Removing lines that are in fileB from fileA producing fileC

Problem

You have two different files fileA and fileB containing similar records (one record per line), and you would like to remove the records that fileB contains from fileA (subtract) producing a new file (fileC) that contains only records that are contained in fileA with records from fileB removed.

Solution

Use the following grep command

grep -vxf fileB fileA > fileC

asdf and terraform (or vault or packer)

Using the asdf version manager to manage versions of various binaries like terraform, vault or packer is easily done by following the instructions below:

  1. Download and install asdf if you haven’t got it already (https://asdf-vm.com/#/core-manage-asdf)
  2. If you want to install the latest version of terraform for example do the following:
asdf plugin add terraform
asdf install terraform latest
asdf global terraform 0.14.9
asdf list
terraform
  0.14.9
terraform --version
Terraform v0.14.9

Get/Set platform information

To get or set in environment variables the platform information of a system you can use the following:

export ARCH=$(case $(arch) in x86_64) echo -n amd64 ;; aarch64) echo -n arm64 ;; *) echo -n $(arch) ;; esac)
export OS=$(uname | awk '{print tolower($0)}')

Taken from the installation instructions of the Operator SKD here: https://master.sdk.operatorframework.io/docs/installation/

Failed to start docker.service: Unit is masked

Problem

Trying to start the docker service after some upgrades fails with the following message:

Failed to start docker.service: Unit is masked.

Solution

It turns out that after upgrading or more specifically removing and then upgrading the docker installation in ubuntu (in this particular case in raspberry 4 with Ubuntu 20.04 installed), results in this error.

A search brings up the following:

https://forums.docker.com/t/failed-to-start-docker-service-unit-is-masked/67413

and from that the following bug post:

https://bugs.launchpad.net/ubuntu/+source/docker.io/+bug/1844894

So the solution is to run the following to be able to start the docker service (described in the first link above):

sudo systemctl unmask docker
sudo systemctl start docker

Getting detailed information about your Linux distribution

To be able to get a more detailed information about your current linux distribution, including the code names use the following:

kosmas:$ cat /etc/os-release
NAME="Ubuntu"
VERSION="18.04.5 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.5 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch

Problem

Trying to configure and use an nginx server that uses intermediate certifcates, you get the error about values mismatch and nginx does not start

2020/09/23 09:49:38 [emerg] 20958#20958: SSL_CTX_use_PrivateKey("/etc/ssl/private/cakey.pem") failed (SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch)

Solution

It seems that this is a common mistake and it is mentioned here: https://nginx.org/en/docs/http/configuring_https_servers.html. In order to fix this you will need to change/reverse the original order that you have concatenated the chain, as in:

cat certs/cacert.pem intermediate/certs/intermediate.cacert.pem > intermediate/certs/ca-chain-bundle.cert_new.pem