SD_SESSION_IS_ACTIVE(3) sd_session_is_active SD_SESSION_IS_ACTIVE(3)
NAME
sd_session_is_active, sd_session_is_remote, sd_session_get_state,
sd_session_get_uid, sd_session_get_seat, 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 - Determine
state of a specific session
SYNOPSIS
#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_seat(const char *session, char **seat);
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_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 *vt);
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_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_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", "greeter", "lock-screen", or "background" 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[1].
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_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.
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_seat(),
sd_session_get_service(), sd_session_get_type(),
sd_session_get_class(), sd_session_get_display(),
sd_session_get_remote_user(), sd_session_get_remote_host() and
sd_session_get_tty() 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.
NOTES
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
SEE ALSO
systemd(1), sd-login(3), sd_pid_get_session(3)
NOTES
1. Desktop Entry Specification
https://standards.freedesktop.org/desktop-entry-spec/latest/
systemd 252 SD_SESSION_IS_ACTIVE(3)
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