Week 2 Task – Advanced Log Report Automation - snir1551/DevOps-Linux GitHub Wiki

Week 2 Task – Advanced Log Report Automation

🧠 Task Overview

Develop a Bash script that:

Accepts a log directory path
Accepts one or more keywords to search for
Counts keyword occurrences in .log files
Generates reports in both .txt and .csv formats
Supports both interactive and argument-based usage

✅ CLI Options

Flag	Description
--keywords	Space-separated list of keywords to search in .log files
--logdir	Directory containing the log files
--interactive	Run in interactive mode (ask for directory & keywords)
--help	Show help message

📄 Output

report.txt – Human-readable report in tabular format
report.csv – CSV file for spreadsheet or script integration

🐚 Bash Script Commands Reference

This document provides a categorized reference of Bash commands, operators, and syntax elements used in the script.

🧠 General Bash Concepts

Command	Description
`#!/bin/bash`	Declares that the script is written for the Bash shell.
`function name() { ... }`	Defines a reusable block of code (function).
`local file`	Declares a local variable named `file` that is only accessible within the current function.
`exit 1`	Stops the script with an error status (non-zero).

📥 Arguments and Parameters

Command	Description
`$0`	Represents the name of the script or function being executed.
`$1`	Refers to the first positional argument passed to the script or function.
`$#`	Represents the number of positional arguments passed to a script or function.
`"$@"`	Represents all arguments passed to the script.

🔁 Loops and Conditions

Command	Description
`if [ condition ]; then ... fi`	Basic conditional structure used to execute code based on a condition.
`while read -r file; do ... done`	Loops over each line or file passed through the pipe safely.
`for var in list; do ... done`	Loops over each item in a list or array and performs commands for each.
`case "$1" in ...)`	Used to handle multiple options or flags like `--help`, `--logdir`, etc.
`if [ ! -d "$LOG_DIR" ]`	Checks if the directory in `LOG_DIR` does not exist.

🧮 Arithmetic Operators

Command	Description
`-eq`	Returns true if two numbers are equal.
`-ne`	Returns true if two numbers are not equal.
`-gt`	Returns true if the first number is greater than the second.
`-lt`	Returns true if the first number is less than the second.
`-ge`	Returns true if the first number is greater than or equal to the second.
`-le`	Returns true if the first number is less than or equal to the second.
`$(( expression ))`	Performs arithmetic operations like addition, subtraction, etc.

📋 Variables and Arrays

Command	Description
`KEYWORDS=()`	Initializes an empty array called `KEYWORDS`.
`KEYWORDS=(ERROR WARNING CRITICAL)`	Declares an array with values.
`KEYWORDS[@]`	Expands to all elements of the array (each element quoted separately).
`KEYWORDS[*]`	Expands to all elements as a single word (joined by IFS).
`${#ARRAY[@]}`	Returns the number of elements in an array.

⌨️ Input

Command	Description
`read -p "..." VAR`	Prompts the user for input and stores it in `VAR`.
`read -a ARRAY`	Reads multiple words into an array.

🖨️ Output and Formatting

Command	Description
`echo` / `echo "text"`	Prints text or variables to the terminal.
`printf`	Formats and prints text with fine control (padding, precision, etc.).
`%-10s`	A `printf` format specifier: left-aligns string in a 10-character width.

📁 Files and Redirection

Command	Description
`>`	Overwrites a file with new content.
`>>`	Appends output to a file without overwriting.

🔍 File Searching & Reading

Command	Description
`find`	Searches files and directories recursively.
`find DIR -type f -name "*.log"`	Finds all `.log` files inside `DIR` and its subdirectories.

🔎 Text Processing

Command	Description
`grep -o`	Prints only the matched parts of each line.
`grep -o "word" file`	Finds and prints each match of `"word"` in the file, one per line.
`wc -l`	Counts the number of lines in input. Often used to count matches.
`sed`	A stream editor used to perform basic text transformations on input. Example: `sed 's/old/new/'` replaces the first occurrence of `old` with `new`.
`awk`	A powerful text-processing tool. Example: `awk '{ print $1 }'` prints the first word of each line.

⏱️ Time & Date

Command	Description
`date`	Displays the current date and time.
`date +%s`	Returns the current time in seconds since epoch (used for timing).
`date +%s.%N`	Returns time in seconds with nanosecond precision.
`date +"%Y-%m-%d %H:%M:%S.%3N"`	Prints the full date and time with milliseconds.