


1 MBOX
   Displays information on mailboxes (MBAnnnn:   devices)  within  the
   system.

   Format

     MBOX mailboxname

2 PARAMETER
  mailboxname
     Specifies the name of  the  mailbox  to  be  examined.   Wildcard
     characters  (*  and  %)  are  allowed.   Mailboxs are selected by
     matching the following:

     1.  Physical device name MBAnnnn

     2.  Logical name created by the the $CREMBX system service


                                   NOTE

             Logical  names  are  matched  regardless  of  the
             logical  name table that contains them.  This can
             cause multiple mailboxes to be returned on  exact
             name  matches  even  though only one logical name
             might be seen with a 'show logical' command.

2 /BYTE
 Formats the mail messages in bytes.  The /BYTE, /LONGWORD, and  /WORD
 qualifiers are mutually exclusive.
2 /DECIMAL
 Dumps mail messages in decimal  radix.   The  /DECIMAL,  /HEXADECIMAL
 (default), and /OCTAL qualifiers are mutually exclusive.

                                 NOTE

         Decimal numbers are displayed as unsigned quantities.

2 /GROUP
    /GROUP[=groupid]

 Causes MBOX to only display mailboxs  own  by  processes  within  the
 specified  group.   Groupid  may  be  a  group identifier or an octal
 number.  Ommission of groupid causes MBOX to use the  current  group.
 This qualifier is useful if you have a number of equivalent mailboxes
 across different groups.
2 /HEADERS
    /HEADERS (default)
    /NOHEADERS

 Includes header information for all mailboxes matching the  specified
 mailbox  name.   By  default  headers  are  only printed for mailboxs
 matching other criterion such as /PENDING_READS or /MESSAGE.
2 /HEXADECIMAL
    /HEXADECIMAL (default)

 Dumps mail messages in hexadecimal radix.  The /DECIMAL, /HEXADECIMAL
 (default), and /OCTAL qualifiers are mutually exclusive.
2 /LONGWORD
    /LONGWORD (default)

 Formats the mail messages in longwords.  The  /BYTE,  /LONGWORD,  and
 /WORD qualifiers are mutually exclusive.
2 /MESSAGES
    /MESSAGES (default)
    /NOMESSAGES

 Selects mailboxs that contain messages.
2 /OCTAL
 Dumps mail messages  in  octal  radix.   The  /DECIMAL,  /HEXADECIMAL
 (default), and /OCTAL qualifiers are mutually exclusive.
2 /OUTPUT
    /OUTPUT=filename

 Specifies the output file for the dump.  If the /OUTPUT qualifier  is
 not  specified,  the dump goes to SYS$OUTPUT.  No wildcard characters
 are allowed.
2 /PENDING_READS
    /PENDING_READS (default)
    /NOPENDING_READS

 Selects mailboxs that have asynchronous reads pending on them.
2 /READ_ATTENTION
    /READ_ATTENTION (default)
    /NOREAD_ATTENTION

 Selects mailboxs that have read attention ASTs on them.
2 /RWMBX
    /RWMBX (default)
    /NORWMBX

 Selects mailboxs that have processes waiting in RWMBX for free  space
 within them.
2 /WORD
 Formats the mail messages in words.  The /BYTE, /LONGWORD, and  /WORD
 qualifiers are mutually exclusive.
2 /WRITE_ATTENTION
    /WRITE_ATTENTION (default)
    /NOWRITE_ATTENTION

 Selects mailboxs that have write attention ASTs on them.
2 Format_of_output
3 Header_format
The format of the header lines is:

Device: MBA4 (CLU$CONFIGURE_MBX), Channels: 7, Operations: 211

   Total size: 1056, Remaining: 1056, Message size: 256, Msgs: 0

"Device" gives  the  physical  device  name  "MBA4:"  of  the  mailbox
followed  by  the  logical name that was defined when this mailbox was
created "CLU$CONFIGURE_MBX".

"Channels" gives the total number of channels assigned to the  mailbox
either  by  calls  to  SYS$ASSIGN  or SYS$CREMBX.  This count does not
include the channel that MBOX assigns to the device.

"Operations" gives the total number  of  SYS$QIO  requests  that  have
completed for this device.

"Total size" gives the total size of the mailbox in bytes.

"Remaining"  gives  the  space  remaining  in  bytes  for   additional
messages.

"Message size" gives the maximum size of  a  single  mailbox  message.
This may exceed the size of the size of the mailbox in which case mail
messages are limited to the size of the mailbox.

"Msgs" gives the total number of mail  messages  within  the  mailbox.
Due  to  the dynamic nature of the system the number of messages given
by this field and the number of messages printed out may differ.
3 RWMBX_format
MBA6533 (ERRORLOGMBX), Channels: 4, Operations: 729168

   Total size: 3600, Remaining: 35, Message size: 956, Msgs: 18

   RWMBX, PID: 4240261A (DEVC_TRANSERV)

   RWMBX, PID: 424049F1 (DEVC_MARKER)

This display  shows  two  processes  (DEVC_TRANSERV  and  DEVC_MARKER)
waiting  for  space  within  a  mailbox  (ERRORLOGMBX).  Both of these
processes must be trying to write a message that contains more than 35
bytes (remaining space within the mailbox).
3 Read_attention_format
READATTN, PID: 41600106 (CONFIGURE), Mode: U, ADR: 0000F7B2, PRM: 0000E175

"PID" gives the process identification of the process  with  the  read
attention AST queued followed by the name of the process.

"Mode" gives the current access mode of the attention AST.  Can be one
of User, Supervisor, Executive or Kernel.

"ADR" gives the address of the routine that  will  be  called  at  AST
level on a read to the mailbox.

"PRM" gives the AST parameter associated with this I/O request.
3 Write_attention_format
WRTATTN, PID: 41600106 (CONFIGURE), Mode: U, ADR: 0000F7B2, PRM: 0000E175

"PID" gives the process identification of the process with  the  write
attention AST queued followed by the name of the process.

"Mode" gives the current access mode of the attention AST.  Can be one
of User, Supervisor, Executive or Kernel.

"ADR" gives the address of the routine that  will  be  called  at  AST
level on a write to the mailbox.

"PRM" gives the AST parameter associated with this I/O request.
3 Pending_read_format
READIO, PID: 41600107 (IPCACP), Mode: K, ADR: 00000000, PRM: 00000000

"PID" gives the process identification of the process with the pending
read followed by the name of the process.

"Mode" gives the current access mode of the read.  Can be one of User,
Supervisor, Executive or Kernel.

"ADR" gives the address of the routine that  will  be  called  at  AST
level on I/O completion.

"PRM" gives the AST parameter associated with this I/O request.
3 Message_format
Default message format /HEXADECIMAL/LONGWORD:

Message number: 1, 13 bytes, Written by: 41600698 (_LTA5069:)

               33 20322031 20676E69 74736554 Testing 1 2 3....... 00000000

Message format /DECIMAL/WORD

Message number: 1, 13 bytes, Written by: 41600698 (_LTA5069:) Waiting

         51  8242  8241  8295 28265 29811 25940 Testing 1 2 3...        0

                                 NOTE

        The "Waiting" within the message header  is  displayed
        when  the  process  did not issue an IO$M_NOW modifier
        with the IO$_WRITEVBLK function code.

