merge latest from main git repo to my fork

This works better than a web-gui initiated pull request when there are conflicts that must be resolved manually. From this link:

# First add the upstream remote:

git remote add upstream https://repoA
git fetch upstream

# Merge in upstream changes:

git checkout master
git merge upstream/master

# Resolve conflicts and push:

git push origin master

# Your pull request should automatically update

skypeforlinux fails to run due to wrong version of libstdc++

Once again skypeforlinux fails to run, this seems to be a weekly occurrence for me. Not sure why it's so fragile. Usually it's due to the permissions problem that I documented a couple of months ago. This time, it's not finding the correct version of libstdc++. I updated the OS and installed anaconda last week, so I'm guessing it's due to one of those actions.

The error message looked like this:

$ /usr/share/skypeforlinux/skypeforlinux
A JavaScript error occurred in the main process
Uncaught Exception:
Error: /lib64/libstdc++.so.6: version `GLIBCXX_3.4.21' not found (required by /usr/share/skypeforlinux/resources/app.asar.unpacked/node_modules/electron-utility/build/Release/electron_utility.node)
at process.func (electron/js2c/asar.js:140:31)
at process.func [as dlopen] (electron/js2c/asar.js:140:31)
at Object.Module._extensions..node (internal/modules/cjs/loader.js:922:18)
at Object.func (electron/js2c/asar.js:140:31)
at Object.func [as .node] (electron/js2c/asar.js:149:18)
at Module.load (internal/modules/cjs/loader.js:735:32)
at Module._load (internal/modules/cjs/loader.js:648:12)
at Module._load (electron/js2c/asar.js:717:26)
at Function.Module._load (electron/js2c/asar.js:717:26)
at Module.require (internal/modules/cjs/loader.js:775:19)

I found this link, and followed some instructions about using the libstdc++ installed under anaconda in the /usr/lib64 directory. Here is a summary of the steps:

strings /usr/lib64/libstdc++.so.6 | grep GLIBCXX # to see the version of libstdc++ in your lib directory
sudo yum install libstdc++ # does nothing, yum says the package is up to date
sudo find / -name "libstdc++.so.6*" # find other installations of libstdc++, including anaconda
sudo cp /home/craig/anaconda3/lib/libstdc++.so.6.0.26 /usr/lib64/ # install libstdc++ from anaconda pkg to lib directory
sudo sudo mv /usr/lib64/libstdc++.so.6 /usr/lib64/libstdc++.so.6.bkp # make a backup of existing lib
sudo ln -s /usr/lib64/libstdc++.so.6.0.26 /usr/lib64/libstdc++.so.6 # make symlink for new lib

growing virtualbox guest centos7 linux VM on windows 10 host

Here's another thing that was a whole lot harder than it seems like it should have been. I found several threads/links that were ALMOST everything I needed to know, but missing a couple of important details that probably weren't relevant to the author's situation so not in their process.

This link is very helpful (and this one) and basically describes the correct process.

The details that were missing from the first link were:

1. modifyhd must be done for each snapshot in the VM, not just the main vdi itself (see this link):

To list all the virtualbox drives, use "c:\Program Files\Oracle\VirtualBox>VBoxmanage list hdds". Then for each one associated with the vm you are growing, use modifyhd: "c:\Program Files\Oracle\VirtualBox>VBoxmanage modifyhd "C:\Users\auto\VirtualBox VMs\craigmcc APS dev\Snapshots\{4841ac14-4e09-4b0b-aa54-9665bb1bd4b3}.vdi" --resize 50000". So in my case I used modifyhd 5 times:

c:\Program Files\Oracle\VirtualBox>VBoxmanage modifyhd "C:\Users\auto\VirtualBox VMs\craigmcc APS dev\craigmcc APS dev 20200306 1620-disk001.vdi" --resize 50000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

c:\Program Files\Oracle\VirtualBox>VBoxmanage modifyhd "C:\Users\auto\VirtualBox VMs\craigmcc APS dev\Snapshots\{97e89522-0465-4f68-bfa9-ca33d790a379}.vdi" --resize 50000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

c:\Program Files\Oracle\VirtualBox>VBoxmanage modifyhd "C:\Users\auto\VirtualBox VMs\craigmcc APS dev\Snapshots\{9eb0ae2e-6b3a-41ba-a212-3c27410d8dbf}.vdi" --resize 50000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

c:\Program Files\Oracle\VirtualBox>VBoxmanage modifyhd "C:\Users\auto\VirtualBox VMs\craigmcc APS dev\Snapshots\{6b89d87f-f0d2-4a10-a64a-0b22fdde66de}.vdi" --resize 50000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

c:\Program Files\Oracle\VirtualBox>VBoxmanage modifyhd "C:\Users\auto\VirtualBox VMs\craigmcc APS dev\Snapshots\{4841ac14-4e09-4b0b-aa54-9665bb1bd4b3}.vdi" --resize 50000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

2. after using "lvextend" you must use "xfs_growfs" to make the space available (this is mentioned in the 2nd link above, but not the first.

After running lvextend, "lsblk" output looked correct, but "df -h" did not show the newly available space. I fixed this by running "sudo xfs_growfs /dev/mapper/centos-root". Now df shows the correct output.

So in a nutshell here are the steps:

1. make the disk partition larger, I used the command line tools shown above whereas the first link does so in vbox manager. "df" doesn't show the available space at this point, unlike the example in the first link above where df does show the space. But gparted does see it...
2. download gparted .iso file
3. mount the .iso file under the vm's storage tab on settings under IDE controller, make sure on system tab that optical is before hard disk in boot order
4. start the vm and run gparted, add the unallocated space to the partition you want to grow (in my case where / is mounted)
5. i had to follow the special LVM instructions in the first link, so in gparted you must "deactivate" the partition with the lock icon before growing it
6. unmount optical disk for gparted and reboot vm
7. display physical volumns with "sudo pvs", should show new free space
8. grow the physical volume with "sudo pvresize /dev/sda2"
9. "lsblk" still shows that the root partition is not using the entire available free space
10. run "sudo lvextend -l +100%FREE /dev/centos/root" to use the entire free space for the logical volume
11. run "sudo xfs_growfs /dev/mapper/centos-root" to grow the logical volume while mounted

centos7 linux laptop can't connect to public wifi portals

It's not always the case, but sometimes/often I can't connect to public wifi portals from my linux laptop that open a login page automatically. The page is never displayed, and I get no internet service (though there is a wifi connection and network setup). This always happens on American Airlines and Delta flights, which is nice.

I did some research and found a couple of threads suggesting that I need to configure the NetworkManager service, and it will open the login page on the captive wifi portal. I found another link on the matter, with details about how to edit the config file. I basically did what it says, though I called the file /etc/NetworkManager/conf.d/20-connectivity-centos.conf. Supposedly this is read by the NetworkManager daemon at startup.

I restarted the daemon using these instructions, since the ones in the ubuntu threads don't work for me. I used "sudo systemctl restart NetworkManager".