The following sections describe how to use snapshot on both
    Tru64 UNIX and OpenVMS.

1  –  Tru64 UNIX

    Snapshot saves all of the counter attributes available
    from the specified entity at that time. You can snapshot only
    counters, and the results are displayed using a subsequent
    show command. For example, do either of the following:

    ncl> snapshot node 0 all counters

    or

    ncl> snapshot node 0 all counters, to file_name

    If you omit the attribute list entirely from the snapshot
    command, NCL defaults to all counters.

    If you do not choose a file name, NCL retains the binary data
    in memory. If you enter the show command for which the remote
    entity returns any counters, NCL tries to find snapshot data
    in the snapshot file you specified (or within its memory, if
    you did not specify a file name).

    If your show command does not contain the from preposition, NCL
    tries to find a corresponding snapshot in memory. If you
    have not performed a snapshot command in this NCL session, NCL
    displays just the raw counters.

    If the show command does contain the from preposition, NCL tries
    to read the specified file. If NCL cannot open the file, it
    returns the appropriate error message and displays the data
    returned from the entity. If a snapshot file exists, but does
    not contain data from the current entity, NCL displays just the
    raw counters.

    If NCL succeeds in finding a saved snapshot of the entity's
    counters, then it displays the counters returned by the agent.
    The following example shows a typical snapshot file, in this
    instance called x.tmp:

    ncl> snapshot 12.80 csm sta * oct se, oct r, to x.tmp

    To recall the snapshot file x.tmp, you would use the following
    command:

    show n 12.80 csm sta *, from x.tmp

    Node 12.80 CSMA-CD Station csmacd-1
    AT 1994-09-08-11:12:01.497-04:00I0.165
    Snapshot Elapsed Time = +0-02:01:47.536I0.428

                       Current     Snapshot    Difference
                       -------     --------    -----------
   Counters
    Octets Sent        64354851    45070297    19284554
    Octets Received    34030180    27575906    6454274

    To list all the snapshots that NCL is holding "in memory,"
    use the command:

    ncl> show ncl snapshots

    To eliminate the snapshot corresponding to a value, thus
    allowing counters to be displayed in the normal name=value
    format, use the command:

    ncl> clear ncl snapshot 50

    without this, the only way to get back to a normal display
    is to exit NCL and reinvoke it.

    To periodically poll the value of a counter and display it
    (using the snapshot format) until ^C'ed, use the command:

    ncl> cmonitor entity counter

    this is similar to netstat and iostat which allow you to
    monitor a value by specifying an interval.

    To control what the interval between polls should be, use
    the commands:

    ncl> set ncl cmonitor time = 5
    ncl> show ncl cmonitor time

2  –  OpenVMS

    The snapshot function saves the counters' values and displays
    those values. After the snapshot command is issued, the show
    command can be used to display a comparison of the current
    values and the registered values at later times.

    The following command activates snapshot for the entity and
    produces the snapshot output:

    NCL> snap nsp port nsp$port_0000200f all counters

    Snapshot node 0 NSP Port NSP$PORT_0000200F
    at 1994-09-18-19:49:11.76078 - 04:00 I 52.08425

    Counters
      Creation Time = 1991-09-18-18:55:25.59899 - 04:00 I 52.08425
      User Octets Received = 932
      User Octets Sent = 246
      User PDUs Received = 22
      User PDUs Sent = 10
      .
      .
      .

    The following show command displays the snapshot for the
    entity for which snapshot was activated:

    NCL> show nsp port nsp$port_0000200f all counters

    Show node 0 NSP Port NSP$PORT_0000200F
    at 1994-09-18-19:49:11.76078 - 04:00 I 52.08425

    Counters
      Creation Time = 1994-09-18-18:55:25.59899 - 04:00 I 52.08425

      Snapshot created at 1994-09-18-19:49:11.76078 - 04:00 I 52.08425

                        Actual Value    Snapshot Value    Difference
                        -------------   ---------------   ---------
  User Octets Received      2414           932            1482
  User Octets Sent          262            246              16
  User PDUs Received         25             22               3
  User PDUs Sent             11             10               1
  .                           .              .               .
  .                           .              .               .
  .                           .              .               .

    Snapshot information is only retained for the duration of an NCL
    session.  Therefore, the snapshot command and subsequent show
    commands must be issued at the NCL> prompt rather than at the
    DCL prompt.  To gather snapshot information from a remote node,
    you can either set the ncl default to the remote node entity or
    include the nodename in each ncl command, as long as the
    commands are issued within the same NCL session.