Index · Directives systemd 256


sd_machine_get_class, sd_machine_get_ifindices — Determine the class and network interface indices of a locally running virtual machine or container


#include <systemd/sd-login.h>
int sd_machine_get_class(const char* machine,
 char **class);
int sd_machine_get_ifindices(const char* machine,
 int **ret_ifindices);


sd_machine_get_class() may be used to determine the class of a locally running virtual machine or container that is registered with systemd-machined.service(8). The string returned is either "vm" or "container". The returned string needs to be freed with the libc free(3) call after use.

sd_machine_get_ifindices() may be used to determine the numeric indices of the network interfaces on the host that are pointing towards the specified locally running virtual machine or container. The vm or container must be registered with systemd-machined.service(8). The output parameter ret_ifindices may be passed as NULL when the output value is not needed. The returned array needs to be freed with the libc free(3) call after use.

Return Value

On success, these functions return a non-negative integer. sd_machine_get_ifindices() returns the number of the relevant network interfaces. On failure, these calls return a negative errno-style error code.


Returned errors may indicate the following problems:


The specified machine does not exist or is currently not running.


An input parameter was invalid (out of range, or NULL, where that is not accepted).


Memory allocation failed.


Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd pkg-config(1) file.

The code described here uses getenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call setenv(3) from a parallel thread. It is recommended to only do calls to setenv() from an early phase of the program when no other threads have been started.


sd_machine_get_class() and sd_machine_get_ifindices() were added in version 217.

See Also

systemd(1), sd-login(3), systemd-machined.service(8), sd_pid_get_machine_name(3)