cfdisk Command Examples

🎯 cfdisk vs fdisk vs parted

⚙️ Common cfdisk Workflows

Setting Up a New Data Disk:

1. Identify disk: lsblk or sudo fdisk -l
2. Launch cfdisk: sudo cfdisk -z -t gpt /dev/sdX
3. Select GPT label type (for modern systems)
4. Create new partition: Navigate to free space, select [New]
5. Accept default size (entire disk) or specify custom size
6. Change type if needed (select [Type] for swap, LVM, etc.)
7. Write changes: Select [Write], type "yes"
8. Format partition: sudo mkfs.ext4 /dev/sdX1
9. Mount and use: sudo mount /dev/sdX1 /mnt/data
10. Add to fstab for persistent mounting

Reclaiming Space by Removing Partition:

1. Backup any important data from partition
2. Unmount partition: sudo umount /dev/sdX2
3. Remove fstab entry (edit /etc/fstab)
4. Launch cfdisk: sudo cfdisk /dev/sdX
5. Navigate to partition to delete
6. Select [Delete], confirm with "yes"
7. Space now shows as "Free space"
8. Can create new partition or resize adjacent partition
9. Write changes: Select [Write], type "yes"

Creating Multiple Partitions:

1. Launch cfdisk on target disk
2. For first partition: Select free space → [New] → Enter size (e.g., 100G)
3. Set type if needed: [Type] → Select appropriate type
4. For second partition: Navigate to remaining free space → [New] → Enter size
5. Repeat for additional partitions
6. Review entire layout carefully
7. Write changes when satisfied
8. Format each partition with desired filesystem

🔒 Safety Features in cfdisk

• Visual Confirmation: Always shows exactly which partition/space is selected
• In-Memory Changes: All modifications stay in RAM until explicit Write
• "yes" Requirement: Must type "yes" (exactly) to confirm writes and deletes
• Uppercase W: Write command requires uppercase to prevent accidental activation
• Quit Safety: Warns if quitting with unsaved changes
• Clear Indicators: Color coding and highlighting show current selection
• Help Always Available: Press 'h' anytime for command reference
• No Destructive Defaults: Never automatically writes without explicit command

💡 Best Practices

• Backup First: Always backup important data before partitioning operations
• Verify Device: Double-check you're working on correct disk with lsblk
• Unmount Before Changes: Unmount partitions before deleting or resizing
• Use GPT for New Disks: Modern standard, better for disks > 2TB
• Alignment Automatic: cfdisk handles sector alignment automatically
• Review Before Writing: Carefully examine full partition table before committing
• Document Layout: Save partition information: sudo sfdisk -d /dev/sda > backup.txt
• Test in VM First: Practice complex operations in virtual machine
• Keep Boot Media Ready: Have rescue USB available for recovery
• Check After Writing: Verify changes with lsblk -f

🐛 Troubleshooting Common Issues

Problem: "Device or resource busy"

Solution: Partition is mounted or in use. Check with mount | grep sdX and lsof /dev/sdX1, then unmount before proceeding.

Problem: Changes not visible after writing

Solution: Kernel may not have updated partition table. Run sudo partprobe /dev/sdX or reboot system to refresh.

Problem: cfdisk exits with "Cannot open /dev/sdX"

Solution: Need root privileges. Use sudo cfdisk /dev/sdX or run as root. Also verify device exists with ls /dev/sd*.

Problem: Terminal too small for cfdisk display

Solution: cfdisk requires minimum 80x24 character terminal. Resize terminal window or use stty size to check current size.

Problem: Partition numbering gaps after deletion

Solution: Normal behavior - partition numbers don't automatically renumber. If this bothers you, use 's' command to sort, but it's purely cosmetic and unnecessary.

🔧 Command-Line Options

📚 Related Commands

• fdisk: Command-line partition editor (more scripting-friendly)
• gdisk: GPT-focused partition editor with advanced features
• parted: Powerful partition editor that can resize filesystems
• sfdisk: Scriptable partition table manipulator
• partprobe: Inform kernel of partition table changes
• lsblk: List block devices and partitions in tree format
• blkid: Display partition UUIDs and filesystem types
• mkfs: Create filesystems on partitions

🎓 When to Use cfdisk

cfdisk is IDEAL for:

• Interactive partition management on single disks
• Users who prefer visual feedback over command-line
• Learning partition management (safest for beginners)
• Quick partition table review and minor adjustments
• Systems where you need to work directly on console
• Situations where you want clear visual confirmation before writing

Use fdisk instead when:

• Scripting partition operations
• Working over slow SSH connections (less terminal overhead)
• Need to quickly check partition tables (fdisk -l)
• Advanced features like partition UUID changes

Use parted instead when:

• Need to resize both partition table AND filesystem together
• Complex operations requiring precise sector control
• Scripting with more advanced features
• Working with exotic partition table types