How to empty the gnome tracker3 cache?

To empty the cache of gnome tracker3, you can follow the steps below:

Open a terminal window by pressing Ctrl + Alt + T.

Type the following command to stop the tracker daemon:

tracker3 daemon -t;

Type the following command to clear the tracker database:

tracker reset --filesystem;

This command will remove all indexed data from the tracker and clear its cache. (Remove filesystem indexer database)

Restart the tracker daemon by typing the following command:

tracker daemon -s ;

This will start the tracker daemon again, and it will begin to rebuild its database and cache.

After following these steps, the cache of gnome tracker3 will be emptied.

Execution example:

$ tracker3 daemon -t
Found 1 PID…
  Killed process 13705 — “tracker-miner-fs-3”
$ tracker3 reset --filesystem
Found 1 PID…
  Killed process 13705 — “tracker-miner-fs-3”
$ tracker3 daemon -s
Starting miners…
  ✓ File System

5 packages can be upgraded. Run ‘apt list –upgradable’ to see them.

Updating an operating system is a critical task that ensures the system’s security, stability, and performance. In Ubuntu, updating the system involves running several commands in the terminal. In this technical post, we will explain the process of updating an Ubuntu Server installation and how to fix the issue of pending package upgrades.

The first command that needs to be executed is sudo apt update. This command updates the list of available packages from the Ubuntu repositories. The -y option instructs the system to answer “yes” to prompts, ensuring the process runs uninterrupted.

The second command is sudo apt upgrade. This command upgrades all installed packages to their latest versions. Again, the -y option is used to answer “yes” to any prompts.

The third command, sudo apt autoremove, removes any unnecessary dependencies that are no longer required by the system.

After executing these three commands, the system displayed a warning message that says that five packages can be upgraded. To see the list of upgradable packages, we needed to execute the command apt list --upgradable. This command lists all the upgradable packages along with their versions.

The following command we executed was sudo apt-get dist-upgrade. This command upgrades the system to the latest distribution release, including kernel upgrades. However, the command failed to upgrade the pending packages in this case.

To fix the issue, we executed the command sudo apt-get install --only-upgrade $PACKAGE for each pending package. This command upgrades the specified package to its latest version. The $PACKAGE variable should be replaced with the package name that needs to be upgraded.

In summary, updating an Ubuntu Server installation involves running the sudo apt update, sudo apt upgrade, and sudo apt autoremove commands in the terminal. If there are any pending package upgrades, we can use the apt list --upgradable command to see the list of upgradable packages. If the sudo apt-get dist-upgrade command fails to upgrade the pending packages, we can use the sudo apt-get install --only-upgrade $PACKAGE command to upgrade each package individually.

Using nmap to scan a network and identify which hosts are alive

The command “nmap -sP” scans a network and identifies which hosts are alive (i.e., which IP addresses are being used) within the specified range.

In more detail, the “nmap” command is a widely used network exploration tool that can be used for tasks such as host discovery, port scanning, and service enumeration.

The “-sP” option tells nmap to perform a “ping scan,” where it sends an ICMP echo request to each host in the specified IP range and checks for responses. This method is typically faster than other scanning techniques because it only determines whether a host is up or not without gathering additional information about the host’s ports or services.

The “” argument specifies the IP range to be scanned, specifically the subnet mask “,” which corresponds to the range of IP addresses from to The “/24” suffix is a shorthand notation for the subnet mask.

Overall, the command “nmap -sP” is a helpful tool for network administrators or security professionals who need to identify which hosts are active on a particular network quickly. It can help to identify potential security vulnerabilities or unauthorized devices connected to the network.

Unable to negotiate with IP port 22: no matching host key type found. Their offer: ssh-rsa

Secure Shell (SSH) is a cryptographic network protocol that is commonly used for secure data communication, remote command-line login, and other network services. The SSH command is used to remotely connect to a server or device and execute commands on that device. In this blog post, we will explain the following SSH command and when the extra parameters are needed.

ssh -p 22 -o HostKeyAlgorithms=+ssh-rsa -o PubkeyAcceptedKeyTypes=+ssh-rsa [email protected];

Breakdown of the SSH command

  • ssh: The command to initiate a Secure Shell connection to a remote host.
  • -p 22: The -p option specifies the port number that SSH should use to connect to the remote host. In this case, the port number is 22, which is the default SSH port number.
  • -o HostKeyAlgorithms=+ssh-rsa: The -o option allows the user to set SSH options. In this case, the option HostKeyAlgorithms specifies the key exchange algorithm that should be used for the connection. The +ssh-rsa parameter adds the ssh-rsa algorithm to the list of acceptable algorithms.
  • -o PubkeyAcceptedKeyTypes=+ssh-rsa: Similar to the previous parameter, this option specifies the type of public key that will be accepted for authentication purposes. The +ssh-rsa parameter adds the ssh-rsa key type to the list of acceptable key types.
  • [email protected]: Specifies the username and hostname of the remote machine to connect to.

When are the extra parameters needed?

The extra parameters in this SSH command are used to specify the key exchange and authentication algorithms that are acceptable for the SSH connection. This is important because older, less secure algorithms can be vulnerable to attacks. By specifying only the more secure algorithms, you can help ensure that your connection is as secure as possible.

The specific parameters used in this command are not always necessary, but they can be useful in certain situations. For example, if you are connecting to an older SSH server that uses weaker encryption algorithms, you may want to specify only the stronger algorithms that are supported by both the server and your client. Similarly, if you are connecting to a server that requires a specific type of public key for authentication, you can specify that key type using the PubkeyAcceptedKeyTypes option.

In general, it’s a good idea to use the most secure algorithms that are supported by both your client and the remote server. This can help ensure that your connection is as secure as possible and minimize the risk of unauthorized access or data breaches.

In conclusion, the SSH command is a powerful tool for remotely connecting to and managing servers and devices. By understanding the different parameters and options available, you can customize your SSH connections to meet your specific needs and ensure that your connections are as secure as possible.