symon/symon/symon/symon.8

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.Dd April 5, 2002
.Dt SYMON 8
.Os
.Sh NAME
.Nm symon
.Nd system monitor
.Sh SYNOPSIS
.Nm
.Op Fl duv
.Op Fl f Ar filename
.Pp
.Sh DESCRIPTION
.Nm
is a lightweight system monitor that measures cpu, memory, debug,
process, interface and disk statistics every 5 seconds. This information
is then spooled to
.Xr symux 8
for further processing.
.Pp
.Nm
has been designed to inflict minimal performance and security impact on
the system it monitors.
.Xr symux 8
has performance impact proportional to the amount of streams it needs to
manage. Ideally
.Xr symux
should live on a different system and collect data from several
.Nm
instances in a LAN.
.Lp
By default,
.Nm
will drop priviledges and chroot(2) to home of
.Ar "_symon".
This behaviour is not strictly needed for the cpu, mem, mbuf, disk debug and
interface probes as these will work even when
.Nm
is started as
.Ar "nobody".
.Lp
The options:
.Bl -tag -width Ds
.It Fl d
Stop
.Nm
from becoming a daemon and show debug information on stdout.
.It Fl f Ar filename
Read configuration from
.Ar filename
instead of
.Pa /etc/symon.conf .
.It Fl u
By default
.Nm
will chroot(2) into
.Pa _symon
user home directory. The
.Pa -u
disables this behaviour.
.It Fl v
Show version information.
.El
.Sh CONFIGURATION
.Nm
obtains configuration data from
.Pa /etc/symon.conf .
The configuration file contains monitor stanzas that define what
resources should be monitored and to which
.Xr symux 8
the information should be streamed to.
.Pp
Multiple monitor statements to different muxes are allowed. Whitespace,
newlines and text behind '#' are ignored. The format in BNF:
.Pp
.nf
monitor-rule = "monitor" "{" resources "}" [every]
	       "stream" ["to"] host [ port ]
resources    = resource ["(" argument ")"] [ ","|" " resources ]
argument     = number | interfacename | diskname
resource     = "cpu" | "mem" | "if" | "io" | "pf" | "debug" |
	       "proc" | "mbuf" | "sensor"
every        = "every" "second" | number "seconds"
host         = ip4addr | ip6addr | hostname
port         = [ "port" | "," ] portnumber
.fi
.Pp
Note that symux(8) data files default to receiving data every 5
seconds. Adjusting the monitoring interval will also require adjusting every
symux(8) datafile.
.Sh EXAMPLE
Here is an example
.Ar symon.conf
that monitors cpu, memory, pf, interfaces xl0/de0/lo0/wi0, disks
wd[0-3]/cd[0-1], debug variables debug0 to debug19 and streams that
information to localhost on port 2100.
.Pp
.nf
monitor { cpu(0),  mem, pf, if(xl0), if(de0),
	  if(lo0), if(wi0), io(wd0), io(wd1),
	  io(wd2), io(wd3), io(cd0), io(cd1),
	  io(ccd0), debug, proc(httpd) } stream to 127.0.0.1 2100
.fi
.Sh SIGNALS
.Bl -tag -width Ds
.It SIGHUP
Causes
.Nm
to read
.Pa /etc/symon.conf .
.Nm
will keep the old configuration if errors occured during parsing of the
configuration file. Note that the chroot(2) may cause resources to become
unattainable, most notably the configuration file itself.
.Sh FILES
.Bl -tag -width Ds
.It Pa /var/run/symon.pid
Contains the program id of the
.Nm
daemon.
.It Pa /etc/symon.conf
.Nm
system wide configuration file.
.El
.Sh BUGS
Every monitored resource mentioned
.Pa /etc/symon.conf
gets queried. Mentioning, for example, cpu(0) twice for different muxes will
result in two distinct cpu(0) measurement actions.
.Pp
The proc module is too simple: memory shared between two instances of the same
process is simply counted twice.
.Pp
.Nm
does not check whether resources mentioned in
.Pa /etc/symon.conf
exist.
.Pp
.Sh AUTHOR
Willem Dijkstra <wpd@xs4all.nl>. Daniel Hartmeier <daniel@benzedrine.cx>
contributed the pf probe and helped to port to big-endian architectures.
.Sh SEE ALSO
.Xr symux 8