sd_session_is_active

systemd

sd_session_is_remote

sd_session_get_state

sd_session_get_uid

sd_session_get_username

sd_session_get_seat

sd_session_get_start_time

sd_session_get_service

sd_session_get_type

sd_session_get_class

sd_session_get_desktop

sd_session_get_display

sd_session_get_tty

sd_session_get_vt

sd_session_get_remote_host

sd_session_get_remote_user

sd_session_get_leader

sd_session_get_extra_device_access

Determine state of a specific session

#include <systemd/sd-login.h>

int

sd_session_is_active

const char *

session

int

sd_session_is_remote

const char *

session

int

sd_session_get_state

const char *

session

char **

state

int

sd_session_get_uid

const char *

session

uid_t *

uid

int

sd_session_get_username

const char *

session

char **

username

int

sd_session_get_seat

const char *

session

char **

seat

int

sd_session_get_start_time

const char *

session

uint64_t *

usec

int

sd_session_get_service

const char *

session

char **

service

int

sd_session_get_type

const char *

session

char **

type

int

sd_session_get_class

const char *

session

char **

class

int

sd_session_get_desktop

const char *

session

char **

desktop

int

sd_session_get_display

const char *

session

char **

display

int

sd_session_get_leader

const char *

session

pid_t *

leader

int

sd_session_get_remote_host

const char *

session

char **

remote_host

int

sd_session_get_remote_user

const char *

session

char **

remote_user

int

sd_session_get_tty

const char *

session

char **

tty

int

sd_session_get_vt

const char *

session

unsigned int *

int

sd_session_get_extra_device_access

const char *

session

char ***

ret_ids

Description

sd_session_is_active() may be used to determine whether the session identified by the specified session identifier is currently active (i.e. currently in the foreground and available for user input) or not.

sd_session_is_remote() may be used to determine whether the session identified by the specified session identifier is a remote session (i.e. its remote host is known) or not.

sd_session_get_state() may be used to determine the state of the session identified by the specified session identifier. The following states are currently known: online (session logged in, but session not active, i.e. not in the foreground), active (session logged in and active, i.e. in the foreground), closing (session nominally logged out, but some processes belonging to it are still around). In the future additional states might be defined, client code should be written to be robust in regards to additional state strings being returned. This function is a more generic version of sd_session_is_active(). The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_uid() may be used to determine the user identifier of the Unix user the session identified by the specified session identifier belongs to.

sd_session_get_username() may be used to determine the name of the Unix user the session identified by the specified session identifier belongs to. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_seat() may be used to determine the seat identifier of the seat the session identified by the specified session identifier belongs to. Note that not all sessions are attached to a seat, this call will fail (returning -ENODATA) for them. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_start_time() may be used to determine the start time of the session identified by the specified session identifier belongs to. The usec is in microseconds since the epoch (CLOCK_REALTIME).

sd_session_get_service() may be used to determine the name of the service (as passed during PAM session setup) that registered the session identified by the specified session identifier. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_type() may be used to determine the type of the session identified by the specified session identifier. The returned string is one of x11, wayland, tty, mir or unspecified and needs to be freed with the libc free(3) call after use.

sd_session_get_class() may be used to determine the class of the session identified by the specified session identifier. The returned string is one of user, user-early, user-light, user-early-light, user-incomplete, greeter, lock-screen, background, background-light, manager or manager-early and needs to be freed with the libc free(3) call after use.

sd_session_get_desktop() may be used to determine the brand of the desktop running on the session identified by the specified session identifier. This field can be set freely by desktop environments and does not follow any special formatting. However, desktops are strongly recommended to use the same identifiers and capitalization as for $XDG_CURRENT_DESKTOP, as defined by the Desktop Entry Specification. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_display() may be used to determine the X11 display of the session identified by the specified session identifier. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_leader() may be used to determine the PID of the leader of the session identified by the specified session identifier.

sd_session_get_remote_host() may be used to determine the remote hostname of the session identified by the specified session identifier. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_remote_user() may be used to determine the remote username of the session identified by the specified session identifier. The returned string needs to be freed with the libc free(3) call after use. Note that this value is rarely known to the system, and even then should not be relied on.

sd_session_get_tty() may be used to determine the TTY device of the session identified by the specified session identifier. The returned string needs to be freed with the libc free(3) call after use.

sd_session_get_vt() may be used to determine the VT number of the session identified by the specified session identifier. This function will return an error if the seat does not support VTs.

sd_session_get_extra_device_access() may be used to determine which additional hardware devices the session is granted access to. For every ID in the list, the session is granted access to all devices tagged with xaccess-ID in udev.

If the session parameter of any of these functions is passed as NULL, the operation is executed for the session the calling process is a member of, if there is any.

Return Value

If the test succeeds, sd_session_is_active() and sd_session_is_remote() return a positive integer; if it fails, 0. On success, sd_session_get_state(), sd_session_get_uid(), sd_session_get_username(), sd_session_get_seat(), sd_session_get_service(), sd_session_get_type(), sd_session_get_class(), sd_session_get_display(), sd_session_get_leader(), sd_session_get_remote_user(), sd_session_get_remote_host(), sd_session_get_tty(), and sd_session_get_extra_device_access() return 0 or a positive integer. On failure, these calls return a negative errno-style error code.

Errors

Returned errors may indicate the following problems:

-ENXIO
The specified session does not exist.

-ENODATA
The given field is not specified for the described session.

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

-ENOMEM
Memory allocation failed.

History

sd_session_get_state() was added in version 186.

sd_session_get_tty() was added in version 198.

sd_session_get_vt() was added in version 207.

sd_session_is_remote(), sd_session_get_remote_host(), and sd_session_get_remote_user() were added in version 209.

sd_session_get_desktop() was added in version 217.

sd_session_get_username(), sd_session_get_start_time(), and sd_session_get_leader() were added in version 254.

sd_session_get_extra_device_access() was added in version 260.