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© January 1997 Tony Lawrence

On older SCO, you could print the contents of a directory file in hexadecimal format by the command "hd ." (current directory).

With SCO OpenServer you get only 0000.

That's not good :-)

Typically, the reason for doing this was to either to see the order of the files in the directory (so you could tell how far along a backup or restore was that you were watching on another screen) or to look for "holes" (so that you could rearrange the order of entries by judicious copying and deleting). Why would you want to do that? If you have to ask, you'll probably never want to, but in some situations involving large directories and ultra critical performance, it's worth moving frequently accessed files to the "top", (assuming the namei cache can't help you, perhaps because you need that boost on the *first* access).

Yet another reason was to spot garbage characters in file names.

If all you need is the order of file names in the slots, ls -f will do it. Otherwise, you can get some of the remaining functionality by a simple C program like this:

#include <dirent.h>
#include <stdio.h>
DIR *dirp;
char *c;
long offset=0L;
struct dirent *dp;
dirp = opendir( "." );
while ( (dp = readdir( dirp )) != NULL )
        printf("Inode: %8lu Offset %4ld Length %4hd ", dp->d_ino,offset,dp->d_reclen);
        printf("%s ",dp->d_name);
        offset = dp->d_off;
        while (*c)
        printf("%x ",*c++);

closedir( dirp );

You can add to this to display other information, of course, but while it does show the order, it doesn't show holes. You can infer holes from the directory size and offsets, and you can create holes where you want them by removing or copying files, but it's certainly true that an hd on a directory was useful now and then.

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