fstat64 - Linux


fstat64 retrieves information about the open file descriptor provided. This command is commonly used to obtain metadata about files, directories, and other file system objects.


fstat64 <file descriptor>




Retrieve file metadata:

fstat64 3

Obtain file size:

fstat64 /proc/self/fd/1 | awk '{print $7}'

Check file type (regular file, directory, etc.):

fstat64 3 | grep "File type:"

Common Issues

  • Invalid file descriptor: Ensure the provided file descriptor is valid and refers to an open file.
  • Permission errors: The user may not have sufficient permissions to access the file.
  • Stale file descriptor: If the file has been closed or moved since the file descriptor was obtained, the command may return an error.


Combine with other commands:

  • lsof: Identify the process associated with a file descriptor.
  • du: Calculate disk usage based on file size information obtained from fstat64.

Related Commands

  • stat: Similar to fstat64, but operates on file paths.
  • ls: List file metadata, including file descriptor numbers.