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When you are working on a shell script in bash, there are cases where you want to check if a particular file exists (or does not exist) in a directory, and then perform an action based on the condition. In bash, there are several ways to check whether or a file exists in bash. This tutorial demonstrates bash shell script examples for this use case.

exFAT is a proprietary filesystem developed by Microsoft, and is commonly used for USB flash drive or SD cards. In order to mount an exFAT drive on Linux, you need to use exFAT FUSE or use kernel 5.4 or higher. This tutorial explains detailed procedures.

Amazon EC2 (Amazon Elastic Compute Cloud) is a part of AWS product offerings, where users can rent virtual servers in the AWS public cloud. You pay for rented compute resources (CPU, memory, hard drive) at per-second granularity on a "pay-as-you-go" basis. For those of you who have just started with Amazon EC2, this tutorial covers a step-by-step procedure to create a Linux instance on AWS EC2 platform.

A typical bootable USB drive or memory stick can only boot from a single ISO file stored on the drive, which is not only inconvenient but also wasteful for a large USB storage. This tutorial covers how to create a multi-ISO USB drive using an open-source tool called Ventoy.

It is certainly possible to find out the KVM VM's IP address without logging into the VM via console. Instructions vary depending on what type of guest networking is being used: NAT networking or bridged networking. This tutorial describes how to discover a VM's IP address in each of these cases.

WireGuard is an open-source VPN protocol implementation which is quickly gaining its popularity among VPN users due to its speed, ease-of-use and well-designed codebase. This tutorial focuses on setting up WireGuard VPN client by using a popular network management tool of choice: NetworkManager GUI.

WireGuard is a relatively new entrant in the VPN software scene, with a bold promise to dethrone OpenVPN from the top in terms of speed, ease of use, and auditability. This tutorial covers how to set up Wireguard VPN server on Ubuntu environment.

For various reasons you may want to know in how many lines of code given open-source software is implemented. For example, you want to estimate the effort devoted to developing a particular open-source program. Or you want to gauge the size and complexity of a program before trying it.

Looking to find out NetworkManager version for your Ubuntu and other Ubuntu releases? This tutorial can provide help with that.

In the past, close to 30K people signed up for a online petition, desperately wanting to have an official native Linux client for Google Drive, and yet their voice is still being ignored by Google. Perhaps when it comes to boosting their bottom line, Linux desktop market is not a priority for Google. If you want to mount Google Drive on Linux, you can try unofficial Linux software called google-drive-ocamlfuse (gdfuse), which is a FUSE-based file system backed by Google Drive.

For network interface card (NIC) hardware to operate properly, you need a suitable device driver for the NIC hardware. A NIC device driver implements a hardware-independent common interface between the Linux kernel and the NIC, so that packets can be moved between the kernel and the NIC. While some drivers may be statically built in the kernel, most drivers for modern NICs are dynamically loaded as kernel modules.

In some cases you may want to access shell environment variables (e.g., $PATH, $PWD, $HOME, $LANG) in your Perl script. While you can pass any needed variables to your Perl script via @ARGV argument array, this is actually not needed since Perl provides a way to access all available environment variables. Let's find out how to access shell environment variables in Perl script.

Intel Advanced Encryption Standard New Instructions (AES-NI) is a special instruction set for x86 processors, which is designed to accelerate the execution of AES algorithms. AES-based symmetric encryption is widely used in a variety of security applications and protocol implementations (e.g., IPSec, SSL/TLS, HTTPS, SSH). OpenSSL crypto library supports AES-based ciphers as well.

An RPM package contains a set of files, typically compiled software binaries, libraries, and their development source files. These files are packaged in a cpio archive format, and finally wrapped in an RPM file along with any necessary package-specific metadata.

Logging is an essential debugging feature for any programming and scripting language, which goes beyond simple print statements. For example, logging allows you to track in which module/function/linenumber logging messages are generated. You can also differentiate logging based on severity, and can direct logging messages to stdout/stderr, a file, a network socket, etc.

IP addresses (IPv4) are a scarce resource that is shared by different users and devices. Having an IP address conflict means that there are more than one network device or computer that claims the same IP address. IP address conflict may occur when a DHCP server has assigned an IP address to one computer, and the same IP address happens to be statically assigned to another network device by someone.

A bar graph is a plot which visualizes data values using proportional-size bars. Bar charts are useful when you want to compare multiple items among different categories. As you can imagine, they are much more effective than a table of numerical data.

An Ethernet bridge is a network component which interconnects multiple Ethernet networks by forwarding packets from one network to another. Linux has a software implementation of the Ethernet bridge (called "Linux bridge") incorporated into the kernel since 2.6. A Linux bridge is often used to set up a transparent proxy/firewall, or to work as a virtual switch which interconnects multiple virtual machines and containers created on a host.

If the default timezone of your Linux system is not correct, you need to correct it to get accurate local time. Note that configuring NTP is not a solution for an incorrect timezone as NTP itself does not handle timezones. NTP handles time data in UTC, and actual local time is calculated by adding the local time zone offset.

An .htaccess file is a directory-level configuration file for Apache HTTP server, which allows one to override the web server's system-wide settings without modifying the global configuration file (e.g., httpd.conf or apache2.conf). Things like per-directory access control, password protection, URL redirection or hot link prevention can be configured in the .htaccess file.