Linux commands

1

what is jq command in ubuntu

The jq command in Ubuntu, and in general across Unix-like operating systems, is a lightweight and flexible command-line JSON processor. JSON (JavaScript Object Notation) is a popular format for data interchange, being both easy for humans to read and write and easy for machines to parse and generate. The jq tool allows users to slice, filter, map, and transform structured data with the same ease that sed, awk, grep and friends let you play with text.

jq is used to process JSON files in a variety of ways, including:

  • Parsing JSON from standard input (stdin) or from files.

  • Beautifying JSON output, making it more readable.

  • Filtering JSON data to find specific elements.

  • Transforming the data by sorting, slicing, reducing, and mapping elements.

  • Extracting specific fields from JSON objects.

  • Performing arithmetic and string operations on data.

  • Generating JSON objects or arrays from multiple inputs.

Here are some basic examples of how jq can be used:

  1. Pretty-printing JSON:

    cat myfile.json | jq .

    This command will output the contents of myfile.json in a nicely formatted way.

  2. Extracting Values:

    echo '{"name": "John", "age": 31}' | jq '.name'

    This will output "John", extracting the value of the name field from the JSON input.

  3. Filtering:

    echo '[{"name": "John"}, {"name": "Jane"}]' | jq '.[] | select(.name=="John")'

    This filters a list of objects, outputting only those where the name field is "John".

  4. Mapping:

    echo '[{"name": "John", "age": 30}, {"name": "Jane", "age": 25}]' | jq 'map(.name)'

    This produces an array of names, extracting the name field from each object in the input array.

jq is very powerful and supports complex expressions and functions for manipulating JSON. It's widely used in scripting, data processing, and API interactions where JSON is the data format. To start using jq, you can typically install it on Ubuntu and other Debian-based systems with:

Once installed, you can run jq --help or visit the jq man page for more information on its syntax and capabilities.

2

Show all libraries by using dkpg

To list all installed packages on a Debian-based system like Ubuntu, you can use the dpkg command with the -l option. However, this will list all installed packages, not just libraries. Libraries in Debian and Ubuntu packages often have names that end with -dev (for development header libraries), but simply listing packages with -dev in their name might not cover all the libraries you're interested in, as runtime libraries often do not follow this naming convention.

To get a comprehensive list, you can use the following command in the terminal:

If you want to filter this list to show more likely library-related packages, you can use grep with common library naming conventions. For instance, many library packages include -lib in their name or are related to development (-dev). You might try:

This command will still show some non-library packages because it's simply filtering based on text matching. If you're looking for specific libraries, you can refine your grep search pattern.

Remember, the actual library files (such as .so files for shared libraries) are usually placed in /lib, /usr/lib, /usr/local/lib, or similar directories, and not every package that installs files into these directories is a "library" in the sense of being a developer tool. Some are runtime components that applications depend on.

To truly understand what's installed and to manage libraries and other packages, familiarizing yourself with the dpkg and apt suite of commands (including apt-get and apt-cache) is very helpful. You can also use apt-file to find out which packages specific files belong to, which is useful for understanding library installations.

Copy the installed libaries from one system to another:

LogoHow to list all installed packagesAsk Ubuntu

3

How to take screenshots?

In Lenovo Thinkpad, just use the PrintScreen and then you will get options

LogoHow to Take Screenshots on Ubuntu? 4 Different MethodsMUO

4

tell me more about dpkg --get-selections

The dpkg --get-selections command in Debian-based systems like Ubuntu is a useful command for listing all packages marked for installation or deinstallation. When executed, it displays each package followed by its current status in the system. This command doesn't filter its output to show only libraries; instead, it lists all software packages managed by dpkg, the Debian package management system.

Here's a brief overview of how to use the command and interpret its output:

Usage

Simply open a terminal and type:

This will output a list of installed packages along with their status. The most common status you'll see is install, indicating that the package is currently installed on the system.

Interpreting the Output

The output of dpkg --get-selections will be in the following format:

For example:

This indicates that the libc6 package for the amd64 architecture is installed.

Filtering the Output

While dpkg --get-selections provides a comprehensive list, you might often want to filter this output to find specific packages. You can use grep for this purpose. For instance, if you're interested in filtering the output to show only packages related to python, you could use:

Other Operations

Although dpkg --get-selections is great for listing packages, dpkg has a wide range of other options for managing packages. For example, to see detailed information about a specific package, you can use:

To list the files installed by a package, use:

Saving and Restoring Package Selections

One powerful use of dpkg --get-selections is in combination with dpkg --set-selections for replicating installed package selections from one system to another. You can save the selections to a file:

Then, you can set these selections on another system with:

After setting the selections, you can use dselect or apt-get dselect-upgrade to actually install the packages.

Remember, dpkg itself does not handle package downloads or dependency resolution. For tasks involving these, you would typically use a higher-level tool like apt-get or aptitude which builds on dpkg to provide these features.

give me the code to copy the installed libaries from one system to another

To copy the installed libraries (and generally all installed packages) from one system to another in Debian-based systems (like Ubuntu), you'll typically follow a two-step process: first, you'll generate a list of the currently installed packages on the source system, and then you'll use that list to install the same packages on the target system. Below are the steps and the code to do this.

Step 1: On the Source System

  1. Generate a List of Installed Packages You can use dpkg --get-selections to get a list of all installed packages (not just libraries) and redirect the output to a file. While this includes all packages, not just libraries, it's a comprehensive approach to mirroring one system's setup on another:

  1. Copy the List to the Target System You need to transfer the installed_packages.list file to the target system. You can use secure copy (scp), a USB drive, or any method you prefer. If both systems are on the same network and you have SSH access, you can use scp like so:

Replace user with your actual username on the target system, target-system with the hostname or IP address of the target system, and /path/to/destination with the actual path where you want to store the file on the target system.

Step 2: On the Target System

  1. Apply the Package Selections First, make sure the package database is up to date:

Then, apply the package selections from the file you transferred:

Replace /path/to/ with the actual path where you stored the list file.

  1. Install the Packages Finally, tell apt-get to download and install the selected packages. This step will also handle all necessary dependencies:

This process will install the same packages that were installed on the source system, including libraries, applications, and other software, onto the target system. Be aware that this might take some time, depending on the number of packages and your internet speed. Also, this method doesn't differentiate between libraries and other types of packages, as it aims to replicate the software environment from one system to another.

tell more about lintian

Lintian is a powerful and versatile tool used within the Debian ecosystem to check Debian software packages for bugs and policy violations. It automates the process of checking Debian binary and source packages, making it an invaluable resource for package maintainers and developers aiming to ensure their packages adhere to the high standards of Debian's packaging policies.

Here's a closer look at Lintian:

Purpose and Functionality

  • Quality Assurance: Lintian is primarily used for quality assurance purposes. It examines Debian packages (.deb files) and their accompanying metadata for common errors, inconsistencies, and violations of the Debian Policy Manual. This policy manual is a comprehensive set of guidelines that govern how Debian packages should be created and maintained.

  • Automated Checks: It performs automated checks on various aspects of a package, including but not limited to the control files, metadata, file permissions, and the presence of mandatory files like the copyright notice.

  • Policy Compliance: Lintian checks packages for compliance with Debian policy standards, helping maintainers ensure their packages integrate well with the Debian archive and adhere to best practices.

How It Works

  • Check Scripts and Tags: Lintian uses a collection of check scripts that generate tags indicating warnings, errors, or informational messages about a package. These tags help identify specific issues that might need attention. The full list of tags and their meanings can be found in the Lintian documentation or by using the lintian-info command.

  • Comprehensive Database: It includes a comprehensive database of known issues and policies, which is regularly updated to reflect the latest Debian policy standards.

Usage

To use Lintian, you would typically run it from the command line, specifying the package file(s) you want to check. For example:

This command would analyze mypackage.deb and report any issues found. For more detailed output, you can use the -i, -I, or --info flags, which will include detailed explanations for each issue reported:

Integration with Debian Packaging Workflow

  • Package Development: Developers and maintainers use Lintian during the package development and maintenance process to catch and fix issues before submission to the Debian archive.

  • Debian Build Services: Automated systems like Debian build services also use Lintian to perform automated checks on packages submitted to the Debian repositories.

Continuous Improvement

  • Community-Driven Updates: The Lintian tool is open source and community-driven, with updates and improvements made regularly to adapt to new standards and policies within the Debian project.

In summary, Lintian is an essential tool in the Debian packaging ecosystem, facilitating the maintenance of package quality and policy compliance, thereby ensuring the stability and reliability of Debian packages.

5

How to install deb?

To install a .deb package on Debian-based systems (like Ubuntu), you have a few options, depending on whether you want to use a graphical interface or the command line. Here are the most common methods:

Using the Command Line

1. dpkg

The dpkg command is the base tool for handling .deb files on Debian-based systems. To install a package using dpkg, you can run the following command in the terminal:

Replace /path/to/package.deb with the actual path to your .deb file. If the package has unmet dependencies, dpkg will report them but won't fetch them for you. To resolve these dependencies, you can run:

This command tells apt-get to fix any broken dependencies, installing any required packages that weren't installed by dpkg.

2. apt

Starting from version 1.1 of APT, you can use the apt command to install .deb files while automatically handling dependencies. This method is simpler as it combines the installation step and the dependency resolution step into one:

Notice the ./ before the path which is necessary if you are in the directory of the .deb file. If you're providing an absolute path from anywhere in the filesystem, you don't need ./.

Using a Graphical Interface

If you prefer not to use the command line, you can install .deb files using a graphical package installer that comes with your desktop environment.

1. GNOME Software (Ubuntu)

On Ubuntu, if you double-click a .deb file in the file manager (Nautilus), it will open in GNOME Software (or Ubuntu Software) by default. From there, you can click the "Install" button to install the package.

2. gdebi

gdebi is a lightweight GUI tool that can install .deb files while automatically resolving and installing its dependencies. If it's not already installed, you can install gdebi from the terminal:

After installing gdebi, you can right-click on the .deb file in your file manager, select "Open With Other Application", and choose gdebi (or "GDebi Package Installer") from the list.

Using gdebi is a good choice when dealing with standalone .deb files since it takes care of dependencies for you, similar to apt but with a GUI.

These methods should cover most needs for installing .deb packages on Debian-based systems. Always ensure you trust the source of the .deb file before installing it to avoid security risks.

6

talk about Gnome screenshot

GNOME Screenshot is a utility tool provided with the GNOME desktop environment, widely used in Linux distributions, that allows users to capture screenshots and save them as image files. It's a simple yet powerful tool that offers various options for capturing different parts of your screen.

Key Features

  • Whole Screen Capture: You can take a screenshot of your entire screen. This is useful for capturing everything visible on your display at a single point in time.

  • Window Capture: GNOME Screenshot allows you to capture just the currently active window or any window you choose, excluding everything else on the screen. This is handy for focusing on a specific application.

  • Area Selection Capture: You can select a specific area of your screen to capture. After initiating an area capture, you click and drag your mouse to define the area you want to capture. This feature is particularly useful for capturing a specific part of your screen's content without needing to edit the image afterward.

  • Delay Option: The tool provides an option to delay the screenshot capture by a few seconds. This delay is useful if you need to prepare your screen for capture, such as opening a menu or activating a hover effect.

  • Include Pointer Option: It can include the mouse pointer in the screenshot, which is useful for instructional content or demonstrating software usage.

  • Command Line Interface: In addition to its graphical interface, GNOME Screenshot can be used via the command line, offering scripting and automation capabilities.

Using GNOME Screenshot

Graphical Interface

You can start GNOME Screenshot from the applications menu by searching for "Screenshot," or it might be accessible through keyboard shortcuts (which can vary by distribution):

  • PrtScn to take a screenshot of the desktop.

  • Alt + PrtScn to take a screenshot of a window.

  • Shift + PrtScn to take a screenshot of an area you select.

Command Line

For more advanced options or to integrate screenshot taking into scripts, you can use the GNOME Screenshot tool from the command line. Here are some basic examples:

  • Capture the entire screen and save it automatically:

  • Capture a specific area (the tool will let you select an area graphically):

  • Capture the current window:

  • Include the border of the window in the screenshot:

  • Delay the screenshot by a specified number of seconds:

File Saving and Clipboard

By default, screenshots are saved in the user's Pictures directory, but GNOME Screenshot allows you to choose a different location each time you take a screenshot. Alternatively, you can copy the screenshot to the clipboard for immediate use in other applications, avoiding saving the file altogether.

Customization and Settings

While GNOME Screenshot is designed to be straightforward and easy to use, it offers several settings that allow you to customize your screenshot experience, such as default save location, filename format, and whether to include the mouse pointer.

GNOME Screenshot is a quintessential example of GNOME's focus on usability and productivity, providing a seamless experience for capturing screen content in a variety of contexts.

7

how to install gnome-screenshot?

To install gnome-screenshot on a Linux distribution that uses the GNOME desktop environment or supports GNOME applications, you can typically use your distribution's package manager. Here's how you can do it on popular Linux distributions:

On Ubuntu, Debian, and Debian-based distributions

Open a terminal and run the following command:

This command updates your package lists and installs the gnome-screenshot utility.

On Fedora, CentOS (with EPEL repository), and similar distributions

Fedora and recent versions of CentOS come with GNOME Screenshot pre-installed as part of the GNOME desktop environment. If you need to manually install it for some reason, you can use the dnf package manager on Fedora:

On Arch Linux, Manjaro, and Arch-based distributions

On Arch Linux and derivatives, you can use the pacman package manager to install gnome-screenshot:

This command updates your package database and installs gnome-screenshot.

General Notes

  • Pre-installed: In many cases, gnome-screenshot comes pre-installed with GNOME desktop environments. If you're using a GNOME-based distribution, try launching it or checking for it before attempting to install.

  • Dependencies: When installing gnome-screenshot, your package manager will handle any dependencies required by the utility automatically.

  • Using the Application: Once installed, you can usually launch GNOME Screenshot from your applications menu by searching for "Screenshot," or you can use it via terminal or keyboard shortcuts (e.g., PrtScn for the whole screen, Shift + PrtScn for a selected area).

If you encounter any issues or receive error messages during installation, make sure your package lists are updated, or check your distribution's documentation for specific instructions related to your version.

8

how to install jq in ubuntu

To install jq on Ubuntu, you can use the apt package management tool, which is included by default in Ubuntu and other Debian-based distributions. Here are the steps to install jq:

  1. Open a Terminal Window: You can do this by searching for "Terminal" in your applications menu or by pressing Ctrl + Alt + T.

  2. Update Your Package List: Before installing new software, it's a good practice to update the list of available packages to ensure you're installing the latest version. Run the following command:

  3. Install jq: Now, install jq by running:

This command downloads and installs the jq package along with any necessary dependencies.

After the installation is complete, you can verify that jq is successfully installed and check its installed version by running:

This should output the version of jq that you have installed, indicating that the installation was successful.

jq is a powerful tool for processing JSON data directly within the command line or in scripts, allowing you to parse, filter, map, and manipulate JSON-formatted data easily.

9

tell more about mkdir -p

The mkdir command is used in Unix and Unix-like operating systems to create directories. The -p option for mkdir is particularly useful and powerful for creating nested directories in a single command. Here’s a bit more detail about how it works and why you might want to use it:

Basic Usage of mkdir

Without any options, mkdir is used to create a directory:

This command creates a new directory named new_directory in the current working directory. If the directory already exists, mkdir will return an error.

The -p Option

The -p option stands for "parents" and tells mkdir to create any necessary parent directories as needed. If the directories already exist, mkdir -p won't return an error. This makes scripts and commands that use mkdir -p idempotent, meaning they can be run multiple times without causing errors or unexpected results.

Example Usage

Suppose you want to create a directory structure like dir1/dir2/dir3. If dir1 and dir2 don’t already exist, a simple mkdir dir1/dir2/dir3 command would fail because the parent directories are missing. Using mkdir -p, however, ensures the entire path is created:

This command creates dir1, dir2 within dir1, and dir3 within dir2, making the entire directory path if it doesn't already exist. If some or all of the directories already exist, mkdir -p will not return an error.

Benefits of Using -p

  • Simplicity: It simplifies scripts and commands by reducing the number of checks and commands needed to ensure a directory path exists.

  • Safety: It prevents errors if part of your directory path already exists, which is particularly useful in scripts that might be run multiple times or in different environments.

  • Idempotency: It ensures that running the same mkdir -p command multiple times won’t cause errors or unexpected results, which is important for scripting and automation tasks.

Additional Usage Notes

  • Creating Multiple Directories: mkdir -p can also be used to create multiple directory paths in one command by separating each path with a space.

  • Permissions: You can combine -p with the -m option to set permissions on the newly created directories.

In summary, the mkdir -p command is an efficient way to ensure a full directory path is created without having to manually create each individual directory or check for their existence beforehand. It's a common practice in shell scripting and command-line operations to use this option for creating complex directory structures easily.

10

give me a shell script to move the file to specific folder called "~/datasets".

./run.sh abc.txt should copy the abc.txt to datasets

To create a shell script that moves a specified file to a directory called datasets in your home directory, you can follow these steps. This script will take a file name as its argument and move it to ~/datasets. If the ~/datasets directory does not exist, the script will create it.

  1. Open your terminal.

  2. Create the script file:

You can create a new file called run.sh using a text editor. For simplicity, let's use nano:

  1. Write the script:

Copy and paste the following script into the editor:

  1. Save and exit the editor:

If you're using nano, you can save and exit by pressing Ctrl + O, Enter, and then Ctrl + X.

  1. Make the script executable:

Back in the terminal, set the execute permission for your script:

  1. Run the script:

Now, you can move files to ~/datasets by executing the script followed by the file name. For example:

This command will move abc.txt to ~/datasets. If abc.txt does not exist in the current directory, the script will output an error message. If ~/datasets does not exist, the script will create it before moving the file.

11

How to install ffmpeg

Installing ffmpeg can vary slightly depending on your operating system. Below are instructions for installing ffmpeg on various platforms:

Ubuntu and Debian-based Linux Distributions

  1. Update the package list to ensure you have access to the latest versions:

  2. Install ffmpeg by running:

  3. Verify the installation by checking the ffmpeg version:

Fedora and RPM-based Linux Distributions

  1. Install ffmpeg using the dnf package manager:

  2. Verify the installation by checking the ffmpeg version:

Arch Linux and Arch-based Distributions

  1. Install ffmpeg using the pacman package manager:

  2. Verify the installation by checking the ffmpeg version:

macOS

  • If you have Homebrew installed (a package manager for macOS), you can install ffmpeg with Homebrew:

  • Verify the installation by checking the ffmpeg version:

Windows

For Windows, ffmpeg doesn't come as a simple installer but rather as a zip file containing the executables.

  1. Download the latest version of ffmpeg from the official website: FFmpeg Download Page. Choose the Windows build suitable for your system (32-bit or 64-bit).

  2. Extract the zip file to a location on your system, for example, C:\ffmpeg.

  3. Add ffmpeg to your system path:

    • Right-click on This PC or My Computer on your desktop or in File Explorer.

    • Click Properties.

    • Click Advanced system settings.

    • Click Environment Variables.

    • In the System Variables section, find the Path variable, select it, and click

12

How to install ffmpeg

To install ffmpeg on Ubuntu, you can use the apt package management tool. Here are the steps:

  1. Open a Terminal: You can do this by searching for "Terminal" in your applications menu or by pressing Ctrl + Alt + T.

  2. Update the Package List: It's a good practice to update your package list before installing new software to ensure you get the latest versions available. Run the following command:

  3. Install FFmpeg: Now, install ffmpeg by running:

  4. Verify the Installation: After installation, you can verify that ffmpeg is correctly installed by checking its version. This also confirms that ffmpeg is properly installed and accessible from your command line:

This command will show you the version of ffmpeg that was installed, along with some configuration details. With ffmpeg installed, you can now use it to perform video and audio conversion, streaming, recording, and more, directly from your Ubuntu terminal.

13

tell me about locate command

The locate command is a fast and efficient tool for finding the location of files and directories in Linux and Unix-like operating systems, including Ubuntu. It works by searching through a database that contains a snapshot of all the files on the system. Because it searches a database rather than scanning the filesystem in real-time, locate can find files much more quickly than tools like find that scan the filesystem directly.

Key Features of locate:

  • Speed: Searches with locate are generally faster than other searching methods that scan the filesystem in real-time because it queries an indexed database.

  • Simplicity: The command syntax is straightforward, making it easy to use for finding the path of files and directories.

How It Works:

  • locate uses a database created by updatedb. This database contains a list of files and directories located on the system. By default, updatedb runs periodically as a cron job to keep the database current, though it may not reflect very recent changes or additions until the next update.

  • When you use locate to search for a file, it looks through this database for matches and returns results that contain the search query.

Basic Usage:

To use locate, simply type locate followed by the name of the file or directory you're searching for:

This will return a list of paths where files or directories that match the name "filename" are located.

Examples:

  1. Find all instances of a file named example.txt:

  2. Limit the number of search results: You can limit the output to, say, the first 5 results using the -n option:

  3. Case insensitive search: By default, locate is case sensitive. Use the -i option for a case-insensitive search:

Updating the Database:

If you've recently added files to your system and want to ensure locate can find them, you may need to manually update the database. Do this with the updatedb command:

Installing locate:

If locate is not installed on your Ubuntu system, you can install it along with updatedb by installing the mlocate package:

After installation, the system will automatically create the initial database for locate to use. Remember, since locate relies on a periodically updated database, it might not find files that were added or removed since the last database update. For real-time searches, consider using find or similar tools, though they may be slower for extensive searches.

14

tell me about which command

The which command in Unix-like operating systems, including Ubuntu, is a simple yet powerful tool used to locate the executable file associated with a given command. When you type a command in the terminal, which searches through the directories listed in the PATH environment variable and shows the full path of the first executable file found that matches the command name you queried. This can be particularly helpful for determining which version of a program will be executed by default or for troubleshooting when multiple versions of the same program are installed.

Basic Usage

The basic syntax of the which command is:

Replace command_name with the name of the command you're investigating. For example:

This command will output the path to the Python interpreter that will be executed when you type python in the terminal, such as /usr/bin/python.

Features and Behavior

  • Searches $PATH: which only searches the directories listed in your shell's PATH environment variable. It doesn't search in directories that are not in PATH.

  • First Match: which stops searching after finding the first match. If there are multiple versions of a command in different directories listed in PATH, which will only show the one that would be executed when you type the command in the terminal, i.e., the first one found based on the order of directories in PATH.

  • Multiple Arguments: You can specify multiple command names to which, and it will locate each of them. For example:

  • Aliases and Functions: It's important to note that which may not always show aliases or shell functions since it does not execute commands within your shell. For bash users, the type command might be more useful for this purpose, as it can also identify aliases and functions.

Examples

  1. Find the path of the gcc compiler:

  2. Check whether a command is in PATH:

    If which does not return a path, it means the command is not found in the directories listed in your PATH or does not exist. This can be useful for checking whether a program is installed and accessible through PATH.

Installing which

On most Linux distributions, including Ubuntu, which is installed by default. If it's somehow missing, you can install it using the package manager. For Ubuntu or Debian-based systems:

The which command is a straightforward yet effective tool for finding executables in your system's PATH, aiding in software installation and configuration management.

15

How to change the jupyter lab default browser

Changing the default browser used by JupyterLab involves a couple of steps, as JupyterLab itself doesn't directly control which browser is launched. Instead, it uses the default browser setting from your operating system or the web browser environment variable. However, you can influence this behavior by setting an environment variable specifically for this purpose.

Method 1: Using an Environment Variable

You can specify a different browser for JupyterLab by setting the BROWSER environment variable before launching JupyterLab. This method works on Linux, macOS, and Windows. Here's how you can do it:

On Linux or macOS

  1. Open your terminal.

  2. Set the BROWSER environment variable. Replace /path/to/browser with the actual path to the browser executable you want to use. For example, if you want to use Firefox and it's located in /usr/bin/firefox, you would use:

  3. Run JupyterLab:

    This command tells the system to use Firefox (or whichever browser you specified) as the browser for JupyterLab sessions.

On Windows

  1. Open Command Prompt or PowerShell.

  2. Set the BROWSER environment variable. You need to provide the path to the browser executable you wish to use. For example, to set Google Chrome as your default browser for JupyterLab:

  3. Launch JupyterLab:

This method temporarily changes the default browser for JupyterLab sessions started in the current terminal session. To make the change permanent, you can add the export or set command to your shell's profile script (e.g., .bash_profile, .bashrc, or .zprofile for bash or zsh on Linux/macOS, or set it as a permanent environment variable on Windows).

Method 2: Configuring JupyterLab

Another approach involves using JupyterLab's configuration system to set the browser you want to use. You can specify the browser by setting the NotebookApp.browser configuration option in your Jupyter configuration file.

  1. Locate or create your Jupyter configuration file: If you don't already have a .jupyter/jupyter_notebook_config.py file in your home directory, you can generate one by running:

  2. Edit the configuration file: Open .jupyter/jupyter_notebook_config.py in your favorite text editor.

  3. Set the NotebookApp.browser option: Uncomment the line (if necessary) and set the value to the command that opens your desired browser. For example, to use Firefox:

    You might need to specify the full path to the browser executable, depending on your operating system and how it's configured.

  4. Save the file and restart JupyterLab.

These methods allow you to customize which web browser JupyterLab will open by default. If you encounter any issues, ensure the path to the browser executable is correct and that the browser is properly installed on your system.

16

Show linux distribution tree

Expanding on the initial tree, here's a more comprehensive view of the Linux distribution lineage, incorporating additional distributions and their derivatives:

This expanded tree includes some more branches under the major distributions, showcasing a wide variety of popular Linux distributions and their derivatives:

  • Debian and its derivatives like Ubuntu have a vast ecosystem with many specialized distributions focusing on different desktop environments, user experiences, and purposes (like Linux Mint for ease of use).

  • Slackware, one of the oldest distributions, has inspired distributions that focus on simplicity and modularity.

  • Redhat (RHEL) includes Fedora, which is a community-supported distribution that serves as a testing ground for the more stable RHEL. CentOS, which used to be a downstream project to rebuild RHEL from its source, has now shifted focus with CentOS Stream becoming a rolling-release distribution that lies between Fedora and RHEL in terms of its release cycle.

  • SUSE has both community-supported (OpenSUSE) and commercial (SLES) offerings, catering to different users from enthusiasts to enterprises.

  • Arch Linux is known for its rolling release model and has inspired distributions like Manjaro, which aims to be more user-friendly.

  • Gentoo is a source-based distribution, allowing users to optimize software for their hardware. It has derivatives like Funtoo, which is also source-based but with different optimizations and tools.

These relationships highlight the diversity within the Linux ecosystem, where distributions often share a common ancestry while diverging significantly in terms of goals, user experience, and target audiences.

17

Tops Linux Distros

Determining the "top" Linux distributions can vary based on the criteria used, such as popularity, ease of use, performance, stability, or specific use cases like servers, desktops, beginners, or advanced users. However, as of my last update in April 2023, some Linux distributions consistently rank highly across various metrics and user preferences:

1. Ubuntu

  • Target Audience: Desktop users, beginners, developers, and servers.

  • Why It's Popular: Ubuntu is renowned for its user-friendly interface, extensive hardware compatibility, and robust support community. It's also the basis for many other distributions, particularly those aimed at new Linux users.

2. Fedora

  • Target Audience: Developers and desktop users who prefer cutting-edge software.

  • Why It's Popular: Fedora is known for its innovation and close relationship with the upstream Linux community, often integrating the latest technologies before other distributions.

3. Debian

  • Target Audience: Desktop users, developers, and server administrators.

  • Why It's Popular: Debian is celebrated for its stability and vast software repositories. It's also the base for many other distributions, including Ubuntu and Raspberry Pi OS.

4. Arch Linux

  • Target Audience: Advanced users and those who prefer a rolling release model.

  • Why It's Popular: Arch allows users to build their system from the ground up, offering unparalleled customization. Its rolling release model ensures up-to-date software.

5. CentOS Stream (transition from CentOS Linux)

  • Target Audience: Servers and enterprise environments.

  • Why It's Popular: CentOS Stream provides a free, enterprise-grade Linux distribution that's closely aligned with Red Hat Enterprise Linux (RHEL), making it ideal for businesses and developers looking for a stable and secure operating system.

6. Manjaro

  • Target Audience: Users who want an Arch-based system but with an easier learning curve.

  • Why It's Popular: Manjaro offers the benefits of Arch Linux, including cutting-edge software and a rolling release model, but with more user-friendly defaults and easier installation.

7. openSUSE

  • Target Audience: Desktop users, developers, and server administrators.

  • Why It's Popular: openSUSE is known for its stability and scalability. It offers two releases: Leap for stability and Tumbleweed for the latest software in a rolling release.

8. Linux Mint

  • Target Audience: Beginners and desktop users looking for a Windows-like experience.

  • Why It's Popular: Linux Mint is based on Ubuntu and is known for its ease of use, elegant desktop environments, and inclusion of proprietary software that enhances the user experience.

9. Raspberry Pi OS (formerly Raspbian)

  • Target Audience: Raspberry Pi users.

  • Why It's Popular: Specifically designed for the Raspberry Pi hardware, it's the official operating system of the Raspberry Pi Foundation, optimized for educational and hobbyist projects.

10. Solus

  • Target Audience: Desktop users looking for a simple and elegant operating system.

  • Why It's Popular: Solus is an independent distribution known for its Budgie desktop environment and a focus on desktop usability.

These distributions cater to different kinds of users and use cases, from complete beginners to advanced users and from desktop systems to servers. Your choice should depend on your specific needs, preferences, and the kind of community support you're looking for.

18

set env in terminal

Setting an environment variable in the terminal can be done using different shell commands, depending on whether you want the change to be temporary (just for the current terminal session) or permanent (persisting across all future terminal sessions and reboots). Here's how to do both:

For Temporary Use

To set an environment variable for the duration of your current terminal session, you can use the export command in bash (the default shell in Ubuntu and many other Linux distributions), zsh, and similar shells. The syntax is:

For example, to set an environment variable named MY_VAR with the value HelloWorld, you would run:

This variable will be available for any program or script run from the current terminal session, but it will disappear once you close the terminal.

For Permanent Use

To permanently set an environment variable, so it persists across all sessions and reboots, you need to add the export command to a shell startup file.

For a Single User

  1. Open your user's shell profile file in a text editor. This file could be one of the following, depending on your shell and setup:

    • ~/.bashrc for bash

    • ~/.zshrc for zsh

    • ~/.profile or ~/.bash_profile can also be used in some environments

  2. Add the export line at the end of the file. For example:

  3. Save and close the file.

  4. To apply the changes without needing to log out and back in, source the file with one of the following commands (depending on which file you edited):

    or

For All Users

If you want to set an environment variable for all users on the system, you can edit /etc/environment or create a script in /etc/profile.d/.

  • Editing /etc/environment:

    1. Open /etc/environment in a text editor with root permissions.

    2. Add a line for the variable without the export keyword:

    3. Save and close the file. Changes will take effect after a reboot or re-login.

  • Creating a script in /etc/profile.d/:

    1. Create a new file with a .sh extension in /etc/profile.d/, such as myvars.sh, using a text editor with root permissions.

    2. Add an export line in this script:

    3. Make the script executable:

    4. Changes will take effect after a reboot or when a new shell session is started.

Setting environment variables is a powerful way to configure system behavior for your shell, scripts, and applications. Be cautious when setting variables globally to avoid conflicts or unexpected behavior in system-wide applications.

19

I have multiple conda environments. I need to know which env has specific library

To find out which of your Conda environments contains a specific library, you can use a combination of conda commands to list all your environments and then check each environment for the library. Here's a step-by-step guide on how to do this in the terminal:

1. List All Conda Environments

First, list all your Conda environments using:

or

This command will give you a list of all environments and their paths.

2. Check Each Environment for the Library

Next, for each environment listed, you can search for the specific library using the conda list command. You'll need to do this one environment at a time. The syntax is:

Replace env_name with the name of your environment and library_name with the name of the library you're searching for.

Automating the Process

If you have many environments and you want to automate this process, you can use a simple bash script to check each environment for the library. Here's an example script that searches for a library named example-lib:

Copy this script into a file, for example, search_conda_envs.sh, and then make it executable with:

Run the script by:

This script loops through all your Conda environments, checks each one for the presence of example-lib (or whichever library you're searching for), and prints out which environments contain the library.

Remember to replace "example-lib" with the actual name of the library you are searching for. This approach is useful if you're working with a large number of environments or need to frequently check for the presence of libraries across them.

20

top alternative to flameshot in ubuntu

Flameshot is a popular screenshot tool known for its ease of use and powerful features, including annotation capabilities. If you're looking for alternatives to Flameshot on Ubuntu, there are several other screenshot tools available that offer a variety of features. Here's a list of some top alternatives, each with its own set of functionalities:

  1. Shutter - Shutter is a feature-rich screenshot program that allows you to take screenshots of a specific area, window, your whole screen, or even of a website. It also provides an editing tool to annotate the screenshots. It's highly customizable and supports various plugins.

  2. Ksnip - Ksnip is a Qt-based cross-platform screenshot tool that provides many annotation features. It supports taking screenshots of a selected area, a specific window, and the entire screen. Ksnip also allows for editing screenshots with tools for annotating and highlighting.

  3. Spectacle - Spectacle is a straightforward screenshot utility primarily developed for KDE but can also be used in other desktop environments. It offers features for capturing the entire screen, a single window, or a custom rectangular area. It also supports delayed screenshots.

  4. Gnome Screenshot - If you're using the GNOME desktop environment, Gnome Screenshot is a simple and effective tool that comes built-in. It offers basic features for taking screenshots of your desktop, a window, or a selected area.

  5. ScreenCloud - ScreenCloud is an easy-to-use screenshot tool that emphasizes sharing. Apart from taking screenshots, it allows you to quickly share them through various cloud services or save them locally. It provides options for capturing the screen, a selected area, or a specific window.

  6. Scrot - Scrot is a lightweight, command-line-based screenshot tool. It's highly useful for users who prefer working in the terminal or need to automate their screenshot process through scripts.

  7. xfce4-screenshooter - This tool is part of the XFCE desktop environment but can be used in other environments as well. It provides features to capture the entire screen, a selected region, or a window and allows you to save or upload the screenshot directly.

Each of these tools offers a unique set of features that might suit different user needs, from basic screenshot capturing to more advanced needs like annotation and sharing. You can try them out and see which one best fits your requirements on Ubuntu.

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