View source for File header

A '''file header''' is a portion of [[INDEXF.SYS]] that contains file information such as [[File ID|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.

<pre>$ dump/header/block=count=0 a.txt;1</pre>

=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.
* [[F$FILE_ATTRIBUTES()]]\\
This lexical function lets you access the attributes for a specific file.