This script gathers essential server metrics, including the hostname, network details, OS version, kernel data, CPU specifications, and memory capacity. It utilizes color codes to improve output readability.

#!/bin/bash
# Filename: server_status.sh

# Define color variables for terminal output
COLOR_RESET='\033[0m'
COLOR_HEADER='\033[1;36m'
COLOR_INFO='\033[1;33m'

# Print header
echo -e "${COLOR_HEADER}========== Server System Status ==========${COLOR_RESET}"

# Retrieve Hostname
echo -e "Hostname:       ${COLOR_INFO}$(hostname)${COLOR_RESET}"

# Retrieve IP Address (get primary IP via ip route)
CURRENT_IP=$(ip route get 1 | sed -n 's/^.*src \([0-9.]*\) .*$/\1/p')
echo -e "IP Address:     ${COLOR_INFO}${CURRENT_IP}${COLOR_RESET}"

# Retrieve OS Version
echo -e "OS Version:     ${COLOR_INFO}$(cat /etc/os-release | grep PRETTY_NAME | cut -d '"' -f 2)${COLOR_RESET}"

# Retrieve Kernel Version
echo -e "Kernel Version: ${COLOR_INFO}$(uname -r)${COLOR_RESET}"

# Retrieve CPU Model
echo -e "CPU Model:      ${COLOR_INFO}$(lscpu | grep 'Model name' | awk -F: '{print $2}' | xargs)${COLOR_RESET}"

# Retrieve Total Memory
echo -e "Total Memory:   ${COLOR_INFO}$(free -h | awk '/^Mem:/ {print $2}')${COLOR_RESET}"

# Retrieve Disk Usage for main drives
echo -e "Disk Space:     ${COLOR_INFO}$(df -h | grep '^/dev/sd' | awk '{print $1 ": " $5}')${COLOR_RESET}"

echo -e "${COLOR_HEADER}===========================================${COLOR_RESET}"

Execution Tip: Use bash -n script_name.sh to check for syntax errors and bash -x script_name.sh to debug the execution logic.

2. Automated Directory Backup

The following script creates a daily backup of the system configuration directory. It organizes backups by date stamp in a designated repository.

#!/bin/bash
# Filename: daily_backup.sh

LOG_COLOR='\033[1;35m'
RESET='\033[0m'
BACKUP_ROOT="/data/backups"
SOURCE_DIR="/etc"
TODAY=$(date +%Y-%m-%d)

echo -e "${LOG_COLOR}Initiating backup sequence...${RESET}"
sleep 1

# Create backup directory if missing
[ ! -d "$BACKUP_ROOT" ] && mkdir -p "$BACKUP_ROOT"

# Perform the copy operation
cp -r "$SOURCE_DIR" "${BACKUP_ROOT}/config_${TODAY}"

echo -e "${LOG_COLOR}Backup completed successfully.${RESET}"

3. Identifying Maximum Disk Utilization

This utility scans all mounted file systems to determine the partition with the highest storage usage percentage and returns the value.

#!/bin/bash
# Filename: max_disk_usage.sh

# Filter df output for percentage, remove symbols, sort numerically, and take the top value
MAX_USAGE=$(df -h | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{print $5}' | tr -d '%' | sort -rn | head -n 1)

echo "The highest disk utilization rate is currently: ${MAX_USAGE}%"

4. Monitoring Remote Connections

This script analyzes established remote connections by counting the number of sessions per unique IP address and sorting them by frequency.

#!/bin/bash
# Filename: connection_audit.sh

# Extract login info, isolate IPs, count occurrences, and sort
echo "Active Remote Connections:"
w -h | awk '{print $3}' | sort | uniq -c | sort -rn

5. Argument Handlnig and File Analysis

This script validates command-line arguments. If a valid file is provided, it counts the number of empty lines contained within.

#!/bin/bash
# Filename: analyze_file.sh

# Check argument count
if [ $# -eq 0 ]; then
    echo "Error: Please provide a file path as an argument."
    exit 1
fi

TARGET_FILE="$1"

# Check if the path exists and is a regular file
if [ -f "$TARGET_FILE" ]; then
    # Count empty lines using grep
    BLANK_COUNT=$(grep -c "^$" "$TARGET_FILE")
    echo "File '$TARGET_FILE' contains $BLANK_COUNT empty lines."
else
    echo "Error: The specified path is not a valid file."
fi

6. Network Connectivity Check

This tool accepts an IP address as input and verifies network reachability using ICMP ping requests.

#!/bin/bash
# Filename: net_check.sh

if [ $# -ne 1 ]; then
    echo "Usage: $0 [IP_ADDRESS]"
    exit 1
fi

TARGET_IP="$1"

# Send 1 packet, wait 1 second, suppress output
ping -c 1 -W 1 "$TARGET_IP" > /dev/null 2>&1

if [ $? -eq 0 ]; then
    echo "Success: Host at $TARGET_IP is reachable."
else
    echo "Failure: Host at $TARGET_IP is unreachable."
fi

7. Storage and Inode Capacity Alert

A monitoring script that checks both disk space usage and inode utilization. If either metric exceeds the 80% threshold, it broadcasts a warning to all logged-in users.

#!/bin/bash
# Filename: capacity_monitor.sh

THRESHOLD=80

# Check Disk Usage
DISK_VAL=$(df | grep -vE '^Filesystem|tmpfs' | awk '{print $5}' | tr -d '%' | sort -rn | head -n 1)
if [ "$DISK_VAL" -ge "$THRESHOLD" ]; then
    wall "Warning: Disk space usage has exceeded ${THRESHOLD}%!"
fi

# Check Inode Usage
INODE_VAL=$(df -i | grep -vE '^Filesystem|tmpfs' | awk '{print $5}' | tr -d '%' | sort -rn | head -n 1)
if [ "$INODE_VAL" -ge "$THRESHOLD" ]; then
    wall "Warning: Inode usage has exceeded ${THRESHOLD}%!"
fi

8. Verifying File Read/Write Permissions

This script determines if the current user lacks both read and write permissions for a specified file.

#!/bin/bash
# Filename: check_perms.sh

FILE_PATH="$1"

if [ -z "$FILE_PATH" ]; then
    echo "Please provide a file path."
    exit 1
fi

if [ -f "$FILE_PATH" ]; then
    # Check if file is NOT readable AND NOT writable
    if [ ! -r "$FILE_PATH" ] && [ ! -w "$FILE_PATH" ]; then
        echo "Access Denied: You have neither read nor write permissions for '$FILE_PATH'."
    else
        echo "Access Granted: You have read or write permissions for '$FILE_PATH'."
    fi
else
    echo "Error: '$FILE_PATH' is not a valid file."
fi

9. Automating Script Permissions

This snippet prompts the user for a filename. If the file is a shell script (ending in .sh), it automatically grants execute permissions.

#!/bin/bash
# Filename: auto_exec.sh

read -p "Enter the script filename: " USER_FILE

if [ -f "$USER_FILE" ]; then
    if [[ "$USER_FILE" == *.sh ]]; then
        chmod +x "$USER_FILE"
        echo "Execute permissions added to $USER_FILE"
    else
        echo "Notice: The file is not a .sh script."
    fi
else
    echo "Error: File not found."
fi

10. Managing System Logins

These scripts demonstrate how to toggle the ability for regular users to log into the system by creating or removing the /etc/nologin file.

Disable User Logins:

#!/bin/bash
if [ -f /etc/nologin ]; then
    echo "Standard user logins are already disabled."
else
    touch /etc/nologin
    echo "Standard user logins have been disabled."
fi

Enable User Logins:

#!/bin/bash
if [ -f /etc/nologin ]; then
    rm -f /etc/nologin
    echo "Standard user logins have been enabled."
else
    echo "Standard user logins are already enabled."
fi