1VNSTATD(1) User Manuals VNSTATD(1)
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6 vnstatd - daemon based database updating for vnStat
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10 vnstatd [ -Ddnpsv? ] [ --alwaysadd ] [ --config file ] [ --daemon ] [
11 --debug ] [ -g group ] [ --group group ] [ --help ] [ --noadd ] [
12 --nodaemon ] [ --pidfile file ] [ --sync ] [ --u user ] [ --user user ]
13 [ --version ]
14
17 The purpose of vnstatd is to provide a more flexible and robust way for
18 updating vnstat(1) databases than what using cron for updating can pro‐
19 vide. The daemon makes possible updating databases more often but at
20 the same time causes less disk access since data can be cached and
21 written only later to disk at a user configurable interval. The avail‐
22 ability of each interface is automatically tracked which removes the
23 need for additional scripts to be implemented and called when an inter‐
24 face comes online or goes offline.
25 vnstatd is the command for starting the daemon. The daemon can either
27 fork itself to run as a background process or stay attached to the ter‐
28 minal. It supports logging to a user selectable file or using syslog.
29 Once started, the daemon will read vnstat.conf(5) if available and then
31 check if there are any databases present in the database directory that
32 has been specified in the configuration file. By default, if no data‐
33 bases are found, new databases will be created during startup for all
34 available interfaces excluding pseudo interfaces lo, lo0 and sit0. This
35 automatic database addition behaviour can be disabled using the --noadd
36 option. Alternatively, it is possible to allow the daemon to create new
37 databases whenever previously unseen interfaces become visible using
38 the --alwaysadd option.
39 The daemon will proceed to track the availability of monitored inter‐
41 faces, process the interface traffic statistics and write new values to
42 databases at a configured interval. As a result, the daemon ends up
43 spending most of the time sleeping between updates.
44
47 --alwaysadd
48 Enable automatic creation of new databases for previously unseen
49 interfaces even if the database directory already contains data‐
50 bases when the daemon is started. New databases will also get
51 created for new interfaces seen while the daemon is running.
52 Pseudo interfaces lo, lo0 and sit0 are excluded from getting
53 added.
54 --config file
57 Use file as configuration file instead of using normal configu‐
58 ration file search functionality.
59 -d, --daemon
62 Fork process to background and run as a daemon.
63 -D, --debug
66 Provide additional output for debug purposes. The process will
67 stay attached to the terminal for output.
68 -g, --group group
71 Set daemon process group to group during startup. group can be
72 either the name of the group or a numerical group id. This
73 option can only be used when the process is started as root.
74 --noadd
77 Disable automatic creation of new databases for all available
78 interfaces if the daemon is started with zero database found.
79 Pseudo interfaces lo, lo0 and sit0 are excluded from getting
80 added.
81 -n, --nodaemon
84 Stay in foreground attached to the current terminal and start
85 the update process.
86 -p, --pidfile file
89 Write the process id to file and use it for locking so that
90 another instance of the daemon cannot be started if the same
91 file is specified.
92 -s, --sync
95 Synchronize internal counters in the database with interface
96 counters for all available interfaces before starting traffic
97 monitoring. Use this option if the traffic between the previous
98 shutdown and the current startup of the daemon needs to be
99 ignored. This option isn't required in normal use because the
100 daemon will automatically synchronize the internal counters
101 after a system reboot, if enough time has passed since the dae‐
102 mon was previously running or if the internal counters are
103 clearly out of sync.
104 -u, --user user
107 Set daemon process user to user during startup. user can be
108 either the login of the user or a numerical user id. This option
109 can only be used when the process is started as root.
110 -v, --version
113 Show current version of the daemon executable.
114 -?, --help
117 Show a command option summary.
118
121 The behaviour of the daemon is configured mainly using the configura‐
122 tion keywords UpdateInterval, PollInterval and SaveInterval in the con‐
123 figuration file.
124 UpdateInterval defines in seconds how often the interface data is
127 fetched and updated. This is similar to the run interval for alterna‐
128 tive cron based updating. However, the difference is that the data
129 doesn't directly get written to disk during updates.
130 PollInterval defines in seconds how often the list of available inter‐
133 faces is checked for possible changes. The minimum value is 2 seconds
134 and the maximum 60 seconds. PollInterval also defines the resolution
135 for other intervals.
136 SaveInterval defines in minutes how often cached interface data is
139 written to disk. A write can only occur during the updating of inter‐
140 face data. Therefore, the value should be a multiple of UpdateInterval
141 with a maximum value of 60 minutes.
142 The default values of UpdateInterval 30, SaveInterval 5 and PollInter‐
145 val 5 are usually suitable for most systems and provide a similar be‐
146 haviour as cron based updating does but with a better resolution for
147 interface changes and fast interfaces.
148 For embedded and/or low power systems more tuned configurations are
151 possible. In such cases if the interfaces are mostly static the
152 PollInterval can be increased to around 10-30 seconds and UpdateInter‐
153 val set to 60 seconds. Higher values up to 300 seconds are possible if
154 the interface speed is 10 Mbit or less. SaveInterval can be increased
155 for example to 15, 30 or even 60 minutes depending on how often the
156 data needs to be viewed.
157
160 The daemon is listening to signals SIGHUP, SIGINT and SIGTERM. Sending
161 the SIGHUP signal to the daemon will cause cached data to be written to
162 disk, a rescan of the database directory and a reload of settings from
163 the configuration file. However, the pid file location will not be
164 changed even if it's configuration setting has been modified.
165 SIGTERM and SIGINT signals will cause the daemon to write all cached
168 data to disk and then exit.
169
172 /var/lib/vnstat/
173 Default database directory. Files are named according to the
174 monitored interfaces.
175 /etc/vnstat.conf
177 Config file that will be used unless $HOME/.vnstatrc exists. See
178 the configuration chapter and vnstat.conf(5) for more informa‐
179 tion.
180 /var/log/vnstat.log
182 Log file that will be used if logging to file is enable and no
183 other file is specified in the config file.
184 /var/run/vnstat.pid
186 File used for storing the process id if no other file is speci‐
187 fied in the configuration file or using the command line parame‐
188 ter.
189
192 Updates needs to be executed at least as often as it is possible for
193 the interface to generate enough traffic to overflow the kernel inter‐
194 face traffic counter. Otherwise, it is possible that some traffic won't
195 be seen. This isn't an issue for 64-bit kernels but at least one update
196 every hour is always required in order to provide proper input. With
197 32-bit kernels, the maximum time between two updates depends on how
198 fast the interface can transfer 4 GiB. Calculated theoretical times
199 are:
200 10 Mbit: 54 minutes
203 100 Mbit: 5 minutes
204 1000 Mbit: 30 seconds
205 However, for 1000 Mbit interfaces updating once every minute is usually
207 a usable solution if faster updates can't be used.
208 Virtual and aliased interfaces cannot be monitored because the kernel
210 doesn't provide traffic information for that type of interfaces. Such
211 interfaces are usually named eth0:0, eth0:1, eth0:2 etc. where eth0 is
212 the actual interface being aliased.
213
216 Teemu Toivola <tst at iki dot fi>
217
220 vnstat(1), vnstati(1), vnstat.conf(5), signal(7)
221version 1.18 MARCH 2018 VNSTATD(1)