OVS-APPCTL(8) Open vSwitch OVS-APPCTL(8)
NAME
ovs-appctl - utility for configuring running Open vSwitch daemons
SYNOPSIS
ovs-appctl [--target=target | -t target] [--timeout=secs | -T secs]
[--format=format | -f format] [--pretty] command [arg ...]
ovs-appctl --help
ovs-appctl --version
DESCRIPTION
Open vSwitch daemons accept certain commands at runtime to control
their behavior and query their settings. Every daemon accepts a common
set of commands documented under Common Commands below. Some daemons
support additional commands documented in their own manpages.
ovs-vswitchd in particular accepts a number of additional commands doc‐
umented in ovs-vswitchd(8).
The ovs-appctl program provides a simple way to invoke these commands.
The command to be sent is specified on ovs-appctl’s command line as
non-option arguments. ovs-appctl sends the command and prints the dae‐
mon’s response on standard output.
In normal use only a single option is accepted:
• -t target or --target=target
Tells ovs-appctl which daemon to contact.
If target begins with / 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 in the rundir
(e.g. /run) named <program>.<pid>.ctl, where <program> is the pro‐
gram’s name and <pid> is its process ID. For example, if
ovs-vswitchd has PID 123, it would listen on ovs-vswitchd.123.ctl.
Otherwise, ovs-appctl looks in the rundir for a pidfile, that is, a
file whose contents are the process ID of a running process as a dec‐
imal number, named target.pid. (The --pidfile option makes an Open
vSwitch daemon create a pidfile.) ovs-appctl reads the pidfile, then
looks in the rundir for a Unix socket named target.<pid>.ctl, where
<pid> is replaced by the process ID read from the pidfile, and uses
that file as if it had been specified directly as the target.
• -T secs or --timeout=secs
By default, or with a secs of 0, ovs-appctl waits forever to connect
to the daemon and receive a response. This option limits runtime to
approximately secs seconds. If the timeout expires, ovs-appctl exits
with a SIGALRM signal.
• -f format or --format=format
Tells ovs-appctl which output format to use. By default, or with a
format of text, ovs-appctl will print plain-text for humans. When
format is json, ovs-appctl will return a JSON document. When json is
requested, but a command has not implemented JSON output, the
plain-text output will be wrapped in a provisional JSON document with
the following structure:
{"reply-format":"plain","reply":"$PLAIN_TEXT_HERE"}
• --pretty
By default, JSON output is printed as compactly as possible. This
option causes JSON in output to be printed in a more readable fash‐
ion. For example, members of objects and elements of arrays are
printed one per line, with indentation. Requires --format=json.
COMMON COMMANDS
Every Open vSwitch daemon supports a common set of commands, which are
documented in this section.
General Commands
These commands display daemon-specific commands and the running ver‐
sion. Note that these commands are different from the --help and
--version options that return information about the ovs-appctl utility
itself.
• list-commands
Lists the commands supported by the target.
• version
Displays the version and compilation date of the target.
Logging Commands
Open vSwitch has several log levels. The highest-severity log level
is:
• off
No message is ever logged at this level, so setting a logging desti‐
nation’s log level to off disables logging to that destination.
The following log levels, in order of descending severity, are avail‐
able:
• emer
A major failure forced a process to abort.
• err
A high-level operation or a subsystem failed. Attention is war‐
ranted.
• warn
A low-level operation failed, but higher-level subsystems may be able
to recover.
• info
Information that may be useful in retrospect when investigating a
problem.
• dbg
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.
Every Open vSwitch daemon supports the following commands for examining
and adjusting log levels:
• vlog/list
Lists the known logging modules and their current levels.
• vlog/list-pattern
Lists logging pattern used for each destination.
• vlog/set [spec]
Sets logging levels. Without any spec, sets the log level for every
module and destination to dbg. Otherwise, spec is a list of words
separated by spaces or commas or colons, up to one from each category
below:
• A valid module name, as displayed by the vlog/list command on
ovs-appctl(8), limits the log level change to the specified module.
• syslog, console, or file, to limit the log level change to only to
the system log, to the console, or to a file, respectively.
• off, emer, err, warn, info, or dbg, to control the log level. Mes‐
sages of the given severity or higher will be logged, and messages
of lower severity will be filtered out. off filters out all mes‐
sages.
Case is not significant within spec.
Regardless of the log levels set for file, logging to a file will not
take place unless the target application was invoked with the
--log-file option.
For compatibility with older versions of OVS, any is accepted within
spec but it has no effect.
• vlog/set PATTERN:destination:pattern
Sets the log pattern for destination to pattern. Each time a message
is logged to destination, pattern determines the message’s format‐
ting. Most characters in pattern are copied literally to the log,
but special escapes beginning with % are expanded as follows:
• %A
The name of the application logging the message, e.g. ovs-vswitchd.
• %B
The RFC5424 syslog PRI of the message.
• %c
The name of the module (as shown by ovs-appctl --list) logging the
message.
• %d
The current date and time in ISO 8601 format (YYYY-MM-DD HH:MM:SS).
• %d{format}
The current date and time in the specified format, which takes the
same format as the template argument to strftime(3). As an exten‐
sion, any # characters in format will be replaced by fractional
seconds, e.g. use %H:%M:%S.### for the time to the nearest mil‐
lisecond. Sub-second times are only approximate and currently dec‐
imal places after the third will always be reported as zero.
• %D
The current UTC date and time in ISO 8601 format (YYYY-MM-DD
HH:MM:SS).
• %D{format}
The current UTC date and time in the specified format, which takes
the same format as the template argument to strftime(3). Supports
the same extension for sub-second resolution as %d{...}.
• %E
The hostname of the node running the application.
• %m
The message being logged.
• %N
A serial number for this message within this run of the program, as
a decimal number. The first message a program logs has serial num‐
ber 1, the second one has serial number 2, and so on.
• %n
A new-line.
• %p
The level at which the message is logged, e.g. DBG.
• %P
The program’s process ID (pid), as a decimal number.
• %r
The number of milliseconds elapsed from the start of the applica‐
tion to the time the message was logged.
• %t
The subprogram name, that is, an identifying name for the process
or thread that emitted the log message, such as monitor for the
process used for --monitor or main for the primary process or
thread in a program.
• %T
The subprogram name enclosed in parentheses, e.g. (monitor), or the
empty string for the primary process or thread in a program.
• %%
A literal %.
A few options may appear between the % and the format specifier char‐
acter, in this order:
• -
Left justify the escape’s expansion within its field width. Right
justification is the default.
• 0
Pad the field to the field width with 0 characters. Padding with
spaces is the default.
• width
A number specifies the minimum field width. If the escape expands
to fewer characters than width then it is padded to fill the field
width. (A field wider than width is not truncated to fit.)
The default pattern for console and file output is %D{%Y-%m-%dT
%H:%M:%SZ}|%05N|%c|%p|%m; for syslog output, %05N|%c|%p|%m.
Daemons written in Python (e.g. ovs-monitor-ipsec) do not allow con‐
trol over the log pattern.
• vlog/set FACILITY:facility
Sets the RFC5424 facility of the log message. facility can be one of
kern, user, mail, daemon, auth, syslog, lpr, news, uucp, clock, ftp,
ntp, audit, alert, clock2, local0, local1, local2, local3, local4,
local5, local6 or local7.
• vlog/close
Causes the daemon to close its log file, if it is open. (Use
vlog/reopen to reopen it later.)
• vlog/reopen
Causes the daemon to close its log file, if it is open, and then re‐
open it. (This is useful after rotating log files, to cause a new
log file to be used.)
This has no effect if the target application was not invoked with the
--log-file option.
OPTIONS
-h, --help
Prints a brief help message to the console.
-V, --version
Prints version information to the console.
SEE ALSO
ovs-appctl can control all Open vSwitch daemons, including
ovs-vswitchd(8) and ovsdb-server(1).
AUTHOR
The Open vSwitch Development Community
COPYRIGHT
2016-2024, The Open vSwitch Development Community
4.0 Aug 17, 2026 OVS-APPCTL(8)