Freaks City

Positional Parameters Positional parameters allow scripts to accept command-line arguments: $0 - Name of the currently executing script $n - nth argument passed to the script (use braces for n > 10, e.g., ${10}) $# - Number of arguments passed to the script $* - All arguments as a single string $@ - All arguments as separate string ...

Arithmetic Operations Script files must begin with #!/bin/bash. Comment are denoted by #. Code should be properly indented with whitespace. Arithmetic operations support: +, -, *, /, **, %. Evaluation methods: # Method 1 let VAR=arithmetic-expression # Method 2 VAR=$[arithmetic-expression] # Method 3 VAR=$((arithmetic-expression)) # Method 4 ...

Script Structure and Execution Shell scripts require a shebang line at the beginning to specify the interpreter: #!/bin/bash #!/usr/bin/python3 Comments use the # symbol and are single-line only. To execute a script: chmod +x script.sh ./script.sh Input and Output Reading input with read: read input_var read -p "Enter value: " pro ...

Generating SSH Key Pairs Initialize secure authentication by creating an RSA key pair on the management node. The following command generates the keys without a passphrase for automation purposes. ssh-keygen -t rsa -b 2048 -f ~/.ssh/id_rsa -N "" Non-Interactive Authentication Setup To facilitate scripted connections where manual pass ...

Understanding the Stream Editor (sed) The Stream Editor (sed) is a powerful utility in Unix/Linux systems for processing text files. It allows you to perform complex text manipulation operations using simple commands. This guide explores the fundamental operations of sed including deletion, insertion, and modification. Basic Setup Before workin ...

CPU Utilization Threshold Alert Monitor processor load and trigger a notification when usage exceeds a defined limit. This implementation calculates active CPU time by subtracting the idle percentage reported by top. #!/usr/bin/env bash ALERT_LIMIT=75 CURRENT_LOAD=$(top -bn1 | awk '/^%Cpu/ {print 100 - $8}') if awk "BEGIN {exit !($CURR ...

Obtaining sub-second precision in Linux environments requires leveraging either shell built-ins or external libraries. The GNU date command supports nanosecond resolution via the %N directive, while Python’s standard library offers flexible multipliers for milliseconds or microseconds. # Capture current timestamp with nanosecond precision NANO_ ...

Executing Shell Programs Scripts are invoked by specifying the interpreter or making them executable. The standard approach involves passing arguments directly to the program. #!/bin/bash ./automation_runner.sh --verbose flag-one Quoting and Substitution Mechanics Proper handling of strings prevents unexpected parsing errors. Backticks: Legac ...