ftruncate64 - Linux


ftruncate64 modifies the size of a file to the specified length in bytes. It effectively truncates or extends the file as needed. This command is commonly used for file manipulation, resizing partitions, or allocating disk space.


ftruncate64 [-h] [-c] [-e FALLBACK] FILENAME LENGTH


  • -h, –help: Display usage information.
  • -c: Do not follow symbolic links.
  • -e FALLBACK: Specifies the fallback size to be used when the requested length is not valid. The default fallback size is 0.


Truncate a file to 100 bytes

ftruncate64 file.txt 100

Extend a file to 2GB

ftruncate64 file.img 2048m

Common Issues

  • Incorrect Length: Ensure the specified length is valid for the file system and file type.
  • Permissions: Verify that you have the necessary permissions to modify the file.


ftruncate64 can be used in conjunction with other commands, such as:

  • truncate: A version of ftruncate64 that works on 32-bit systems.

Related Commands

  • truncate: Modify the size of a file to a specific length.
  • dd: Copy and convert data.
  • resize2fs: Resize an ext2/ext3/ext4 file system.