Provided by: ovn-common_2.9.8-0ubuntu0.18.04.5_amd64 

NAME
ovn-sbctl - utility for querying and configuring OVN_Southbound database
SYNOPSIS
ovn-sbctl [options] -- [options] command [args] [-- [options] command [args]]...
DESCRIPTION
The ovn-sbctl program configures the OVN_Southbound database by providing a high-level interface to its
configuration database. See ovn-sb(5) for comprehensive documentation of the database schema.
ovn-sbctl connects to an ovsdb-server process that maintains an OVN_Southbound configuration database.
Using this connection, it queries and possibly applies changes to the database, depending on the supplied
commands.
ovn-sbctl can perform any number of commands in a single run, implemented as a single atomic transaction
against the database.
The ovn-sbctl command line begins with global options (see OPTIONS below for details). The global
options are followed by one or more commands. Each command should begin with -- by itself as a command-
line argument, to separate it from the following commands. (The -- before the first command is
optional.) The command itself starts with command-specific options, if any, followed by the command name
and any arguments.
OPTIONS
The following options affect the behavior of ovn-sbctl as a whole. Some individual commands also accept
their own options, which are given just before the command name. If the first command on the command
line has options, then those options must be separated from the global options by --.
--db=server
The OVSDB database remote to contact. If the OVN_SB_DB environment variable is set, its value is
used as the default. Otherwise, the default is unix:/var/run/openvswitch/ovnsb_db.sock, but this
default is unlikely to be useful outside of single-machine OVN test environments.
server may be an OVSDB active or passive connection method, e.g. ssl:192.168.10.5:6640, as
described in ovsdb(7).
--leader-only
--no-leader-only
By default, or with --leader-only, when the database server is a clustered database, ovn-sbctl
will avoid servers other than the cluster leader. This ensures that any data that ovn-sbctl reads
and reports is up-to-date. With --no-leader-only, ovn-sbctl will use any server in the cluster,
which means that for read-only transactions it can report and act on stale data (transactions that
modify the database are always serialized even with --no-leader-only). Refer to Understanding
Cluster Consistency in ovsdb(7) for more information.
--no-syslog
By default, ovn-sbctl logs its arguments and the details of any changes that it makes to the
system log. This option disables this logging.
This option is equivalent to --verbose=sbctl:syslog:warn.
--oneline
Modifies the output format so that the output for each command is printed on a single line. New-
line characters that would otherwise separate lines are printed as \n, and any instances of \ that
would otherwise appear in the output are doubled. Prints a blank line for each command that has
no output. This option does not affect the formatting of output from the list or find commands;
see Table Formatting Options below.
--dry-run
Prevents ovn-sbctl from actually modifying the database.
-t secs
--timeout=secs
By default, or with a secs of 0, ovn-sbctl waits forever for a response from the database. This
option limits runtime to approximately secs seconds. If the timeout expires, ovn-sbctl will exit
with a SIGALRM signal. (A timeout would normally happen only if the database cannot be contacted,
or if the system is overloaded.)
-v[spec]
--verbose=[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. (If --detach is specified, ovn-sbctl closes its
standard file descriptors, so logging to the console will have no effect.)
On Windows platform, syslog is accepted as a word and is only useful along with the
--syslog-target option (the word has no effect otherwise).
• off, emer, err, warn, info, or dbg, to control the log level. Messages of the given
severity or higher will be logged, and messages of lower severity will be filtered out.
off filters out all messages. See ovs-appctl(8) for a definition of each log level.
Case is not significant within spec.
Regardless of the log levels set for file, logging to a file will not take place unless --log-file
is also specified (see below).
For compatibility with older versions of OVS, any is accepted as a word but has no effect.
-v
--verbose
Sets the maximum logging verbosity level, equivalent to --verbose=dbg.
-vPATTERN:destination:pattern
--verbose=PATTERN:destination:pattern
Sets the log pattern for destination to pattern. Refer to ovs-appctl(8) for a description of the
valid syntax for pattern.
-vFACILITY:facility
--verbose=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. If this option is not specified, daemon is used as the
default for the local system syslog and local0 is used while sending a message to the target
provided via the --syslog-target option.
--log-file[=file]
Enables logging to a file. If file is specified, then it is used as the exact name for the log
file. The default log file name used if file is omitted is /var/log/openvswitch/ovn-sbctl.log.
--syslog-target=host:port
Send syslog messages to UDP port on host, in addition to the system syslog. The host must be a
numerical IP address, not a hostname.
--syslog-method=method
Specify method how syslog messages should be sent to syslog daemon. Following forms are
supported:
• libc, use libc syslog() function. This is the default behavior. Downside of using this
options is that libc adds fixed prefix to every message before it is actually sent to the
syslog daemon over /dev/log UNIX domain socket.
• unix:file, use UNIX domain socket directly. It is possible to specify arbitrary message
format with this option. However, rsyslogd 8.9 and older versions use hard coded parser
function anyway that limits UNIX domain socket use. If you want to use arbitrary message
format with older rsyslogd versions, then use UDP socket to localhost IP address instead.
• udp:ip:port, use UDP socket. With this method it is possible to use arbitrary message
format also with older rsyslogd. When sending syslog messages over UDP socket extra
precaution needs to be taken into account, for example, syslog daemon needs to be
configured to listen on the specified UDP port, accidental iptables rules could be
interfering with local syslog traffic and there are some security considerations that apply
to UDP sockets, but do not apply to UNIX domain sockets.
-h
--help Prints a brief help message to the console.
-V
--version
Prints version information to the console.
Table Formatting Options
These options control the format of output from the list and find commands.
-f format
--format=format
Sets the type of table formatting. The following types of format are available:
table 2-D text tables with aligned columns.
list (default)
A list with one column per line and rows separated by a blank line.
html HTML tables.
csv Comma-separated values as defined in RFC 4180.
json JSON format as defined in RFC 4627. The output is a sequence of JSON objects, each of
which corresponds to one table. Each JSON object has the following members with the noted
values:
caption
The table's caption. This member is omitted if the table has no caption.
headings
An array with one element per table column. Each array element is a string giving
the corresponding column's heading.
data An array with one element per table row. Each element is also an array with one
element per table column. The elements of this second-level array are the cells
that constitute the table. Cells that represent OVSDB data or data types are
expressed in the format described in the OVSDB specification; other cells are simply
expressed as text strings.
-d format
--data=format
Sets the formatting for cells within output tables unless the table format is set to json, in
which case json formatting is always used when formatting cells. The following types of format
are available:
string (default)
The simple format described in the Database Values section of ovs-vsctl(8).
bare The simple format with punctuation stripped off: [] and {} are omitted around sets, maps,
and empty columns, items within sets and maps are space-separated, and strings are never
quoted. This format may be easier for scripts to parse.
json The RFC 4627 JSON format as described above.
--no-headings
This option suppresses the heading row that otherwise appears in the first row of table output.
--pretty
By default, JSON in output is printed as compactly as possible. This option causes JSON in output
to be printed in a more readable fashion. Members of objects and elements of arrays are printed
one per line, with indentation.
This option does not affect JSON in tables, which is always printed compactly.
--bare Equivalent to --format=list --data=bare --no-headings.
--max-column-width=n
For table output only, limits the width of any column in the output to n columns. Longer cell
data is truncated to fit, as necessary. Columns are always wide enough to display the column
names, if the heading row is printed.
Public Key Infrastructure Options
-p privkey.pem
--private-key=privkey.pem
Specifies a PEM file containing the private key used as ovn-sbctl's identity for outgoing SSL
connections.
-c cert.pem
--certificate=cert.pem
Specifies a PEM file containing a certificate that certifies the private key specified on -p or
--private-key to be trustworthy. The certificate must be signed by the certificate authority (CA)
that the peer in SSL connections will use to verify it.
-C cacert.pem
--ca-cert=cacert.pem
Specifies a PEM file containing the CA certificate that ovn-sbctl should use to verify
certificates presented to it by SSL peers. (This may be the same certificate that SSL peers use
to verify the certificate specified on -c or --certificate, or it may be a different one,
depending on the PKI design in use.)
-C none
--ca-cert=none
Disables verification of certificates presented by SSL peers. This introduces a security risk,
because it means that certificates cannot be verified to be those of known trusted hosts.
--bootstrap-ca-cert=cacert.pem
When cacert.pem exists, this option has the same effect as -C or --ca-cert. If it does not exist,
then ovn-sbctl will attempt to obtain the CA certificate from the SSL peer on its first SSL
connection and save it to the named PEM file. If it is successful, it will immediately drop the
connection and reconnect, and from then on all SSL connections must be authenticated by a
certificate signed by the CA certificate thus obtained.
This option exposes the SSL connection to a man-in-the-middle attack obtaining the initial CA
certificate, but it may be useful for bootstrapping.
This option is only useful if the SSL peer sends its CA certificate as part of the SSL certificate
chain. The SSL protocol does not require the server to send the CA certificate.
This option is mutually exclusive with -C and --ca-cert.
--peer-ca-cert=peer-cacert.pem
Specifies a PEM file that contains one or more additional certificates to send to SSL peers.
peer-cacert.pem should be the CA certificate used to sign ovn-sbctl's own certificate, that is,
the certificate specified on -c or --certificate. If ovn-sbctl's certificate is self-signed, then
--certificate and --peer-ca-cert should specify the same file.
This option is not useful in normal operation, because the SSL peer must already have the CA
certificate for the peer to have any confidence in ovn-sbctl's identity. However, this offers a
way for a new installation to bootstrap the CA certificate on its first SSL connection.
COMMANDS
The commands implemented by ovn-sbctl are described in the sections below.
OVN_Southbound Commands
These commands work with an OVN_Southbound database as a whole.
init Initializes the database, if it is empty. If the database has already been initialized, this
command has no effect.
show Prints a brief overview of the database contents.
Chassis Commands
These commands manipulate OVN_Southbound chassis.
[--may-exist] chassis-add chassis encap-type encap-ip
Creates a new chassis named chassis. encap-type is a comma-separated list of tunnel types. The
chassis will have one encap entry for each specified tunnel type with encap-ip as the destination
IP for each.
Without --may-exist, attempting to create a chassis that exists is an error. With --may-exist,
this command does nothing if chassis already exists.
[--if-exists] chassis-del chassis
Deletes chassis and its encaps and gateway_ports.
Without --if-exists, attempting to delete a chassis that does not exist is an error. With
--if-exists, attempting to delete a chassis that does not exist has no effect.
Port binding Commands
These commands manipulate OVN_Southbound port bindings.
[--may-exist] lsp-bind logical-port chassis
Binds the logical port named logical-port to chassis.
Without --may-exist, attempting to bind a logical port that has already been bound is an error.
With --may-exist, this command does nothing if logical-port has already been bound to a chassis.
[--if-exists] lsp-unbind logical-port
Resets the binding of logical-port to NULL.
Without --if-exists, attempting to unbind a logical port that is not bound is an error. With
--if-exists, attempting to unbind logical port that is not bound has no effect.
Logical Flow Commands
[--uuid] [--ovs[=remote]] [--stats] lflow-list [logical-datapath] [lflow...]
List logical flows. If logical-datapath is specified, only list flows for that logical datapath.
The logical-datapath may be given as a UUID or as a datapath name (reporting an error if multiple
datapaths have the same name).
If at least one lflow is given, only matching logical flows, if any, are listed. Each lflow may
be specified as a UUID or the first few characters of a UUID, optionally prefixed by 0x. (Because
ovn-controller sets OpenFlow flow cookies to the first 32 bits of the corresponding logical flow's
UUID, this makes it easy to look up the logical flow that generated a particular OpenFlow flow.)
If --uuid is specified, the output includes the first 32 bits of each logical flow's UUID. This
makes it easier to find the OpenFlow flows that correspond to a given logical flow.
If --ovs is included, ovn-sbctl attempts to obtain and display the OpenFlow flows that correspond
to each OVN logical flow. To do so, ovn-sbctl connects to remote (by default,
unix:/var/run/openvswitch/br-int.mgmt) over OpenFlow and retrieves the flows. If remote is
specified, it must be an active OpenFlow connection method described in ovs-ofctl(8). Please see
the discussion of the similar --ovs option in ovn-trace(8) for more information about the OpenFlow
flow output.
By default, OpenFlow flow output includes only match and actions. Add --stats to include all
OpenFlow information, such as packet and byte counters, duration, and timeouts.
[--uuid] dump-flows [logical-datapath]
Alias for lflow-list.
Remote Connectivity Commands
These commands manipulate the connections column in the SB_Global table and rows in the Connection table.
When ovsdb-server is configured to use the connections column for OVSDB connections, this allows the
administrator to use ovn-sbctl to configure database connections.
get-connection
Prints the configured connection(s).
del-connection
Deletes the configured connection(s).
set-connection [access-specifier] target...
Sets the configured manager target or targets. Each target may may be an OVSDB active or passive
connection method, e.g. pssl:6640, as described in ovsdb(7), optionally preceded by an optional
access-specifier (read-only or read-write). If provided, the effect of the access specifier
persists for subsequent targets until changed by another access specifier.
SSL Configuration
When ovsdb-server is configured to connect using SSL, the following parameters are required:
private-key
Specifies a PEM file containing the private key used for SSL connections.
certificate
Specifies a PEM file containing a certificate, signed by the certificate authority (CA) used by
the connection peers, that certifies the private key, identifying a trustworthy peer.
ca-cert
Specifies a PEM file containing the CA certificate used to verify that the connection peers are
trustworthy.
These SSL settings apply to all SSL connections made by the southbound database server.
get-ssl
Prints the SSL configuration.
del-ssl
Deletes the current SSL configuration.
[--bootstrap] set-ssl private-key certificate ca-cert [ssl-protocol-list [ssl-cipher-list]]
Sets the SSL configuration. The --bootstrap option is described below.
CA Certificate Bootstrap
Ordinarily, all of the files named in the SSL configuration must exist before SSL connectivity can be
used. However, if the ca-cert file does not exist and the --bootstrap option is given, then ovsdb-server
will attempt to obtain the CA certificate from the target on its first SSL connection and save it to the
named PEM file. If it is successful, it will immediately drop the connection and reconnect, and from
then on all SSL connections must be authenticated by a certificate signed by the CA certificate thus
obtained.
This option exposes the SSL connection to a man-in-the-middle attack obtaining the initial CA
certificate, but it may be useful for bootstrapping.
This option is only useful if the SSL peer sends its CA certificate as part of the SSL certificate chain.
The SSL protocol does not require the controller to send the CA certificate.
Database Commands
These commands query and modify the contents of ovsdb tables. They are a slight abstraction of the ovsdb
interface and as such they operate at a lower level than other ovs-sbctl commands.
Identifying Tables, Records, and Columns
Each of these commands has a table parameter to identify a table within the database. Many of them also
take a record parameter that identifies a particular record within a table. The record parameter may be
the UUID for a record, and many tables offer additional ways to identify records. Some commands also
take column parameters that identify a particular field within the records in a table.
For a list of tables and their columns, see ovn-sb(5) or see the table listing from the --help option.
Record names must be specified in full and with correct capitalization, except that UUIDs may be
abbreviated to their first 4 (or more) hex digits, as long as that is unique within the table. Names of
tables and columns are not case-sensitive, and - and _ are treated interchangeably. Unique abbreviations
of table and column names are acceptable, e.g. addr or a is sufficient to identify the Address_Set table.
Database Values
Each column in the database accepts a fixed type of data. The currently defined basic types, and their
representations, are:
integer
A decimal integer in the range -2**63 to 2**63-1, inclusive.
real A floating-point number.
Boolean
True or false, written true or false, respectively.
string An arbitrary Unicode string, except that null bytes are not allowed. Quotes are optional for most
strings that begin with an English letter or underscore and consist only of letters, underscores,
hyphens, and periods. However, true and false and strings that match the syntax of UUIDs (see
below) must be enclosed in double quotes to distinguish them from other basic types. When double
quotes are used, the syntax is that of strings in JSON, e.g. backslashes may be used to escape
special characters. The empty string must be represented as a pair of double quotes ("").
UUID Either a universally unique identifier in the style of RFC 4122, e.g.
f81d4fae-7dec-11d0-a765-00a0c91e6bf6, or an @name defined by a get or create command within the
same ovn-sbctl invocation.
Multiple values in a single column may be separated by spaces or a single comma. When multiple values
are present, duplicates are not allowed, and order is not important. Conversely, some database columns
can have an empty set of values, represented as [], and square brackets may optionally enclose other non-
empty sets or single values as well. For a column accepting a set of integers, database commands accept a
range. A range is represented by two integers separated by -. A range is inclusive. A range has a maximum
size of 4096 elements. If more elements are needed, they can be specified in seperate ranges.
A few database columns are ``maps'' of key-value pairs, where the key and the value are each some fixed
database type. These are specified in the form key=value, where key and value follow the syntax for the
column's key type and value type, respectively. When multiple pairs are present (separated by spaces or
a comma), duplicate keys are not allowed, and again the order is not important. Duplicate values are
allowed. An empty map is represented as {}. Curly braces may optionally enclose non-empty maps as well
(but use quotes to prevent the shell from expanding other-config={0=x,1=y} into other-config=0=x other-
config=1=y, which may not have the desired effect).
Database Command Syntax
[--if-exists] [--columns=column[,column]...] list table [record]...
Lists the data in each specified record. If no records are specified, lists all the records in
table.
If --columns is specified, only the requested columns are listed, in the specified order.
Otherwise, all columns are listed, in alphabetical order by column name.
Without --if-exists, it is an error if any specified record does not exist. With --if-exists, the
command ignores any record that does not exist, without producing any output.
[--columns=column[,column]...] find table [column[:key]=value]...
Lists the data in each record in table whose column equals value or, if key is specified, whose
column contains a key with the specified value. The following operators may be used where = is
written in the syntax summary:
= != < > <= >=
Selects records in which column[:key] equals, does not equal, is less than, is greater
than, is less than or equal to, or is greater than or equal to value, respectively.
Consider column[:key] and value as sets of elements. Identical sets are considered equal.
Otherwise, if the sets have different numbers of elements, then the set with more elements
is considered to be larger. Otherwise, consider a element from each set pairwise, in
increasing order within each set. The first pair that differs determines the result. (For
a column that contains key-value pairs, first all the keys are compared, and values are
considered only if the two sets contain identical keys.)
{=} {!=}
Test for set equality or inequality, respectively.
{<=} Selects records in which column[:key] is a subset of value. For example, flood-
vlans{<=}1,2 selects records in which the flood-vlans column is the empty set or contains 1
or 2 or both.
{<} Selects records in which column[:key] is a proper subset of value. For example, flood-
vlans{<}1,2 selects records in which the flood-vlans column is the empty set or contains 1
or 2 but not both.
{>=} {>}
Same as {<=} and {<}, respectively, except that the relationship is reversed. For example,
flood-vlans{>=}1,2 selects records in which the flood-vlans column contains both 1 and 2.
For arithmetic operators (= != < > <= >=), when key is specified but a particular record's column
does not contain key, the record is always omitted from the results. Thus, the condition other-
config:mtu!=1500 matches records that have a mtu key whose value is not 1500, but not those that
lack an mtu key.
For the set operators, when key is specified but a particular record's column does not contain
key, the comparison is done against an empty set. Thus, the condition other-config:mtu{!=}1500
matches records that have a mtu key whose value is not 1500 and those that lack an mtu key.
Don't forget to escape < or > from interpretation by the shell.
If --columns is specified, only the requested columns are listed, in the specified order.
Otherwise all columns are listed, in alphabetical order by column name.
The UUIDs shown for rows created in the same ovn-sbctl invocation will be wrong.
[--if-exists] [--id=@name] get table record [column[:key]]...
Prints the value of each specified column in the given record in table. For map columns, a key
may optionally be specified, in which case the value associated with key in the column is printed,
instead of the entire map.
Without --if-exists, it is an error if record does not exist or key is specified, if key does not
exist in record. With --if-exists, a missing record yields no output and a missing key prints a
blank line.
If @name is specified, then the UUID for record may be referred to by that name later in the same
ovn-sbctl invocation in contexts where a UUID is expected.
Both --id and the column arguments are optional, but usually at least one or the other should be
specified. If both are omitted, then get has no effect except to verify that record exists in
table.
--id and --if-exists cannot be used together.
[--if-exists] set table record column[:key]=value...
Sets the value of each specified column in the given record in table to value. For map columns, a
key may optionally be specified, in which case the value associated with key in that column is
changed (or added, if none exists), instead of the entire map.
Without --if-exists, it is an error if record does not exist. With --if-exists, this command does
nothing if record does not exist.
[--if-exists] add table record column [key=]value...
Adds the specified value or key-value pair to column in record in table. If column is a map, then
key is required, otherwise it is prohibited. If key already exists in a map column, then the
current value is not replaced (use the set command to replace an existing value).
Without --if-exists, it is an error if record does not exist. With --if-exists, this command does
nothing if record does not exist.
[--if-exists] remove table record column value...
[--if-exists] remove table record column key...
[--if-exists] remove table record column key=value...
Removes the specified values or key-value pairs from column in record in table. The first form
applies to columns that are not maps: each specified value is removed from the column. The second
and third forms apply to map columns: if only a key is specified, then any key-value pair with the
given key is removed, regardless of its value; if a value is given then a pair is removed only if
both key and value match.
It is not an error if the column does not contain the specified key or value or pair.
Without --if-exists, it is an error if record does not exist. With --if-exists, this command does
nothing if record does not exist.
[--if-exists] clear table record column...
Sets each column in record in table to the empty set or empty map, as appropriate. This command
applies only to columns that are allowed to be empty.
Without --if-exists, it is an error if record does not exist. With --if-exists, this command does
nothing if record does not exist.
[--id=@name] create table column[:key]=value...
Creates a new record in table and sets the initial values of each column. Columns not explicitly
set will receive their default values. Outputs the UUID of the new row.
If @name is specified, then the UUID for the new row may be referred to by that name elsewhere in
the same ovn-sbctl invocation in contexts where a UUID is expected. Such references may precede
or follow the create command.
Caution (ovs-vsctl as example)
Records in the Open vSwitch database are significant only when they can be reached directly
or indirectly from the Open_vSwitch table. Except for records in the QoS or Queue tables,
records that are not reachable from the Open_vSwitch table are automatically deleted from
the database. This deletion happens immediately, without waiting for additional ovs-vsctl
commands or other database activity. Thus, a create command must generally be accompanied
by additional commands within the same ovs-vsctl invocation to add a chain of references to
the newly created record from the top-level Open_vSwitch record. The EXAMPLES section
gives some examples that show how to do this.
[--if-exists] destroy table record...
Deletes each specified record from table. Unless --if-exists is specified, each records must
exist.
--all destroy table
Deletes all records from the table.
Caution (ovs-vsctl as example)
The destroy command is only useful for records in the QoS or Queue tables. Records in
other tables are automatically deleted from the database when they become unreachable from
the Open_vSwitch table. This means that deleting the last reference to a record is
sufficient for deleting the record itself. For records in these tables, destroy is
silently ignored. See the EXAMPLES section below for more information.
wait-until table record [column[:key]=value]...
Waits until table contains a record named record whose column equals value or, if key is
specified, whose column contains a key with the specified value. Any of the operators !=, <, >,
<=, or >= may be substituted for = to test for inequality, less than, greater than, less than or
equal to, or greater than or equal to, respectively. (Don't forget to escape < or > from
interpretation by the shell.)
If no column[:key]=value arguments are given, this command waits only until record exists. If
more than one such argument is given, the command waits until all of them are satisfied.
Caution (ovs-vsctl as example)
Usually wait-until should be placed at the beginning of a set of ovs-vsctl commands. For
example, wait-until bridge br0 -- get bridge br0 datapath_id waits until a bridge named br0
is created, then prints its datapath_id column, whereas get bridge br0 datapath_id --
wait-until bridge br0 will abort if no bridge named br0 exists when ovs-vsctl initially
connects to the database.
Consider specifying --timeout=0 along with --wait-until, to prevent ovn-sbctl from terminating
after waiting only at most 5 seconds.
comment [arg]...
This command has no effect on behavior, but any database log record created by the command will
include the command and its arguments.
EXIT STATUS
0 Successful program execution.
1 Usage, syntax, or configuration file error.
SEE ALSO
ovn-sb(5).
Open vSwitch 2.9.8 ovn-sbctl(8)