+The \fBovs\-appctl\fR program provides a simple way to invoke these
+commands. The command to be sent is specified on \fBovs\-appctl\fR's
+command line as non-option arguments. \fBovs\-appctl\fR sends the
+command and prints the daemon's response on standard output.
+.PP
+In normal use only a single option is accepted:
+.IP "\fB\-t \fItarget\fR"
+.IQ "\fB\-\-target=\fItarget\fR"
+Tells \fBovs\-appctl\fR which daemon to contact.
+.IP
+If \fItarget\fR begins with \fB/\fR it must name a Unix domain socket
+on which an Open vSwitch daemon is listening for control channel
+connections. By default, each daemon listens on a Unix domain socket
+named \fB@RUNDIR@/\fIprogram\fB.\fIpid\fB.ctl\fR, where \fIprogram\fR
+is the program's name and \fIpid\fR is its process ID. For example,
+if \fBovs\-vswitchd\fR has PID 123, it would listen on
+\fB@RUNDIR@/ovs\-vswitchd.123.ctl\fR.
+.IP
+Otherwise, \fBovs\-appctl\fR looks for a pidfile, that is, a file
+whose contents are the process ID of a running process as a decimal
+number, named \fB@RUNDIR@/\fItarget\fB.pid\fR. (The \fB\-\-pidfile\fR
+option makes an Open vSwitch daemon create a pidfile.)
+\fBovs\-appctl\fR reads the pidfile, then looks for a Unix socket
+named \fB@RUNDIR@/\fItarget\fB.\fIpid\fB.ctl\fR, where \fIpid\fR is
+replaced by the process ID read from the pidfile, and uses that file
+as if it had been specified directly as the target.
+.IP
+The default target is \fBovs\-vswitchd\fR.
+.
+.SH COMMON COMMANDS
+Every Open vSwitch daemon supports a common set of commands, which are
+documented in this section.
+.
+.SS GENERAL COMMANDS
+These commands display daemon-specific commands and the running version.
+Note that these commands are different from the \fB\-\-help\fR and
+\fB\-\-version\fR options that return information about the
+\fBovs\-appctl\fR utility itself.
+.
+.IP "\fBhelp\fR"
+Lists the commands supported by the target.
+.
+.IP "\fBversion\fR"
+Displays the version and compilation date of the target.
+.
+.SS LOGGING COMMANDS
+Open vSwitch has several log levels. The highest-severity log level is:
+.
+.IP "\fBOFF\fR"
+No message is ever logged at this level, so setting a logging
+facility's log level to \fBOFF\fR disables logging to that facility.
+.
+.PP
+The following log levels, in order of descending severity, are
+available:
+.
+.IP "\fBEMER\fR"
+A major failure forced a process to abort.
+.IP "\fBERR\fR"
+A high-level operation or a subsystem failed. Attention is
+warranted.
+.IP "\fBWARN\fR"
+A low-level operation failed, but higher-level subsystems may be able
+to recover.
+.IP "\fBINFO\fR"
+Information that may be useful in retrospect when investigating
+a problem.
+.IP "\fBDBG\fR"
+Information useful only to someone with intricate knowledge of the
+system, or that would commonly cause too-voluminous log output. Log
+messages at this level are not logged by default.
+.
+.PP
+Every Open vSwitch daemon supports the following commands for examining
+and adjusting log levels.
+.IP "\fBvlog/list\fR"
+Lists the known logging modules and their current levels.
+.
+.IP "\fBvlog/set\fR \fImodule\fR[\fB:\fIfacility\fR[\fB:\fIlevel\fR]]"