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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |NOTES |HISTORY |SEE ALSO |NOTES |COLOPHON | |
SD_SESSION_IS_ACTIVE(3) sd_session_is_activeSD_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 ofsd_session_is_active(). The returned string needs to be freed with the libcfree(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 libcfree(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 libcfree(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. Theusec 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 libcfree(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 libcfree(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 libcfree(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 theDesktop Entry Specification[1]. The returned string needs to be freed with the libcfree(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 libcfree(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 libcfree(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 libcfree(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 libcfree(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 thesession parameter of any of these functions is passed asNULL, 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()andsd_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()andsd_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, orNULL, 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 thelibsystemd pkg-config(1) file. The code described here usesgetenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not callsetenv(3) from a parallel thread. It is recommended to only do calls tosetenv()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(), andsd_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(), andsd_session_get_leader()were added in version 254.
systemd(1),sd-login(3),sd_pid_get_session(3)
1. Desktop Entry Specificationhttps://standards.freedesktop.org/desktop-entry-spec/latest/
This page is part of thesystemd (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 isnot part of the original manual page), send a mail to man-pages@man7.orgsystemd 258~rc2SD_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)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |