When to Use Globs vs Regular Expressions Glob patterns, also known as wildcards, are a simple pattern matching syntax used to match file and directory names in Linux and other Unix-like operating systems. Regular expressions are a more advanced way of defining search patterns that support a wider range of matching capabilities. Globs excel at…
The POSIX (Portable Operating System Interface) standards specify several flavors of regular expressions used in programming languages and text processing. This article will explore the history, core syntax, and key features of basic POSIX regular expressions, extended POSIX regular expressions, and Perl-compatible regular expressions (PCRE). History of POSIX and regex standards The Institute of Electrical…
Regex Engines Vary Across Distros Regular expressions (regexes) are widely used in Linux for text processing and validation. However, different Linux distributions use different regular expression engines by default. Some popular engines include PCRE (Perl Compatible Regular Expressions), Oniguruma, and POSIX Basic Regular Expressions (BRE). PCRE is a full-featured regex engine that provides advanced capabilities…
A regular expression (regex or regexp for short) is a sequence of characters that defines a search pattern. Regexes provide a concise and flexible means for matching strings of text, such as particular characters, words, or patterns of characters. They are supported by many text editors and programming languages to find and manipulate text based…
Selecting a High-Performance Linux Distribution Choosing the right Linux distribution is key to achieving optimal performance on modern computers. Popular options like Ubuntu, Fedora and Arch Linux offer advantages for speed and responsiveness. Ubuntu Ubuntu utilizes the Debian-based APT package manager, providing access to thousands of optimized software packages. Canonical, the company behind Ubuntu, focuses…
Assessing Your System’s Vulnerabilities Conducting a thorough assessment of potential vulnerabilities is a critical first step towards securing a Linux system. Unpatched flaws in the operating system, misconfigured services, and unnecessary packages can all introduce weaknesses that could be exploited by an attacker. Scanning for Known Vulnerabilities with Tools like Lynis and OpenSCAP Vulnerability scanners…
The Risks of Editing Live Data Editing live data on Unix systems without proper precautions carries significant risks of data loss or corruption. Critical system files and databases often do not have built-in protection against manual editing errors. A single mistaken keystroke can permanently destroy data or cause system instability. Examples of potential issues include:…
Harnessing Shell Redirection for Automation What Problem Do Redirections Solve? The standard Unix shell provides three default data streams – standard input, standard output, and standard error. Programs typically receive data via standard input, emit results to standard output, and log errors to standard error. This linear execution flow limits the ability to chain together…
Mitigating the Risks of Unsecure Shell Scripts Shell scripts provide a convenient way to automate tasks on Linux and Unix-based systems. However, unsecure shell scripts can expose systems to significant risks. Flaws in shell scripts may enable arbitrary code execution, allowing attackers to execute malicious commands and take control of systems. Arbitrary code execution through…
The Risks of Unchecked User Input in Shell Scripts Shell scripts can execute system commands via user input without proper validation. This allows attackers to inject additional malicious commands giving them unauthorized system access. Potential damages include sensitive data theft, malware installation, and container escape. Shell scripts use interpretation to execute commands from user input….