as 'Advanced options for Ubuntu'{+'Advanced options for Ubuntu'/*, +'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-73-generic'~408f07b7e0dd8d620374c5b681855861~, +'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-73-generic (recovery mode)'~003de087994ae2af14e29d21bf9905b2~, +'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-72-generic'~c5a297cf454d7588afd791e38e600c79~, +'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-72-generic (recovery mode)'~fdd81b462724bdc5fe27e5506ee615f4~, +'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-70-generic'~6f6c570f06cb15f97ea26de817f5f40a~, +'Advanced options for Ubuntu'/'Ubuntu, with Linux 5.4.0-70-generic (recovery mode)'~6b0d22eb9c2641ea1add550c2162c631~}
grep: /etc/grub.d/backup: Is a directory
grep: /etc/grub.d/bin: Is a directory
grep: /etc/grub.d/proxifiedScripts: Is a directory

It seems 5.4.0-70 is in grub.d!! Perhaps this is the problem?

cat /etc/fstab:

$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/nvme0n1p2 during installation
UUID=cdc92bbb-f4d8-4a31-9cbf-5215632adb49 /               ext4    errors=remount-ro 0       1
# /boot/efi was on /dev/nvme0n1p1 during installation
UUID=B97B-4975  /boot/efi       vfat    umask=0077      0       1
/swapfile                                 none            swap    sw              0       0

-- 5th Response to @heynnema --

Here is my Grub Customizer edit screen for the regular Ubuntu 18.04 menu item:

I don't understand this b/c -73 is here not -70 ?!?!

-- 6th Response to @heynnema --

Main Grub Customizer screen:

I just installed FreeCAD on Ubuntu 20.04 and opened a .stp file, which seems to be valid.

While attempting to work out how to rotate/pan, I found various pages upon Googleing (for example https://wiki.freecadweb.org/Manual:Navigating_in_the_3D_view) which list the usual suggestions one would expect (some combinations of left mouse button, Ctrl, Alt, Shift, and the Windows key). None of these work.

I recall something when using some other program about that Ubuntu preempts the use of certain key combinations which makes this type of functionality not work with some programs. Is there a way around this? For example in Google Maps holding Ctrl + left mouse button rotates as expected, the same as in Windows, so I know it's possible to make it work if the developers do certain things. Is there a way around this limitation in FreeCAD on Ubuntu or am I doing something wrong? FreeCAD isn't of much use if the view can't be rotated/panned.

I'm attempting to download the Waymo Open Dataset on Ubuntu 20.04 and I'm running into one problem after another. First I went here:

https://waymo.com/open/download/

Entered my name, etc., then under "Perception Dataset" I choose chose the v1.2 "individual files" link which leads to:

https://console.cloud.google.com/storage/browser/waymo_open_dataset_v_1_2_0_individual_files

I've used various cloud services before but I have not used Google Cloud Platform before. I checked all the boxes, then choose "Download":

A pop-up box appeared instructing to enter this command:

gsutil -m cp -r \
  "gs://waymo_open_dataset_v_1_2_0_individual_files/domain_adaptation/" \
  "gs://waymo_open_dataset_v_1_2_0_individual_files/testing/" \
  "gs://waymo_open_dataset_v_1_2_0_individual_files/training/" \
  "gs://waymo_open_dataset_v_1_2_0_individual_files/validation/" \
  .

I ran the command, and got an error "gsutil not recognized", so I did:

sudo apt-get install gsutil

Then ran the recommended command again, upon which I got this error:

Unknown option: m
No command was given.
Choose one of -b, -d, -e, or -r to do something.

After some Googling I found this post:

https://stackoverflow.com/questions/61417140/installing-gcloud-gsutil-on-ubuntu-18

so I did:

echo "deb [signed-by=/usr/share/keyrings/cloud.google.gpg] http://packages.cloud.google.com/apt cloud-sdk main" | sudo tee -a /etc/apt/sources.list.d/google-cloud-sdk.list

curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key --keyring /usr/share/keyrings/cloud.google.gpg add -

sudo apt-get update

sudo apt-get install google-cloud-sdk

Now when I run the recommended command above I get:

$ gsutil -m cp -r \
>   "gs://waymo_open_dataset_v_1_2_0_individual_files/domain_adaptation/" \
>   "gs://waymo_open_dataset_v_1_2_0_individual_files/testing/" \
>   "gs://waymo_open_dataset_v_1_2_0_individual_files/training/" \
>   "gs://waymo_open_dataset_v_1_2_0_individual_files/validation/" \
>   .
ServiceException: 401 Anonymous caller does not have storage.objects.get access to the Google Cloud Storage object.
CommandException: 1 file/object could not be transferred.

This dataset is public so a password or equivalent should not be necessary. Has anybody else using Ubuntu gotten this dataset to download successfully? I've download other autonomous car datasets (Lyft Level 5, Kitti, etc.) and also used AWS on this same computer without running into problems. What am I doing wrong?

I just came across a file ending in .azip that I need to unzip. Upon some Googling I found this:

https://azip.sourceforge.io/
https://sourceforge.net/projects/azip/
https://sourceforge.net/projects/azip/files/

It seems this is a Windows only program. Is there an Ubuntu utility that will unzip .azip files?

I should mention I tried unzip on the off change it would work, it did not, here is the error:

$ unzip my_file.azip

Archive:  my_file.azip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of my_file.azip or
        my_file.azip.zip, and cannot find my_file.azip.ZIP, period.

I've been using Ubuntu 20.04 for a few months now and things are going well, however recently I ran into 2 legacy applications which I'll need to start supporting that will require Python 2. As best as I can figure, I have at least the following choices:

• Go back to Ubuntu 18.04.5
• Install Python 2 in Ubuntu 20.04
• Attempt to install Python 2 in Ubuntu 20.04 but only in a virtual environment
• Use a VM

I'd prefer to stay away from the VM option b/c I use GPUs frequently which won't go through a VM and also b/c I do a lot of hardware/software interfacing for which using a VM may cause various problems. Also I don't like VMs generally (crashes, mouse/keyboard/screen hiccups, slow performance, etc.)

I'll be honest and admit I don't use virtual environments much, however I can say I'm not inclined towards this option as the 2 legacy applications I'm going to be supporting call Python various places (calling files that start new processes, etc.) that I suspect a virtual environment won't be able to handle. Also, I'v read about problems with an entire separate version of Python in a virtual environment, ex How to create python2.7 virtualenv on Ubuntu 20.04.

Ubuntu 18.04.5 was great but I'd prefer not to backdate at this point, which leaves me to consider installing Python 2. Upon a quick Googling I found many sites that explain the steps to install Python 2 in Ubuntu 20.04 (ex https://linuxconfig.org/install-python-2-on-ubuntu-20-04-focal-fossa-linux or https://www.vultr.com/docs/how-to-install-python-2-on-ubuntu-20-04), and most of these even include instructions on how to use update-alternatives to make python default to Python 2, which is a necessity in my case for supporting one of the legacy options I mentioned earlier.

I find it odd that something as major as installing an entire other version of Python does not cause problems with Ubuntu, since many Linux utilities today use Python. On the other hand Python 2 is offered as an official package by Canonical https://packages.ubuntu.com/focal/python2 and they are generally very good about package integration.

At this time here are my questions:

1. Can anybody that has installed Python 2 in Ubuntu 20.04 clarify if this caused problems? Are there any common applications that won't work after installing Python 2? Any other "gotchas" I should know about or look out for pertaining to this?

2. If I continue with the instructions above (update-alternatives to make python default to Python 2) will that potentially cause problems? Any "gotchas" pertaining to this additional step in particular?

3. Has anybody tried a Python 2 virtual environment configuration (without a Python 2 native install) in Ubuntu? Is it really as easy as this page https://computingforgeeks.com/how-to-install-python2-with-virtualenv-on-ubuntu/ makes it sound? Will virtual environments work for supporting significant applications that call other scripts, use python (expecting it to be Python 2), span/fork other processes, etc?

4. If the native Python 2 install on Ubuntu 20.04 and/or the virtual environment options are problematic, are there any other good options I haven't covered here?

I recently changed from Ubuntu 18.04 to Ubuntu 20.04 and overall I'm very pleased with 20.04, however one odd thing I've since experienced is that Slack (desktop version) does not successfully play the typing-like sound when a message is received. The icon on the top right still has the circle turn red.

If I play a YouTube video I hear it well so I know my speakers are working.

In Settings under Sound, then Alert Sound if I choose different sounds these work:

In Settings under Notifications, then Slack, I have Notifications and Sound Alerts turned on:

Within Slack itself it seems I have things set correctly:

On this last screen if I press Show an Example or change the setting under the Notification sound drop-down I am able to hear the different sounds from within Slack, but they still don't play when a message arrives.

This may sound like a trial matter, however it's caused me to not respond to some urgent messages when working from home recently and therefore is a significant concern. Unfortunately I don't always notice the small circle in the top right corner turning red if I'm really into what I'm doing.

I've tried uninstalling and reinstalling Slack, no change. I never had this problem with Ubuntu 18.04.

Has anybody else had this happen or is there anything else I should check?

Having used Ubuntu 18.04 for a handful of years now, and reading that Python 2 has been removed from Ubuntu 20.04, I was looking forward to using the commands python or pip rather than python3 or pip3. So today I tried Ubuntu 20.04 for the first time, and found:

$ python --version

Command 'python' not found

$ python3 --version
Python 3.8.5

I was surprised and upon looking into things further found the following about the package python-is-python3:

https://packages.ubuntu.com/focal/python-is-python3

https://launchpad.net/ubuntu/focal/+package/python-is-python3

How to make 'python' program command execute Python 3?

The middle of these 3 links is the most descriptive, but none are especially clear about what python-is-python3 is/does and the full scope of ramifications if sudo apt-get install python-is-python3 was to be ran on a Ubuntu 20.04 install.

Here are some questions I have about python-is-python3:

1. Is python-is-python3 proprietary to Ubuntu/Canonical? If so, do other Linux distributions use python-is-python3 also or do some other distributions have a similar equivalent?

2. I gather if I was to run python-is-python3 from the command prompt then I could use the command python instead of python3. First can somebody confirm this, and second, does the same go for pip, i.e. pip instead of pip3?

3. The launchpad.net link above mentions creation of a symlink. Does python-is-python3 really just create a single symlink? It seems odd to introduce a package for such a bare bones purpose. Also, if this package is subsequently uninstalled (i.e. sudo apt --purge remove python-is-python3) does this remove the symlink?

4. Are there any commonly used Python 2 packages out there anymore? I can't think of any offhand.

5. Has anybody ran python-is-python3 and then later regretted doing so due to a reason that was not realized ahead of time?

6. It seems the benefit of running python-is-python3 would be not having to add the 3 at the end of Python commands, but the disadvantage is that you would then have a non-standard Ubuntu setup, is this a fair summary of the python-is-python3 benefit/drawback?

Can somebody please provided recommended commands for Ubuntu 18.04 to configure a Python virtual environment that has Python 3.7.x or 3.8.x?

Of course I'm aware that upgrading the general Ubuntu 18.04 Python install past 3.6.9 (the current Ubuntu 18.04 Python version if all updates have been done) could have disastrous consequences for many other OS functionalities so of course this is not something I'd like to try.

If you're wondering, I need access to some of the asyncio functionality for a WebSockets application that has been introduced after Python 3.6.9.

This post hints at how to do it, but it's very old and does not provide complete instructions. Also I'm unclear on venv vs virtualenv.

Is there a way to configure Ubuntu 18.04 to open Jupyter Notebooks with a double click from the graphical file browser?

There are 2 prominent Stack Overflow posts on the subject:

https://stackoverflow.com/questions/30953227/double-click-to-open-an-ipython-notebook

https://stackoverflow.com/questions/30953227/double-click-to-open-an-ipython-notebook/30955613

But most of the answers here pertain to MacOS, and the few relating to Linux did not seem to work for me on Ubuntu 18.04.

Something completely different from the above that I tried was to make a desktop file:

cd ~/.local/share/applications
gedit jupyter_notebook.desktop

In Gedit I entered this:

[Desktop Entry]
Comment=
Terminal=false
Name=JupyterNotebook
Exec="jupyter notebook" %f
Type=Application

But this did not work. Double-clicking on a .ipynb file still opens it in Chrome and shows the .json contents rather than running it as a notebook.

Has anybody actually gotten this functionality to work with Ubuntu 18.04?

I'm using a laptop running Ubuntu 18.04 with one built-in webcam (integral to the monitor), and I'm attaching multiple other webcams.

I'd like to disable the built-in webcam only, and continue to allow for as many other cameras as I choose to connect. Is there an elegant way to do this in Ubuntu 18.04?

All the current info I can find on this topic suggests sudo modprobe -r uvcvideo and sudo modprobe uvcvideo to disable and enable webcams temporarily and editing /etc/modprobe.d/blacklist.conf to disable webcams persistently after a reboot, but both of these methods seem to turn on or off all webcams, not only the built-in webcam or a certain specified webcam.

Generally I really like Ubuntu 18.04, but one "feature" that I'm not a fan of is the notifications at the top of the graphical file browser after an event pertaining to files (copy, delete, etc.), ex:

Is there a way to suppress these messages?

Somebody in the questions asked why I'd like to suppress these messages. The reason is I find this distracting, and additionally it blocks the view of the files on the top row. This is a substantial hindrance when I'm moving many files around.

Further, anybody who has used computers much is aware that Ctrl+Z will undo an operation, so this message is really not necessary or beneficial.

I'm attempting to follow this post

How to install Point Cloud Library v1.8 (pcl-1.8.0) on Ubuntu 16.04.2 [LTS] for C++?

However, I'm using Ubuntu 18.04 rather than 16.04.

If I do this command on 18.04:

sudo apt-get install qt-sdk

I get:

Unable to locate package qt-sdk

Per this link:

https://packages.ubuntu.com/search?keywords=qt

It seems that qt-sdk was a package for 14.04 and 16.04 but is no longer a package for Ubuntu 18.04. Can anybody suggest the 18.04 equivalent so I can continue with the PCL install in the above linked post?

Title pretty much says it all, I'm aware that since Ubuntu 15.04 systemd is the default service management tool, but can we still use Upstart with 18.04 if we'd like?

If we can still use Upstart with Ubuntu 18.04, has Canonical announced a specific release where Upstart won't work any longer, or are we on our own to try and use Upstart with current/future Ubuntu versions until it doesn't work in a particular case?

Will Ubuntu 18.04 ship with Upstart in addition to systemd, or do we have to install Upstart separately?

Before somebody marks this as a duplicate, I realize this post:

Upstart or Systemd

states that Upstart was used through 14.10 and that now systemd is the default, but my question is can we still use Upstart with 18.04 even if it's not the default.

relatively new Ubuntu user here (but very familiar with OpenCV use on Windows). Having read this post:

What is the Linux equivalent to Windows' Program Files?

It's clear that there is not a direct Ubuntu/Linux equivalent of "Program Files" or "Program Files (x86)" in Windows.

For OpenCV installation, I followed this page:

http://milq.github.io/install-opencv-ubuntu-debian/

which essentially involves going to here:

https://github.com/milq/milq/tree/master/scripts/bash

and running 3 scripts:

install-additional-cli-software.sh

install-additional-gui-software.sh

install-opencv.sh

This works like a champ with Ubuntu 16.04, however I'm not clear on which directory to perform these steps from and therefore have the install located in.

If I open up a terminal by default it goes to the home directory for the current user, in my case for example that would be "/home/cdahms"

This seems like a very bad place to locate an OpenCV download/build/install (still not sure which to call it, again, relatively new to Linux) for at least the following reasons:

-The home directory is often used for other stuff and locating OpenCV here may result in inadvertent modification at a later time
-If a computer ever has multiple users it does not seem to make sense to place OpenCV in a certain user's home directory
-A home directory does not seem like a proper directory for a software install generally speaking

Based on this:

https://github.com/opencv/opencv/blob/master/CMakeLists.txt

line 41:

set(CMAKE_INSTALL_PREFIX "/usr/local" CACHE PATH "Installation Directory")

I'm under the impression that I should cd to "/usr/local", then run the above OpenCV install script. Is this correct? Where are most Ubuntu/OpenCV users installing to?

Note: I should mention that I'm NOT using the apt-get package "libopencv-dev" since that is on OpenCV version 2.4.9 currently, which is about 3.5 years old now. Does anybody have any ideas as to why this package is not updated more often?