varlinkctlsystemdvarlinkctl1varlinkctlIntrospect with and invoke Varlink servicesvarlinkctlOPTIONSinfoADDRESSvarlinkctlOPTIONSlist-interfacesADDRESSvarlinkctlOPTIONSintrospectADDRESSINTERFACEvarlinkctlOPTIONScallADDRESSMETHODARGUMENTSvarlinkctlOPTIONSvalidate-idlFILEDescriptionvarlinkctl may be used to introspect and invoke Varlink services.Services are referenced by one of the following:A Varlink service reference starting with the unix: string, followed
by an absolute AF_UNIX socket path, or by @ and an arbitrary string
(the latter for referencing sockets in the abstract namespace).A Varlink service reference starting with the exec: string, followed
by an absolute path of a binary to execute.A Varlink service reference starting with the ssh: string, followed
by an SSH host specification, followed by :, followed by an absolute
AF_UNIX socket path. (This requires OpenSSH 9.4 or newer on the server side,
abstract namespace sockets are not supported.)For convenience these two simpler (redundant) service address syntaxes are also supported:A file system path to an AF_UNIX socket, either absolute
(i.e. begins with /) or relative (in which case it must begin with
./).A file system path to an executable, either absolute or relative (as above, must begin
with /, resp. ./).CommandsThe following commands are understood:infoADDRESSShow brief information about the specified service, including vendor name and list of
implemented interfaces. Expects a service address in one of the formats described above.list-interfacesADDRESSShow list of interfaces implemented by the specified service. Expects a service
address in one of the formats described above.list-methodsADDRESS [INTERFACE…]Show list of methods implemented by the specified service. Expects a service address
in one of the formats described above as well as one or more interface names. If no interface name is
specified, lists all methods of all interfaces implemented by the service, otherwise just the methods
in the specified services.introspectADDRESS [INTERFACE…]Show the interface definitions of the specified interfaces provided by the specified
service. Expects a service address in one of the formats described above and optionally one or more
Varlink interface names. If no interface names are specified, shows all provided interfaces by the
service.callADDRESSMETHOD [ARGUMENTS]Call the specified method of the specified service. Expects a service address in the
format described above, a fully qualified Varlink method name, and a JSON arguments object. If the
arguments object is not specified, it is read from STDIN instead. To pass an empty list of
parameters, specify the empty object {}.The reply parameters are written as JSON object to STDOUT.validate-idl [FILE]Reads a Varlink interface definition file, parses and validates it, then outputs it
with syntax highlighting. This checks for syntax and internal consistency of the interface. Expects a
file name to read the interface definition from. If omitted reads the interface definition from
STDIN.helpShow command syntax help.OptionsThe following options are understood:When used with call: expect multiple method replies. If this flag is
set the method call is sent with the more flag set, which tells the service to
generate multiple replies, if needed. The command remains running until the service sends a reply
message that indicates it is the last in the series. This flag should be set only for method calls
that support this mechanism.If this mode is enabled output is automatically switched to JSON-SEQ mode, so that individual
reply objects can be easily discerned.This is similar to but collects all responses in a JSON
array, and prints it, rather than in JSON_SEQ mode.When used with call: do not expect a method reply. If this flag
is set the method call is sent with the oneway flag set (the command exits
immediately after), which tells the service not to generate a reply.Selects the JSON output formatting, one of pretty (for nicely indented,
colorized output) or short (for terse output with minimal whitespace and no
newlines), defaults to short.Equivalent to when invoked interactively from a terminal. Otherwise
equivalent to , in particular when the output is piped to some other
program.Suppress output of method call replies.ExamplesInvestigating a ServiceThe following three commands inspect the io.systemd.Resolve service
implemented by
systemd-resolved.service8,
listing general service information and implemented interfaces, and then displaying the interface
definition of its primary interface:$ varlinkctl info /run/systemd/resolve/io.systemd.Resolve
Vendor: The systemd Project
Product: systemd (systemd-resolved)
Version: 254 (254-1522-g4790521^)
URL: https://systemd.io/
Interfaces: io.systemd
io.systemd.Resolve
org.varlink.service
$ varlinkctl list-interfaces /run/systemd/resolve/io.systemd.Resolve
io.systemd
io.systemd.Resolve
org.varlink.service
$ varlinkctl introspect /run/systemd/resolve/io.systemd.Resolve io.systemd.Resolve
interface io.systemd.Resolve
type ResolvedAddress(
ifindex: ?int,
…(Interface definition has been truncated in the example above, in the interest of brevity.)Invoking a MethodThe following command resolves a hostname via systemd-resolved.service8's ResolveHostname method call.$ varlinkctl call /run/systemd/resolve/io.systemd.Resolve io.systemd.Resolve.ResolveHostname '{"name":"systemd.io","family":2}' -j
{
"addresses" : [
{
"ifindex" : 2,
"family" : 2,
"address" : [
185,
199,
111,
153
]
}
],
"name" : "systemd.io",
"flags" : 1048577
}Investigating a Service ExecutableThe following command inspects the /usr/lib/systemd/systemd-pcrextend
executable and the IPC APIs it provides. It then invokes a method on it:# varlinkctl info /usr/lib/systemd/systemd-pcrextend
Vendor: The systemd Project
Product: systemd (systemd-pcrextend)
Version: 254 (254-1536-g97734fb)
URL: https://systemd.io/
Interfaces: io.systemd
io.systemd.PCRExtend
org.varlink.service
# varlinkctl introspect /usr/lib/systemd/systemd-pcrextend io.systemd.PCRExtend
interface io.systemd.PCRExtend
method Extend(
pcr: int,
text: ?string,
data: ?string
) -> ()
# varlinkctl call /usr/lib/systemd/systemd-pcrextend io.systemd.PCRExtend.Extend '{"pcr":15,"text":"foobar"}'
{}See Alsobusctl1Varlink