#include <systemd/sd-login.h>
sd_get_seats()
Similarly, sd_get_sessions() may be used to determine all current login sessions.
Similarly, sd_get_uids() may be used to determine all Unix users who currently have login sessions.
Similarly, sd_get_machine_names() may be used to determine all current virtual machines and containers on the system.
Note that the returned lists are not sorted and in an undefined order.
On success, sd_get_seats(), sd_get_sessions(), sd_get_uids() and sd_get_machine_names() return the number of entries in the arrays. On failure, these calls return a negative errno-style error code.
Returned errors may indicate the following problems:
-ENOMEM
These APIs are implemented as a shared library, which can be compiled and linked to with the libsystemd pkg-config(1) file.
systemd(1), sd-login(3), sd_session_get_seat(3)