rsync is a powerful and widely used command-line utility in Unix-like operating systems that facilitates efficient and reliable file synchronization and data transfer between directories or across different machines. It is particularly useful for remote backups, mirroring, and incremental transfers. The name “rsync” stands for “remote synchronization.”

Basic Syncing

Syncing Folder src into dest

To synchronize the contents of a local folder src into another local folder dest, you can use the following command:

In Linux, the tar command is commonly used for archiving and extracting files and directories. Tar archives can be compressed to save space using various compression algorithms like gzip (*.tar.gz) or bzip2 (*.tar.bz2). This guide will cover how to create, extract, and work with tar compressed archives in Linux.

Compressing Files and Directories with Tar

1. Create a Tar Archive

To create a tar archive of a folder, use the tar -cvpf command:

The provided command is a shell script written in Bash that iterates through directories in the current directory, checks if an archive file (.tar.gz) already exists for each directory, and if not, it creates a compressed archive of the directory using the tar command.

Here’s an explanation of what the script does:

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for dir in `find . -maxdepth 1 -type d  | grep -v "^\.$" `; do
    if ! [ -e ${dir}.tar.gz ] ; then
        tar -cvzf ${dir}.tar.gz ${dir}
    fi
done

1. for dir in find . -maxdepth 1 -type d | grep -v “^.$” ; do: This line starts a loop that iterates through all subdirectories (excluding the current directory) in the current directory.

The provided Bash commands are useful for listing and deleting files, including dotfiles, except for the newest ones. Here’s a breakdown of what each command does:

List all files except the newest three:

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ls -t | tail -n +4

• ls -t: Lists all files in the current directory sorted by modification time in descending order (newest first).
• tail -n +4: Displays all lines starting from the fourth line. In this context, it shows all files except the newest three.

Delete those files:

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ls -t | tail -n +4 | xargs rm --

• xargs: Takes the output from the previous command (the list of files to delete) and passes them as arguments to the rm (remove) command.
• rm --: Deletes the specified files.

List all dotfiles except the newest three:

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ls -At | tail -n +4

• ls -At: Lists all files, including dotfiles, sorted by modification time in descending order.
• tail -n +4: Displays all lines starting from the fourth line. It shows all dotfiles except the newest three.

Delete dotfiles:

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ls -At | tail -n +4 | xargs rm --

• xargs: Takes the output from the previous command (the list of dotfiles to delete) and passes them as arguments to the rm (remove) command.
• rm --: Deletes the specified dotfiles.

It’s important to use these commands with caution, especially the ones that involve deletion (xargs rm --). Deleting files is irreversible, and there’s no easy way to recover them if you make a mistake. Make sure you’re in the correct directory and that you are certain about the files you want to delete before running these commands.

If you are unable to find the “sudo tmutil disablelocal” command to remove all local copies of Time Machine snapshots, you can manually delete them using the following steps.

Step 1: List Local Snapshot Dates

To begin, open the Terminal application on your Mac and enter the following command:

Avahi is an open-source implementation of zero-configuration networking, also known as Bonjour or mDNS, which allows devices to automatically discover and communicate with each other on a local network without requiring any manual configuration. This guide will walk you through the process of setting up avahi-daemon on Ubuntu, enabling you to reach the hostname ubuntu.local from the host OS, Samba, and through network discovery.

Step 1: Install Avahi Packages

Open a terminal and execute the following command to install the required Avahi packages: