What Ports Need to be Opened for NTPD?
By default, NTPD uses UDP port 123 for NTP servers and 1023 port for NTP clients. These ports need to open to allow incoming NTP traffic.
What Does ‘sudo rm -rf /*’ do?
The “sudo rm -rf /*” command recursively deletes all files and directories from the root directory. It deletes all the files on the computer permanently.
How to Output the Binary Representation of a Hex Number Using xxd Command?
To output the binary representation of a hex number, execute the “echo -n “
![What Does_^[0-9]+$_ Mean in Bash](https://itslinuxfoss.com/wp-content/uploads/2023/03/What-Does_^0-9_-Mean-in-Bash-01.webp)
What Does ‘^[0-9]+$’ Mean in Bash?
In Bash, the regular expression ‘^[0-9]+$’ matches a string that contains only one or more digits (0-9) and no other characters.
How to Set the Default Gateway in Ubuntu?
To set the default gateway in Ubuntu, execute the “sudo ip route add default via
Python Regex Capturing Groups
Python regex capturing groups enable you to capture specific parts of a string based on a specified pattern such as using (\b\d+) pattern for capturing digits.
Valueerror: Setting an Array Element With a Sequence
This value error occurs due to various reasons such as creating an array with different dimensions, replacing a single array element with an array, etc.
How to Convert Pandas Series to a DataFrame?
To convert the Pandas series to a DataFrame the “pd.DataFrame()” function and “series.to_frame()” function is used in Python.
How to Reattach to an Existing “screen” Session?
To reattach an existing screen session, use the “screen” tool followed by the “-r(reattach)” argument and the “SID” or the “specific session name”.
How to Update NodeJS Version in Ubuntu Command Line?
To update the NodeJS versions in Ubuntu, use the “NVM(Node Version Manager)”, “NPM(Node Package Manager)”, and “Binary Packages”.
What is gdm3, kdm, lightdm? How to Install and Remove them on Ubuntu?
gdm3, kdm, and lightdm are display managers of Linux that provide the interface for the login screen and can be installed or uninstalled.
How to Instant Search in less Command?
To instant search with the “less” command, use the “less
How to Install the Latest Python on CentOS?
To install the latest version of Python on CentOS, use the YUM package manager, and source code that is given on the official Python website.
How to Extract Dictionary Values as a List?
To extract dictionary values as a list, the “list()” function, “list comprehension”, “for loop”, “* operator”, and “map() function” is used in Python.
[Fixed] “Hostname: Name or Service not Known” Error?
The error is caused when the user tries to change the hostname, which is not found in the /etc/hosts file, and it is fixed by adding the hostname to that file.
What is the Significance of the “wheel” Group in Ubuntu?
In Ubuntu, the “wheel” group is a special user group that provides administrative access to certain users on a system to perform administrative tasks.
What Does “cp: omitting directory” Mean?
In Linux, the error “cp: omitting directory” represents that the “cp” command expects a file as the source, not a directory.
How to Python Check Version of Package With pip?
To check the version of the package with pip, the “pip show
Why Does Find -mtime +1 Only Return Files Older Than 2 Days?
The find -mtime +1 only returns files older than two days because it only returns the files modified in the last two or less than two days.
How to Export a GPG Private Key and Public Key to a File?
To export a GPG private and public key, use the “gpg –export-secret-key -a
How to Add a DNS Server Via resolv.conf?
To add a DNS server via resolv.conf configuration file, add a nameserver directive followed by the IP address of the DNS server.
How to Capture All the UDP Packets Using tcpdump?
To capture all the UDP packets using the tcpdump command, execute the “sudo tcpdump -i
How to Step Into, Step-over, and Step-out With GDB?
To step into, step over, and step out with GDB, use the “step”, “next”, and “finish” commands. These GDB commands quickly identify and fix bugs in the program.
Where are Apache File Access Logs Stored in Ubuntu?
In Ubuntu, the Apache access log files are stored in the “/var/log/apache2” directory. These files contain details of all the requests made to the web server.
How to Install and Run a TFTP Server?
To install and run the TFTP server, execute the “sudo apt install tftpd-hpa” command and configure the “tftpd-hpa” configuration file.
How to Give Full Permission to Folder and Subfolder?
To give full permission to a folder and its subfolders, use the “chmod 777
How to Force a Clock Update Using NTP?
To force a clock update using the NTP server, use the “ntpdate” command and “ntpd” service. They synchronize the time on the system with the time NTP server.
How to Upgrade Java on Ubuntu?
To upgrade Java on Ubuntu, use the “sudo apt install openjdk-19-jdk” command or download the latest version of Java from the Oracle website and install it.
How do I Find Out Users in a Group?
To find out which users are in a group within Linux, utilize the “groups”, “getent”, and “id -Gn” commands and the “/etc/group” file.
How Does Reverse SSH Tunneling Work?
To reverse SSH tunneling connection, execute the “ssh -R
Difference Between cp -r and cp -a in Linux
The difference between cp -r and cp -a is that cp -a preserves all file attributes, while cp -r only preserves the ownership and permissions of the files.
How to Start/Stop MySQL Server on Ubuntu?
To start and stop the MySQL server on ubuntu, execute the “sudo systemctl start mysql” and “sudo systemctl stop mysql” commands.
How to Make ZSH the Default Shell in Ubuntu?
To make ZSH the default shell in Ubuntu, use the “chsh -s $(which zsh)” or “sudo usermod -s /usr/bin/zsh
How to Run the SSH Server on a Port Other Than 22?
To run the SSH server on a port other than 22 is possible by changing the port number in the “sshd_config” configuration file
How to Get File Created/Creation Time in Linux?
To get the file created/creation time in Linux, use the “stat”, “debugfs”, “ls” commands, and “Properties” options in GUI.
How to Completely Uninstall Docker?
While uninstalling docker, a few configuration files and components must be manually deleted through a series of commands which require execution one by one.
How to Reduce a Video Size With FFmpeg?
Sharing large videos takes a lot of time, so FFmpeg is used to manipulate videos, change resolutions, and trim so that the size is reduced.
How to Use SCP with PEM File?
To create a “.pem” file using the SCP, use the “ssh-keygen -f ~/.ssh/id_rsa -e -m pem” command. Then, upload or download a file or directory using SCP.
How to Move Files or Directories in Python?
To move files or directories, the “shutil.move()” function, “os.rename()” method, and “pathlib.path()” function is used in Python.
How to Install PIL/Pillow Using PIP?
To install PIL/Pillow, the “pip” package manager is used in Windows, Linux, and MacOS. The “pip install pillow” command is used to install the module.
How to Check Your TensorFlow Version in Colab?
To check your TensorFlow version in Colab, import the TensorFlow library and print the installed version using the “__version__” attributes.
How to Uninstall a Package in Python Using PIP?
To uninstall a package in Python using the “pip” package manager, you need to execute the “pip uninstall
String Equals Check in Python
To check or compare the strings’ equality, the “is” operator, “==” operator, “‘!=” operator, and “ __eq__()” function is used in Python.
How to Fix Disk Quota Exceeded in Linux?
When a user exceeds the assigned disk quota, it causes “Disk Quota Exceeded,” which is fixed by freeing the disk space or getting more quota.
What is the Difference Between $@ and $* in Bash?
In Bash, the main difference between $@ and $* is that “$@” preserves the individual arguments as separate words, while other preserves them as a single string.
KDE vs GNOME | Everything You Need to Know
Explore the differences between KDE and Gnome, two popular desktop environments for Linux. Decide which one is right for you.
How Can I Force wget to Use a Proxy Server Without Modifying System Files?
To forcefully use wget for a proxy server without modifying system files, set “http_proxy” and “https_proxy” variables with server address and port.
What Does “ps -ef | grep processname” Command Mean in Linux?
The “ps -ef | grep processname” command filters out a process from a list of running processes and displays information in the Linux system.
Where are All the Major Log Files Located in Ubuntu?
In Ubuntu, major log files are located in the “/var/log” directory. It includes “sys.log”, “auth.log”, and “kern.log” log files.
How to Get a List of All Scheduled Cron Jobs on a Machine?
Linux offers the “crontab -l” command to get a list of all scheduled cron jobs. It displays jobs on the basis of monthly, weekly, daily, and hourly.
How to Get a List of all Installed Repositories PPAs on Ubuntu?
To get a list of all installed PPA repositories, utilize the “apt policy” command, “Software & Updates” utility, and “/etc/apt/sources.list” file.
How to Let dpkg Install Dependencies Automatically?
To install dependencies automatically with the dpkg package manager, users can execute the “sudo apt install -f” command in the terminal.
How to Unzip .tgz File Using the Terminal?
To unzip the “.tgz” file in the Linux terminal, utilize the “tar”, and “gunzip”, commands. They required the zip file to have the “.tgz” extension.
How to Generate a Random String in Linux?
To generate random strings in Linux, use the “Random Number Generator”, “OpenSSL library”, “UUID generator”, and “mktemp” commands.
How to Upgrade Docker on Ubuntu?
To upgrade Docker on Ubuntu, first, uninstall Docker’s old version. Then, download and install the latest Docker package from the official Docker repository.
Python foreach Loop
The “for-in” expression, “list comprehension” and “map()” function is used to perform the “foreach” loop on every element of the given iterator in Python.
Python JSON Parsing Using json.load() and loads()
The “json.load()” and “json.loads()” functions are used to parse JSON data in Python objects such as dictionaries, lists, etc.
Python DateTime Format Using strftime()
The “strftime()” function is used to represent the DateTime in string format based on the specific standard directives/character codes.
How to Create a Correlation Matrix Using Pandas?
The “df.corr()”, “sn.heatmap()”, and “plt.show()” functions are used to create, represent, and plot correlation matrix in Python.
How to Convert a List to a NumPy Array?
To convert a list or list of lists to a Numpy array the “numpy.array()” function and the “numpy.asarray()” function is used in Python.
How to Convert a JSON String to CSV Using Python?
To convert the JSON string to CSV the “pd.read_json()” and “df.to_csv()” functions of the Pandas module are used in Python.
How do I Uninstall MySQL in Ubuntu?
To uninstall MySQL in Ubuntu, remove the “mysql-server”, “mysql-client” and “mysql-common” packages from the operating system.
How to install .run files?
In Linux, all the “.run” files can be installed by using the “chmod” command and the “Permissions” options to make them executable.
What Does “chmod +x ” do and How to Use it?
The “chmod +x” command modifies the file permissions and makes it executable. Also, make multiple files executables via the “chmod +x
How to Change Password in Linux? Root User and User Account
To change the password on the root user and user account in Linux, execute the “sudo passwd root” and “sudo passwd
How to Set Date Through Command Line in Linux?
To set the date through the command line, utilize the “date”, “hwclock”, “timedatectl” and “ntpdate” commands by specifying the “YYYY-MM-DD hh:mm:ss” format.
What Does “export PATH=something:$PATH” Mean in Linux?
The “export PATH=something:$PATH” command changes the “PATH” environment variable of the current system by specifying the path in the “something” variable.
How to Find All Large Files in the Root Filesystem in Linux?
To find all large files in the root filesystem, you can utilize the “find”, “du”, and “ncdu” commands. Also, you can specify the size limit, and sorting order.
How to See Full Log From systemctl status service?
To see the full log from systemctl status services, execute the “systemctl status service_name -l” command in the system.
What is the “eval” Command in Bash?
In Bash, the “eval” command evaluates its arguments as a shell script including “commands”, “variables”, “arithmetic expressions”, and “strings”.