The Backslash Escaping Problem in Awk Awk is a popular text processing language in Linux and UNIX systems. It is commonly used to parse and manipulate text files and output streams. Awk scripts often work closely with shell scripts to process shell variables and command outputs. A major issue arises when passing shell variables containing…
Escaping Tricky Characters Using the shell to execute commands and scripts requires properly dealing with spaces, quotes, and special characters. Characters like spaces, asterisks, and parentheses have special meaning in bash and other shells. Without escaping or quoting them correctly, the shell may interpret them incorrectly leading to errors or unexpected behavior. Why spaces and…
What Triggers the Shebang Line The shebang line, written as #! on the first line of executable scripts, indicates the interpreter that should execute the script. This directive tells the operating system to use the specified program to handle the script instead of trying to execute it directly. The shebang line ultimately triggers the corresponding…
What is the Shebang? The shebang refers to the two characters “#!” that start interpreter directive lines in Linux and other Unix-like operating systems. Acting as a marker, the shebang indicates to the system which interpreter should be used to execute the script that follows. Definition of the shebang The term “shebang” is derived from…
What is Reserved Space and Why Does it Matter? Reserved filesystem space refers to the percentage of total disk space that is kept unused and allocated for root users only. This space cannot be used by regular users or processes and serves a vital purpose. Having sufficient reserved space enables critical system functions and emergency…
What is Reserved Space for Root? The reserved space for root in a Linux filesystem refers to the percentage of total disk space that is set aside for use exclusively by the root user and other essential system processes. By default, most Linux distributions set aside 5% of the total disk space as reserved space…
Securing Accounts and Passwords Implementing strong password policies is a critical first step towards securing Linux and Unix systems. Short, simple, or default passwords provide easy targets for attackers to gain initial access. Here are some best practices for enhancing password security: Enforce password complexity requirements through modules like pam_cracklib. This ensures passwords have a…
Enabling Kernel Features for Cloud Workloads The Linux and Unix-like kernels offer advanced control group (cgroup) functionality for limiting, prioritizing, accounting for, and isolating CPU, memory, disk I/O, network, and other resources for workloads. Configuring cgroups allows setting resource limits, guarantees resource minimums, divides resources proportionally, and defines hard and soft caps per workload. Namespaces…
Understanding Containers and Virtual Machines Containers and virtual machines are two virtualization technologies that allow multiple workloads to run on a single Linux or Unix-like host. Containers virtualize at the operating system level by isolating processes and resources using features like namespaces and cgroups in the Linux kernel. This allows running multiple isolated container instances…
Kernel Networking Subsystems The Linux and Unix networking stack consists of several key components in the kernel that handle the sending, receiving, forwarding, and routing of network packets. Optimizing the performance of these subsystems is critical for achieving high throughput and low latency network communication. TCP/IP Stack The Linux TCP/IP stack implements core protocols like…