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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | NOTES | COLOPHON |
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SD_SESSION_IS_ACTIVE(3) sd_session_is_active SD_SESSION_IS_ACTIVE(3)
sd_session_is_active, 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 - 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 *vt);
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[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_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.
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.
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() 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.
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_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.
systemd(1), sd-login(3), sd_pid_get_session(3)
1. Desktop Entry Specification
https://standards.freedesktop.org/desktop-entry-spec/latest/
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 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) 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
man-pages@man7.org
systemd 258~rc2 SD_SESSION_IS_ACTIVE(3)
Pages that refer to this page: sd_get_seats(3), sd-login(3), sd_pid_get_owner_uid(3), sd_seat_get_active(3), org.freedesktop.login1(5), systemd.directives(7), systemd.index(7), pam_systemd(8)
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HTML rendering created 2025-09-06 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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