Provided by: systemd_255.4-1ubuntu8_amd64 
NAME
varlinkctl - Introspect with and invoke Varlink services
SYNOPSIS
varlinkctl [OPTIONS...] info ADDRESS
varlinkctl [OPTIONS...] list-interfaces ADDRESS
varlinkctl [OPTIONS...] introspect ADDRESS INTERFACE
varlinkctl [OPTIONS...] call ADDRESS METHOD [PARAMETERS]
varlinkctl [OPTIONS...] validate-idl [FILE]
DESCRIPTION
varlinkctl may be used to introspect and invoke Varlink[1] services.
Services are referenced by one of the following:
• A Varlink service reference starting with the "unix:" string, followed by an absolute
AF_UNIX 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.
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. "./").
COMMANDS
The following commands are understood:
info ADDRESS
Show brief information about the specified service, including vendor name and list of
implemented interfaces. Expects a service address in the formats described above.
Added in version 255.
list-interfaces ADDRESS
Show list of interfaces implemented by the specified service. Expects a service
address in the formats described above.
Added in version 255.
introspect ADDRESS INTERFACE
Show interface definition of the specified interface provided by the specified
service. Expects a service address in the formats described above and a Varlink
interface name.
Added in version 255.
call ADDRESS METHOD [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.
Added in version 255.
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.
Added in version 255.
help
Show command syntax help.
Added in version 255.
OPTIONS
The following options are understood:
--more
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.
Added in version 255.
--oneway
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.
Added in version 255.
--json=MODE
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".
Added in version 255.
-j
Equivalent to --json=pretty when invoked interactively from a terminal. Otherwise
equivalent to --json=short, in particular when the output is piped to some other
program.
Added in version 255.
--no-pager
Do not pipe output into a pager.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
EXAMPLES
Example 1. Investigating a Service
The following three commands inspect the "io.systemd.Resolve" service implemented by
systemd-resolved.service(8), 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.)
Example 2. Invoking a Method
The following command resolves a hostname via systemd-resolved.service(8)'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
}
Example 3. Investigating a Service Executable
The 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 ALSO
busctl(1), Varlink[1]
NOTES
1. Varlink
https://varlink.org/