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sparse_file_manipulation

🕳️ Create and Manage Sparse Files via FFI or truncate​

Sparse files let you allocate large logical sizes without consuming physical disk blocks. Use File#truncate or lseek with SEEK_DATA/SEEK_HOLE (Linux/Mac) for advanced sparse manipulation.

file = File.open('sparse.bin', 'wb+')
# Create a 10GB sparse file
file.truncate(10 * 1024**3)

# Write a small header
file.seek(0)
file.write("HEADER")

# Seek to offset and write footer
file.seek(9 * 1024**3)
file.write("FOOTER")
file.close

# Inspect holes and data extents (via FFI)
# Use `lseek(fd, offset, SEEK_DATA)` and `SEEK_HOLE` to discover blocks

Sparse files are ideal for VM disk images or huge file placeholders without paying the full storage cost.