Install packages

pamac install package_name

Install packages without confirmation

I’m so used to Debian and Ubuntu and I always feel the need to surpress the “Yes/No” questions during package installation. So, on Manjaro you can just use the –no-confirm option in order to install them automatically:

pamac install --no-confirm package_name

Remove packages

pamac remove package_name

Remove a package and its no longer required dependencies

Which are called orphans:

pamac remove --orphans package_name

Remove packages only if they are not required by any other packages

pamac remove --unneeded, u

Search for packages

pamac search package_name

List all installed packages

pamac list --installed

Check for package updates

pamac checkupdates

Error: creating EC2 Instance: VPCIdNotSpecified: No default VPC for this user. GroupName is only supported for EC2-Classic and default VPC.

The error refers to the user not having access to the proper AWS resources declared in the Terraform code. Like trying to access an EC2 instance in the wrong AWS zone region. So, basically Terraform will try to create an EC2 instance of an Ubuntu server using the region, AMI id and instance type provided in the code but it will not find those things thus the error.

To make sure you’re providing the correct info about your AWS resources:

• choose the region your project needs to be into (us-east-1, eu-west-1, etc.);
• for choosing the proper AMI (Amazon Machine Images) with its proper id, browse to AWS Management Console > EC2 > Images > AMIs catalog;
• then, depending on the requirement of your project, choose a proper instance type by going to AWS Management Console > Instances > Instance types.

For example:

provider "aws" {
  region = "eu-west-2"
}
resource "aws_instance" "ec2" {
  ami = "ami-0a6006bac3b9bb8d3"
  instance_type = "t2.micro"
}

How to append text to a file in Linux using the tee command

The tee -a command (or tee –append) can be used to append (write at the end of the file) the current logged in user to the sudoers file:

echo $USER | sudo tee -a /etc/sudoers 

How to append text to a file in Linux using the cat command

You can append text to a file in Linux using the cat command in combination with with EOF (End Of File):

cat >> /etc/sudoers << EOF
busyneo    ALL=(ALL:ALL) ALL
EOF

You can notice that in the above example, I’m basically marking the start and the beginning of my text that I need inserted into the sudoers file by using EOF.

Basic commands in Alpine linux

• You can check the current apk version by running the following command:

apk --version

Packages and repositories in Alpine linux

• Remove all the old formed cache from packages in Alpine linux by running the following command:

apk cache clean
apk -v cache clean

• Start fresh: clean packages caches and download missing packages in Alpine linux using the following command:

apk cache -v sync

• For example, in order to update and upgrade Alpine linux repositories:

apk update && apk upgrade

• To view all packages available in Alpine linux, we can use:

apk search -v

• To search for a particular package and in their description in Alpine linux, we can use:

apk -v -d "package_name"

• Or to confirm installation of the packages in Alpine linux, using the following command:

apk add package_name1 package_name2

• Or to confirm package upgrade in Alpine linux:

apk upgrade package_name

• To delete a specific package in Alpine linux, we can use the following command:

apk del package_name1 package_name2

• To view all current installed packages in Alpine linux, we can use the following command:

apk info

• To check if a certain package is installed in Alpine linux, we use the following command:

apk -e info package_name

• And if we need to manually install an .apk package in Alpine linux, we can use the following command:

apk --allow-untrusted path/to/package1.apk path/to/package2.apk

Ubuntu / Debian based Linux distributions

If you’re using an Ubuntu or Debian based distribution, you can use the free version of unrar and you can install it using the following command:

sudo apt install -y unrar-free

Create a folder and extract your files inside it using the following command:

unrar -x yourfile.rar /path/to/your/folder/

As you may have noticed, the -x flag is actually telling the program to start the extraction process. And you can also use the:

• -p flag, if you’re extracting from a password protected .rar archive;
• -f flag, if you want to force/overwrite the files during the extraction process;
• -t flag, to just list the files within a .rar archive;
• -v flag, to check the software’s version.

Red Hat Enterprise Linux (RHEL) based Linux distributions

If you’re using a RHEL based distribution such as, CentOS, for example, you can use the unar package; the thing is, you’ll first have to install the epel-release package and then you’ll be able to install:

sudo yum install -y epel-release
sudo yum install -y unar

But if you’re using, let’s say, Fedora, then you can just use the following command:

sudo dnf install -y unar

Now, in order to extract the .rar archive using the unar package, you can use the following command:

unar yourfile.rar

So, there are 2 ways you can fix this:

1. You check your main/local router’s DNS settings.
2. You manually add a DNS server to your current host by:

• editing /etc/resolv.conf and adding the following line:

nameserver 8.8.8.8

• updating the repositories, again:

sudo yum update -y

For starters, in order to get an overview of all your disk usage from the Docker images, containers, build cache size and so on, you can use the following command:

docker system df

But if you need a more detailed view, describing every Docker item that takes up resources in each category (volumes, images, etc.), you can just add the -v (verbose) flag to the command above:

docker system df -v
# or docker system df --verbose

You can also use the -s flag to the ps command and get each Docker container’s size:

docker ps -s
# or docker ps --size

docker inspect -f "{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}" container_ID_or_name

But you can also use grep:

docker inspect container_name | grep "IPv4"

docker events &

By this point, any Docker command that you’ll run next will be viewed with more logs.

2. Execute your Docker command (for example: run a container or create an image):

docker container run -d --name nginx-r-p-container --publish 80:80 nginx-reverse-proxy:latest

3. Check the logs of the Docker instance ID that concerns you:

docker logs 250629587af532239d8b165e924f9217134cf662a5ba1ce0855c55f70e152f63

In my case above, I forgot to close my code block with “}”. Thus, the container didn’t run. And that’s how you can use Docker in debug mode.

In order to remove the “none” Docker images, you can use:

docker rmi -f $(docker images --filter "dangling=true" -q --no-trunc)