File header
A file header is a portion of INDEXF.SYS that contains file information such as file ID, file name, modification date, owner, protection code, pointers to data on disk, etc.
File headers consist of three major parts:
- An area that contains File ID, organization, owner, protection code and pointers to the map and ACL areas
- An identification area containing name and date information
- The map/ACL area containing ACL and pointers (offsets) to data on disk
Viewing a file header
To view a file header, you can use the DUMP/HEADER command. To avoid seeing the ACL list that is also being dumped, specify /BLOCK=COUNT=0.
$ dump/header/block=count=0 a.txt;1
Fragmentation
Sometimes a file can have a large ACL or be very fragmented on the disk; in this case, multiple file headers can be allocated to that file so that the original file header contains the location of the extension file header, and so on.
Alternative ways to view file information
There are ways to view file attributes and information contained in the file header:
- DIRECTORY /FULL\\
This command displays the size, owner, important dates associated with the file, and some attributes.
This lexical function lets you access the attributes for a specific file.
