Ubuntu Manpage: vnstatd - daemon based database updating for vnStat

NAME

       vnstatd - daemon based database updating for vnStat

SYNOPSIS

       vnstatd [-Ddnpsv?]  [--alwaysadd] [--config file] [--daemon] [--debug] [-g group] [--group
       group] [--help] [--noadd] [--nodaemon] [--pidfile file] [--sync] [--u user] [--user  user]
       [--version]

DESCRIPTION

The purpose of vnstatd is to provide a flexible and robust way for updating the database
that vnstat(1) uses. The availability of each interface is automatically tracked which
removes the need for additional scripts to be implemented and called when an interface
comes online or goes offline.

vnstatd is the command for starting the daemon. The daemon can either fork itself to run
as a background process or stay attached to the terminal. It supports logging to a user
selectable file or using syslog.

Once started, the daemon will read vnstat.conf(5) if available and then check if there is
a database present in the database directory that has been specified in the configuration
file. By default, if no database is found, a database will be created during startup with
entries for all available interfaces excluding pseudo interfaces lo, lo0 and sit0. This
automatic database entry creation behaviour can be disabled using the --noadd option.
Alternatively, it is possible to allow the daemon to create new database entries whenever
previously unseen interfaces become visible using the --alwaysadd option.

The daemon will proceed to track the availability of monitored interfaces, process the
interface traffic statistics and write new values to the database at a configured
interval. As a result, the daemon ends up spending most of the time sleeping between
updates.

OPTIONS

--alwaysadd
Enable automatic creation of new database entries for previously unseen interfaces
even if the database directory already contains a database when the daemon is
started. New database entries will also get created for new interfaces seen while
the daemon is running. Pseudo interfaces lo, lo0 and sit0 are excluded from getting
added.

--config file
Use file as configuration file instead of using automatic configuration file search
functionality.

-d, --daemon
Fork process to background and run as a daemon.

-D, --debug
Provide additional output for debug purposes. The process will stay attached to the
terminal for output.

-g, --group group
Set daemon process group to group during startup. group can be either the name of
the group or a numerical group id. This option can only be used when the process is
started as root.

--noadd
Disable automatic creation of new database entries for all available interfaces if
the daemon is started with no database found. Pseudo interfaces lo, lo0 and sit0
are excluded from getting added.

-n, --nodaemon
Stay in foreground attached to the current terminal and start the update process.

-p, --pidfile file
Write the process id to file and use it for locking so that another instance of the
daemon cannot be started if the same file is specified.

-s, --sync
Synchronize internal counters in the database with interface counters for all
available interfaces before starting traffic monitoring. Use this option if the
traffic between the previous shutdown and the current startup of the daemon needs
to be ignored. This option isn't required in normal use because the daemon will
automatically synchronize the internal counters after a system reboot, if enough
time has passed since the daemon was previously running or if the internal counters
are clearly out of sync.

-u, --user user
Set daemon process user to user during startup. user can be either the login of
the user or a numerical user id. This option can only be used when the process is
started as root.

-v, --version
Show current version of the daemon executable.

-?, --help
Show a command option summary.

CONFIGURATION

The behaviour of the daemon is configured mainly using the configuration keywords
UpdateInterval, PollInterval and SaveInterval in the configuration file.

UpdateInterval defines in seconds how often the interface data is fetched and updated.
This is similar to the run interval for alternative cron based updating. However, the
difference is that the data doesn't directly get written to disk during updates.

PollInterval defines in seconds how often the list of available interfaces is checked for
possible changes. The minimum value is 2 seconds and the maximum 60 seconds. PollInterval
also defines the resolution for other intervals.

SaveInterval defines in minutes how often cached interface data is written to disk. A
write can only occur during the updating of interface data. Therefore, the value should be
a multiple of UpdateInterval with a maximum value of 60 minutes.

The default values of UpdateInterval 30, SaveInterval 5 and PollInterval 5 are usually
suitable for most systems and provide a similar behaviour as cron based updating does but
with a better resolution for interface changes and fast interfaces.

For embedded and/or low power systems more tuned configurations are possible. In such
cases if the interfaces are mostly static the PollInterval can be increased to around
10-30 seconds and UpdateInterval set to 60 seconds. Higher values up to 300 seconds are
possible if the interface speed is 10 Mbit or less. SaveInterval can be increased for
example to 15, 30 or even 60 minutes depending on how often the data needs to be viewed.

SIGNALS

       The  daemon is listening to signals SIGHUP, SIGINT and SIGTERM.  Sending the SIGHUP signal
       to the daemon will cause cached data to be written to  disk,  a  rescan  of  the  database
       directory  and  a  reload  of  settings from the configuration file. However, the pid file
       location will not be changed even if it's configuration setting has been modified.

       SIGTERM and SIGINT signals will cause the daemon to write all cached data to disk and then
       exit.

FILES

       /var/lib/vnstat/
              Default database directory.

       /etc/vnstat.conf
              Config  file that will be used unless $HOME/.vnstatrc exists. See the configuration
              chapter and vnstat.conf(5) for more information.

       /var/log/vnstat.log
              Log file that will be used if logging to file  is  enable  and  no  other  file  is
              specified in the config file.

       /run/vnstat.pid
              File  used  for  storing  the  process  id  if  no  other  file is specified in the
              configuration file or using the command line parameter.

RESTRICTIONS

       Updates need to be executed at least as often as it  is  possible  for  the  interface  to
       generate enough traffic to overflow the kernel interface traffic counter. Otherwise, it is
       possible that some traffic won't be seen. With 32-bit kernels, the  maximum  time  between
       two  updates  depends on how fast the interface can transfer 4 GiB. Calculated theoretical
       times are:

              10 Mbit:        54 minutes
              100 Mbit:        5 minutes
              1000 Mbit:      30 seconds

       However, for 1000 Mbit interfaces updating once every minute is usually a usable  solution
       if a shorter update interval can't be used.

       Virtual  and  aliased  interfaces  cannot  be monitored because the kernel doesn't provide
       traffic information for that type of interfaces. Such interfaces are usually named eth0:0,
       eth0:1, eth0:2 etc. where eth0 is the actual interface being aliased.

AUTHOR

       Teemu Toivola <tst at iki dot fi>