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NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | EXAMPLES | SEE ALSO | NOTES | COLOPHON |
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VARLINKCTL(1) varlinkctl VARLINKCTL(1)
varlinkctl - Introspect with and invoke Varlink services
varlinkctl [OPTIONS...] info ADDRESS
varlinkctl [OPTIONS...] list-interfaces ADDRESS
varlinkctl [OPTIONS...] introspect ADDRESS [INTERFACE]
varlinkctl [OPTIONS...] call ADDRESS METHOD [ARGUMENTS]
varlinkctl [OPTIONS...] validate-idl [FILE]
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 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. "./").
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 one of 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 one of the formats described
above.
Added in version 255.
list-methods ADDRESS [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.
Added in version 257.
introspect ADDRESS [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.
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.
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.
--collect
This is similar to --more but collects all responses in a
JSON array, and prints it, rather than in JSON_SEQ mode.
Added in version 256.
--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.
--quiet, -q
Suppress output of method call replies.
Added in version 257.
--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.
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"}'
{}
busctl(1), Varlink[1]
1. Varlink
https://varlink.org/
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 257~devel VARLINKCTL(1)
Pages that refer to this page: busctl(1), systemd.directives(7), systemd.index(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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