To restart the MySQL server on a Linux or Unix system over an SSH connection, you can use the following command: sudo service mysql restart This command uses the sudo command to run the service command with superuser privileges. The service command is used to manage system services, and the mysql argument specifies the MySQL … Read more

To extract a ZIP file in a Linux or Unix-like system, you can use the following command: unzip filename.zip This command will extract the contents of filename.zip into the current directory. The extracted files will have the same permissions and ownership as the original ZIP file. If you want to extract the contents of the … Read more

In shell scripts, using the pattern .* to match dot files (files with names starting with a dot) is considered harmful because it may include unexpected files in the match. This is because .* matches any character zero or more times, including the / character. As a result, the pattern will match hidden files and … Read more

To remove empty lines from a text file in Linux or Unix, you can use the following command: grep . file.txt > output.txt This command uses grep to search for lines that contain a period . and writes the matching lines to a new file called output.txt. This effectively removes all empty lines from the … Read more

To reload the Apache 2 HTTPD configuration file without restarting the Apache service, you can use the following command: sudo apache2ctl graceful The graceful option signals the Apache process to reload the configuration file and apply the changes without interrupting ongoing requests. This allows you to make changes to the Apache configuration file and have … Read more

To wipe all changes and undo all modifications made to a file since it was opened in the vi or vim text editor, you can use the following command: :e! This command discards all changes and reloads the file from disk, effectively undoing all changes made since the file was opened. Note: This will only … Read more

The tar command in Linux is used to create and extract archive files. To create a .tar archive file from one or more files or directories, you can use the following syntax: tar -cvf archive.tar file1 file2 directory1 In this example, -c option is used to create an archive, -v option is used for verbose … Read more

To install the gem package on Debian or Ubuntu, you can use the following steps: Update the package index: sudo apt-get update Install the ruby and rubygems packages: sudo apt-get install ruby rubygems Verify that the gem package is installed by checking the version: gem -v This will output the version number of the gem … Read more

Port knocking is a security technique used to hide services on a network behind a firewall until a specific sequence of connection attempts (knocks) is received. To set up port knocking on Debian or Ubuntu, you will need to install two components: knockd, which acts as the daemon that listens for knocks and opens the … Read more

To uninstall the Apache (HTTPD) server on CentOS or Red Hat Enterprise Linux (RHEL) 5/6, you can use the following steps: Stop the Apache service: service httpd stop Remove the Apache packages: yum remove httpd This will remove the Apache packages and all of its dependencies from your system. Remove any leftover Apache configuration files: … Read more