[Info-vax] Search for folders

[Arne Vajhøj]

On 1/27/2024 3:06 PM, Arne Vajhøj wrote:
> On 1/27/2024 1:48 PM, Single Stage to Orbit wrote:
>> In my system account when I log in and run the dir command it shows me
>> this:
>>
>> $ dir/page
>>
>> Directory SYS$SYSROOT:[SYSMGR]
> 
>> Total of 25 files.
>>
>> Directory SYS$COMMON:[SYSMGR]
> 
>> [ snip ]
>>
>> Why does it shows me two directories?
> 
> Now it starts to become a little bit tricky to explain.
> 
> Let us start with the practical version.
> 
> In VMS "default directory" does not need to be
> a single directory - it can actually be a list of
> directories.
> 
> When opening an existing file all in the list are searched.
> 
> When creating a new file it get created in the first
> in the list.
> 
> It is rarely used by VMS users.
> 
> But it is used by VMS itself.
> 
> SYS$SYSROOT:[SYSMGR] is really disk:[SYSn.SYSMGR]
> SYS$COMMON:[SYSMGR] is really disk:[VMS$COMMON.SYSMGR] *and* 
> disk:[SYSn.SYSCOMMON.SYSMGR]
> 
> It is a cluster thing.
> 
> disk:[SYS0.SYSMGR] contains file specific for node 0
> disk:[SYS1.SYSMGR] contains file specific for node 1
> disk:[SYS2.SYSMGR] contains file specific for node 2
> 
> disk:[VMS$COMMON.SYSMGR] = disk:[SYS0.SYSCOMMON.SYSMGR] = 
> disk:[SYS1.SYSCOMMON.SYSMGR] = disk:[SYS2.SYSCOMMON.SYSMGR] contains 
> files shared by all 3 nodes
> 
> So as a system manager you can have COM files specific for a node
> or shared for all nodes.
> 
> Powerful.
> 
> But also potential confusing.

And regarding the technical stuff behind it, then
it is possible because:
* the device part and the directory part of default
   are store separately (in a logical SYS$DISK and
   in process memory respectively)
* the device part does not need to be a device only
   but can be a device plus a directory accessed via
   a so called rooted logical
* a logical can have multiple values

Here comes a user example.

$ dir [...]

Directory DKA0:[arne.fun]

fun.txt;1           morefun.DIR;1

Total of 2 files.

Directory DKA0:[arne.fun.morefun]

morefun.txt;1

Total of 1 file.

Grand total of 2 directories, 3 files.

$ define/nolog funroot DKA0:[arne.fun.] /transl=(conc,term)
$ define/nolog morefunroot DKA0:[arne.fun.morefun.] /transl=(conc,term)
$ dir funroot:[000000]

Directory FUNROOT:[000000]

fun.txt;1           morefun.DIR;1

Total of 2 files.
$ dir morefunroot:[000000]

Directory MOREFUNROOT:[000000]

morefun.txt;1

Total of 1 file.

$ define/nolog doublefunroot funroot,morefunroot
$ dir doublefunroot:[000000]

Directory funroot:[000000]

fun.txt;1           morefun.DIR;1

Total of 2 files.

Directory morefunroot:[000000]

morefun.txt;1

Total of 1 file.

Grand total of 2 directories, 3 files.

Arne