Linux Checking Disk Usage - Complete Disk Monitoring Guide

Real-World Disk Usage Examples

# 1. Complete Disk Usage Report Script
#!/bin/bash
echo "=== Disk Usage Report $(date) ==="
echo -e "\n1. Filesystem Usage:"
df -h
echo -e "\n2. Inode Usage:"
df -i
echo -e "\n3. Large Directories in /:"
du -h --max-depth=1 / 2>/dev/null | sort -hr | head -10
echo -e "\n4. Large Files (>100MB):"
find / -type f -size +100M 2>/dev/null | xargs ls -lh | head -10
echo -e "\n5. Log Directory Analysis:"
du -h --max-depth=1 /var/log 2>/dev/null | sort -hr

# 2. Automated Cleanup Script
#!/bin/bash
THRESHOLD=90
CURRENT_USAGE=$(df / --output=pcent | tail -1 | tr -d '% ')

if [ $CURRENT_USAGE -gt $THRESHOLD ]; then
    echo "Disk usage is ${CURRENT_USAGE}%. Starting cleanup..."
    
    # Clean package cache
    sudo apt-get autoremove -y
    sudo apt-get autoclean -y
    
    # Clean temporary files
    sudo find /tmp -type f -atime +7 -delete
    sudo find /var/tmp -type f -atime +7 -delete
    
    # Clean old logs
    sudo find /var/log -name "*.log" -type f -mtime +30 -delete
    sudo journalctl --vacuum-time=7d
    
    # Clean thumbnail cache
    rm -rf ~/.cache/thumbnails/*
    
    echo "Cleanup completed."
else
    echo "Disk usage (${CURRENT_USAGE}%) is below threshold (${THRESHOLD}%)."
fi

# 3. Directory Size Monitor
#!/bin/bash
WATCH_DIR="/var/log"
MAX_SIZE="10G"

while true; do
    CURRENT_SIZE=$(du -s $WATCH_DIR | cut -f1)
    if [ $CURRENT_SIZE -gt ${MAX_SIZE%G}000000 ]; then
        echo "WARNING: $WATCH_DIR size ($(du -sh $WATCH_DIR | cut -f1)) exceeds $MAX_SIZE"
        # Add alert actions here
    fi
    sleep 300
done

# 4. Find and Archive Old Logs
#!/bin/bash
LOG_DIR="/var/log"
ARCHIVE_DIR="/archive/logs"
RETENTION_DAYS=30

echo "Archiving logs older than $RETENTION_DAYS days..."
find $LOG_DIR -name "*.log" -type f -mtime +$RETENTION_DAYS | while read file; do
    archive_file="$ARCHIVE_DIR/$(basename $file).$(date +%Y%m%d).gz"
    echo "Archiving $file to $archive_file"
    sudo gzip -c "$file" > "$archive_file"
    sudo truncate -s 0 "$file"
done

# 5. Disk Usage Alert System
#!/bin/bash
THRESHOLD=85
ALERT_EMAIL="admin@example.com"

df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output; do
    usage=$(echo $output | awk '{ print $1}' | cut -d'%' -f1)
    partition=$(echo $output | awk '{ print $2 }')
    
    if [ $usage -ge $THRESHOLD ]; then
        echo "Alert: Partition $partition is ${usage}% full" | \
        mail -s "Disk Space Alert: $partition ${usage}%" $ALERT_EMAIL
    fi
done

# 6. Interactive Disk Analyzer
#!/bin/bash
echo "Interactive Disk Analyzer"
PS3="Select an option: "
options=("Quick Overview" "Large Files Search" "Directory Analysis" "Cleanup Suggestions" "Quit")

select opt in "${options[@]}"; do
    case $opt in
        "Quick Overview")
            echo "=== Quick Overview ==="
            df -h
            echo -e "\nTop 5 largest directories in /home:"
            du -h --max-depth=1 /home 2>/dev/null | sort -hr | head -6
            ;;
        "Large Files Search")
            read -p "Enter minimum size (e.g., 100M): " size
            echo "Finding files larger than $size..."
            find / -type f -size "+$size" 2>/dev/null | xargs ls -lh | head -20
            ;;
        "Directory Analysis")
            read -p "Enter directory to analyze: " dir
            if [ -d "$dir" ]; then
                ncdu "$dir"
            else
                echo "Directory not found: $dir"
            fi
            ;;
        "Cleanup Suggestions")
            echo "=== Cleanup Suggestions ==="
            echo "1. Package cache: $(du -sh /var/cache/apt 2>/dev/null || echo 'N/A')"
            echo "2. Log files: $(du -sh /var/log 2>/dev/null || echo 'N/A')"
            echo "3. Temporary files: $(du -sh /tmp 2>/dev/null || echo 'N/A')"
            echo "4. User caches: $(du -sh ~/.cache 2>/dev/null || echo 'N/A')"
            ;;
        "Quit")
            break
            ;;
        *) echo "Invalid option";;
    esac
done

# 7. Duplicate File Finder
#!/bin/bash
SEARCH_DIR="/home"
RESULTS_FILE="/tmp/duplicates.txt"

echo "Searching for duplicate files in $SEARCH_DIR..."
fdupes -r "$SEARCH_DIR" > "$RESULTS_FILE"

if [ -s "$RESULTS_FILE" ]; then
    echo "Found duplicates. Review $RESULTS_FILE"
    echo "Total duplicates found: $(grep -c "^$" "$RESULTS_FILE")"
else
    echo "No duplicates found."
    rm -f "$RESULTS_FILE"
fi

# 8. Growth Trend Analysis
#!/bin/bash
LOG_FILE="/var/log/disk_usage.log"
echo "$(date),$(df / --output=used | tail -1),$(df / --output=avail | tail -1)" >> "$LOG_FILE"

# Generate weekly report
if [ $(date +%u) -eq 1 ]; then  # Monday
    echo "=== Weekly Disk Usage Report ==="
    echo "Date,Used,Available"
    tail -7 "$LOG_FILE"
fi

# 9. Docker Disk Cleanup
#!/bin/bash
echo "Cleaning up Docker disk usage..."
docker system df
echo -e "\nRemoving unused containers, networks, and images..."
docker system prune -f
echo -e "\nRemoving build cache..."
docker builder prune -f
echo -e "\nCurrent Docker disk usage:"
docker system df

# 10. MySQL/PostgreSQL Table Size Analysis
#!/bin/bash
# MySQL version
mysql -e "
SELECT table_schema as 'Database',
ROUND(SUM(data_length + index_length) / 1024 / 1024, 2) as 'Size (MB)'
FROM information_schema.TABLES 
GROUP BY table_schema
ORDER BY SUM(data_length + index_length) DESC;"

# PostgreSQL version
psql -c "
SELECT datname, pg_size_pretty(pg_database_size(datname)) 
FROM pg_database 
ORDER BY pg_database_size(datname) DESC;"

# 11. Web Server Log Analysis
#!/bin/bash
LOG_DIR="/var/log/nginx"
echo "Web Server Log Analysis:"
echo "Total log size: $(du -sh $LOG_DIR)"
echo "Number of log files: $(find $LOG_DIR -name "*.log" | wc -l)"
echo "Largest log files:"
find $LOG_DIR -name "*.log" -exec du -h {} \; | sort -hr | head -5

# 12. User Home Directory Quotas
#!/bin/bash
echo "User Home Directory Sizes:"
for user in /home/*; do
    if [ -d "$user" ]; then
        size=$(du -sh "$user" 2>/dev/null | cut -f1)
        echo "$(basename $user): $size"
    fi
done | sort -k2 -hr

# 13. Backup Size Monitor
#!/bin/bash
BACKUP_DIR="/backup"
MAX_BACKUP_SIZE="100G"
CURRENT_SIZE=$(du -s $BACKUP_DIR | cut -f1)
MAX_SIZE_BYTES=$(echo $MAX_BACKUP_SIZE | sed 's/G/*1024*1024*1024/' | bc)

if [ $CURRENT_SIZE -gt $MAX_SIZE_BYTES ]; then
    echo "Backup size ($(du -sh $BACKUP_DIR | cut -f1)) exceeds limit ($MAX_BACKUP_SIZE)"
    echo "Rotating backups..."
    # Add backup rotation logic here
fi

# 14. Container Storage Analysis
#!/bin/bash
echo "Container Storage Analysis:"
echo "Docker:"
docker system df
echo -e "\nPodman:"
podman system df
echo -e "\nLXC:"
lxc storage list
echo -e "\nKubernetes PVCs:"
kubectl get pvc --all-namespaces

# 15. Automated Report Generator
#!/bin/bash
REPORT_FILE="/var/log/disk-report-$(date +%Y%m%d).txt"
{
    echo "Disk Usage Report - $(date)"
    echo "========================"
    echo -e "\nFilesystem Overview:"
    df -h
    echo -e "\nInode Usage:"
    df -i
    echo -e "\nLarge Directories:"
    du -h --max-depth=1 / 2>/dev/null | sort -hr | head -10
    echo -e "\nLarge Files:"
    find / -type f -size +500M 2>/dev/null | xargs ls -lh 2>/dev/null | head -10
} > $REPORT_FILE

echo "Report generated: $REPORT_FILE"