Command-Line Case Studies

Introduction

This lesson explores various command-line case studies that demonstrate practical applications of shell scripting and command-line tools in Linux for system administration. Each case study highlights specific tasks that can be automated to improve efficiency and effectiveness.

Case Study 1: Batch File Renaming

In this case study, we will demonstrate how to rename multiple files in a directory using a Bash script.

#!/bin/bash
# Rename files to have a .bak extension

for file in *.txt; do
    mv "$file" "${file%.txt}.bak"
done

This script iterates over all .txt files in the current directory and renames them to have a .bak extension.

Case Study 2: Log File Analysis

Let's analyze a log file to extract entries from a specific date.

grep '2023-10-01' /var/log/syslog > extracted_logs.txt

This command uses grep to search for entries containing the date 2023-10-01 in the syslog file and outputs the results to extracted_logs.txt.

Case Study 3: System Monitoring

This case study demonstrates how to monitor system resource usage over time using a shell script.

#!/bin/bash
# Monitor CPU and memory usage

while true; do
    date >> usage.log
    top -bn1 | grep "Cpu(s)" >> usage.log
    free -m >> usage.log
    sleep 60
done

This script logs CPU and memory usage every minute into usage.log.

Best Practices

When using command-line tools and scripts, consider the following best practices:

Always back up important data before running scripts that modify files.
Use version control for your scripts to track changes.
Comment your scripts for clarity and maintainability.
Test scripts in a safe environment before deploying them in production.

FAQ

What is a shell script?

A shell script is a text file containing a series of commands that can be executed by the shell (command-line interpreter). It can automate tasks and streamline processes.

How do I execute a shell script?

You can execute a shell script by navigating to its directory and running ./scriptname.sh after making it executable with chmod +x scriptname.sh.

What tools are commonly used in command-line case studies?

Common tools include bash, grep, awk, sed, and various system monitoring commands like top.