# 5 Useful Bash Scripts for Everyday Tasks

**5 Useful Bash Scripts for Everyday Tasks**

**Objectives:**

* Learn to write and understand practical Bash scripts for common automation tasks.
* Develop scripts that interact with files, directories, logs, and system information.
* Apply error handling, input validation, and logging to these scripts.

***

#### **Chapter Outline:**

#### **1. Disk Usage Report**

**Script Overview:**

This script generates a detailed disk usage report for the user, highlighting space usage by directories.

```bash
#!/bin/bash

# Check if directory path is provided
if [ -z "$1" ]; then
    echo "Usage: $0 <directory_path>"
    exit 1
fi

directory="$1"

# Check if the directory exists
if [ ! -d "$directory" ]; then
    echo "Directory not found: $directory"
    exit 1
fi

# Display disk usage report
du -sh "$directory"/* | sort -rh > disk_usage_report.txt
echo "Disk usage report saved to disk_usage_report.txt"
```

[**https://github.com/bc0de0/bash-scripts/blob/master/disc\_usage.sh**](https://github.com/bc0de0/bash-scripts/blob/master/disc_usage.sh)

**Explanation:**

1. **Argument Validation:**
   * Checks if the user provides a directory argument.
   * Verifies if the directory exists.
2. **Disk Usage Report:**
   * The `du -sh` command displays the disk usage of all items in the directory, and the result is sorted by size (`sort -rh`).
3. **Output to File:**
   * The report is saved as `disk_usage_report.txt`.

**Real-World Use:**

This script can be used to monitor disk space usage and identify large files that need cleaning.

***

#### **2. Monitoring Active Network Connections**

**Script Overview:**

A script that monitors active network connections and logs them to a file for later analysis.

```bash
#!/bin/bash

log_file="network_connections.log"

# Capture active network connections using netstat
echo "Active network connections:" >> "$log_file"
netstat -tunapl >> "$log_file"
echo "Captured at: $(date)" >> "$log_file"
echo "----------------------------" >> "$log_file"

echo "Network connections logged to $log_file"
```

[**https://github.com/bc0de0/bash-scripts/blob/master/net\_chk.sh**](https://github.com/bc0de0/bash-scripts/blob/master/net_chk.sh)

**Explanation:**

1. **`netstat` Command:**
   * `netstat -tunapl` shows active network connections along with their listening ports (`t` for TCP, `u` for UDP, `n` for numeric IPs, `a` for all connections, `p` for programs).
2. **Logging:**
   * The output of `netstat` is appended to `network_connections.log`, which includes a timestamp (`$(date)`).

**Real-World Use:**

This is useful for monitoring network activity, detecting potential intrusions, or identifying suspicious connections.

***

#### **3. Automated Backup of Log Files**

**Script Overview:**

A script to automate the backup of system log files.

```bash
#!/bin/bash

# Define source and backup directories
log_dir="/var/log"
backup_dir="/backup/logs"
timestamp=$(date +"%Y%m%d_%H%M%S")

# Check if backup directory exists, if not create it
if [ ! -d "$backup_dir" ]; then
    mkdir -p "$backup_dir"
fi

# Archive and compress log files
tar -czf "$backup_dir/log_backup_$timestamp.tar.gz" -C "$log_dir" .

echo "Log backup completed: log_backup_$timestamp.tar.gz"
```

[**https://github.com/bc0de0/bash-scripts/blob/master/log\_backup.sh**](https://github.com/bc0de0/bash-scripts/blob/master/log_backup.sh)

**Explanation:**

1. **Directory Setup:**
   * Checks if the backup directory exists; if not, it creates it.
2. **Backup and Compression:**
   * Uses `tar` to archive and compress the log files into a `.tar.gz` file, saved with a timestamp for easy identification.

**Real-World Use:**

This script automates the backup of log files, ensuring important logs are archived regularly for auditing or forensic analysis.

***

#### **4. Find and Kill Resource-Heavy Processes**

**Script Overview:**

A script to find processes consuming too much CPU or memory and prompt the user to kill them.

```bash
#!/bin/bash

# Display top 5 CPU-consuming processes
echo "Top 5 CPU-consuming processes:"
ps -eo pid,comm,%cpu --sort=-%cpu | head -n 6

# Ask user if they want to kill any process
read -p "Enter the PID of the process to kill (or press Enter to skip): " pid

# If the user provided a PID, kill the process
if [ -n "$pid" ]; then
    kill -9 "$pid"
    echo "Process $pid killed."
else
    echo "No process killed."
fi
```

[**https://github.com/bc0de0/bash-scripts/blob/master/proc\_kill.sh**](https://github.com/bc0de0/bash-scripts/blob/master/proc_kill.sh)

**Explanation:**

1. **Display Top CPU-Consuming Processes:**
   * `ps -eo pid,comm,%cpu` lists processes along with their PID, command name, and CPU usage, sorted by CPU usage.
2. **User Input:**
   * Prompts the user to decide whether to kill a resource-heavy process.
3. **Kill Process:**
   * If a PID is provided, the script kills that process using `kill -9`.

**Real-World Use:**

This script helps system administrators manage server resources by identifying and terminating processes that consume excessive CPU or memory.

***

#### **5. Automated System Health Check**

**Script Overview:**

A script that checks system health by gathering key system information and logs it.

```bash
#!/bin/bash

log_file="system_health_check.log"

# System uptime
echo "System Uptime:" >> "$log_file"
uptime >> "$log_file"
echo "----------------------------" >> "$log_file"

# Memory usage
echo "Memory Usage:" >> "$log_file"
free -h >> "$log_file"
echo "----------------------------" >> "$log_file"

# Disk usage
echo "Disk Usage:" >> "$log_file"
df -h >> "$log_file"
echo "----------------------------" >> "$log_file"

# Top 5 processes by CPU usage
echo "Top 5 CPU-consuming processes:" >> "$log_file"
ps -eo pid,comm,%cpu --sort=-%cpu | head -n 6 >> "$log_file"
echo "----------------------------" >> "$log_file"

echo "System health check logged to $log_file"
```

[**https://github.com/bc0de0/bash-scripts/blob/master/sys\_health.sh**](https://github.com/bc0de0/bash-scripts/blob/master/sys_health.sh)

**Explanation:**

1. **System Information:**
   * The script gathers uptime, memory usage (`free -h`), and disk usage (`df -h`).
2. **CPU Processes:**
   * Captures the top 5 CPU-consuming processes.
3. **Logging:**
   * All the gathered information is logged in a file for future reference.

**Real-World Use:**

This script is useful for performing quick system health checks, making it easier to monitor resource utilization on servers or workstations.

***

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