ncdu

Additional Notes

ncdu (NCurses Disk Usage) is an interactive disk usage analyzer that shows a navigable, text-based interface of disk usage. It scans a directory tree and displays directories and files sorted by size, allowing you to quickly identify what is consuming the most space.

It is more convenient than repeatedly running du -sh because you can browse interactively, delete files from within the interface, and see a real-time breakdown of space usage. It is invaluable for cleaning up old log files, caches, virtual machines, and large media files.

Syntax

ncdu [options] [directory]

Parameters

• directory: The directory to scan. Defaults to the current directory.

Common Options

• -o file: Export the scan results to a file for later analysis.
• -f file: Load a previously exported scan file instead of scanning.
• -x: Stay on the same filesystem (do not cross mount points).
• -e: Enable extended information (file modification time, permissions, etc.).
• -q: Quiet mode; reduce refresh rate for faster scanning on slow terminals.
• -r: Read-only mode; disable delete and shell spawning.
• -s: Show only directories (skip individual files).
• --exclude pattern: Exclude files matching a pattern.
• --exclude-caches: Exclude cache directories.
• --color scheme: Choose color scheme (off, dark, dark-bg).
• --si: Use SI units (1000) instead of binary (1024).

Interactive Keys

• Arrow keys or j/k: Navigate the file list.
• Enter: Enter a directory.
• g: Jump to the top of the list.
• n: Sort by name.
• s: Sort by size.
• d: Delete the selected file or directory.
• r: Refresh/rescan the current directory.
• i: Show information about the selected item.
• t: Toggle between showing directories and files.
• q: Quit ncdu.

Examples

ncdu

Scan the current directory and show disk usage interactively.

ncdu /var/log

Scan /var/log to see which log files are using the most space.

ncdu -x /

Scan the root filesystem but do not cross filesystem boundaries.

ncdu -o scan.txt /home
ncdu -f scan.txt

Export a scan to a file, then view it later without re-scanning.

ncdu --exclude "*.bak" --exclude ".cache" /home/user

Scan the home directory excluding backup and cache files.

Practical Notes

• Press d to delete a file or directory from within ncdu. This is irreversible.
• Use -x when scanning / to avoid scanning mounted filesystems like /proc, /sys, or network mounts.
• Exporting a scan (-o) is useful for sharing disk usage data without sharing file contents.
• ncdu refreshes its display after each keypress, making it fast even on large directory trees.