1SD_SESSION_IS_ACTIVE(3) sd_session_is_active SD_SESSION_IS_ACTIVE(3)
2
6 sd_session_is_active, sd_session_is_remote, sd_session_get_state,
7 sd_session_get_uid, sd_session_get_username, sd_session_get_seat,
8 sd_session_get_start_time, sd_session_get_service, sd_session_get_type,
9 sd_session_get_class, sd_session_get_desktop, sd_session_get_display,
10 sd_session_get_tty, sd_session_get_vt, sd_session_get_remote_host,
11 sd_session_get_remote_user, sd_session_get_leader - Determine state of
12 a specific session
13
15 #include <systemd/sd-login.h>
16 int sd_session_is_active(const char *session);
18 int sd_session_is_remote(const char *session);
20 int sd_session_get_state(const char *session, char **state);
22 int sd_session_get_uid(const char *session, uid_t *uid);
24 int sd_session_get_username(const char *session, char **username);
26 int sd_session_get_seat(const char *session, char **seat);
28 int sd_session_get_start_time(const char *session, uint64_t *usec);
30 int sd_session_get_service(const char *session, char **service);
32 int sd_session_get_type(const char *session, char **type);
34 int sd_session_get_class(const char *session, char **class);
36 int sd_session_get_desktop(const char *session, char **desktop);
38 int sd_session_get_display(const char *session, char **display);
40 int sd_session_get_leader(const char *session, pid_t *leader);
42 int sd_session_get_remote_host(const char *session,
44 char **remote_host);
45 int sd_session_get_remote_user(const char *session,
47 char **remote_user);
48 int sd_session_get_tty(const char *session, char **tty);
50 int sd_session_get_vt(const char *session, unsigned int *vt);
52
54 sd_session_is_active() may be used to determine whether the session
55 identified by the specified session identifier is currently active
56 (i.e. currently in the foreground and available for user input) or not.
57 sd_session_is_remote() may be used to determine whether the session
59 identified by the specified session identifier is a remote session
60 (i.e. its remote host is known) or not.
61 sd_session_get_state() may be used to determine the state of the
63 session identified by the specified session identifier. The following
64 states are currently known: "online" (session logged in, but session
65 not active, i.e. not in the foreground), "active" (session logged in
66 and active, i.e. in the foreground), "closing" (session nominally
67 logged out, but some processes belonging to it are still around). In
68 the future additional states might be defined, client code should be
69 written to be robust in regards to additional state strings being
70 returned. This function is a more generic version of
71 sd_session_is_active(). The returned string needs to be freed with the
72 libc free(3) call after use.
73 sd_session_get_uid() may be used to determine the user identifier of
75 the Unix user the session identified by the specified session
76 identifier belongs to.
77 sd_session_get_username() may be used to determine the name of the Unix
79 user the session identified by the specified session identifier belongs
80 to. The returned string needs to be freed with the libc free(3) call
81 after use.
82 sd_session_get_seat() may be used to determine the seat identifier of
84 the seat the session identified by the specified session identifier
85 belongs to. Note that not all sessions are attached to a seat, this
86 call will fail (returning -ENODATA) for them. The returned string needs
87 to be freed with the libc free(3) call after use.
88 sd_session_get_start_time() may be used to determine the start time of
90 the session identified by the specified session identifier belongs to.
91 The usec is in microseconds since the epoch (CLOCK_REALTIME).
92 sd_session_get_service() may be used to determine the name of the
94 service (as passed during PAM session setup) that registered the
95 session identified by the specified session identifier. The returned
96 string needs to be freed with the libc free(3) call after use.
97 sd_session_get_type() may be used to determine the type of the session
99 identified by the specified session identifier. The returned string is
100 one of "x11", "wayland", "tty", "mir" or "unspecified" and needs to be
101 freed with the libc free(3) call after use.
102 sd_session_get_class() may be used to determine the class of the
104 session identified by the specified session identifier. The returned
105 string is one of "user", "greeter", "lock-screen", or "background" and
106 needs to be freed with the libc free(3) call after use.
107 sd_session_get_desktop() may be used to determine the brand of the
109 desktop running on the session identified by the specified session
110 identifier. This field can be set freely by desktop environments and
111 does not follow any special formatting. However, desktops are strongly
112 recommended to use the same identifiers and capitalization as for
113 $XDG_CURRENT_DESKTOP, as defined by the Desktop Entry Specification[1].
114 The returned string needs to be freed with the libc free(3) call after
115 use.
116 sd_session_get_display() may be used to determine the X11 display of
118 the session identified by the specified session identifier. The
119 returned string needs to be freed with the libc free(3) call after use.
120 sd_session_get_leader() may be used to determine the PID of the leader
122 of the session identified by the specified session identifier.
123 sd_session_get_remote_host() may be used to determine the remote
125 hostname of the session identified by the specified session identifier.
126 The returned string needs to be freed with the libc free(3) call after
127 use.
128 sd_session_get_remote_user() may be used to determine the remote
130 username of the session identified by the specified session identifier.
131 The returned string needs to be freed with the libc free(3) call after
132 use. Note that this value is rarely known to the system, and even then
133 should not be relied on.
134 sd_session_get_tty() may be used to determine the TTY device of the
136 session identified by the specified session identifier. The returned
137 string needs to be freed with the libc free(3) call after use.
138 sd_session_get_vt() may be used to determine the VT number of the
140 session identified by the specified session identifier. This function
141 will return an error if the seat does not support VTs.
142 If the session parameter of any of these functions is passed as NULL,
144 the operation is executed for the session the calling process is a
145 member of, if there is any.
146
148 If the test succeeds, sd_session_is_active() and sd_session_is_remote()
149 return a positive integer; if it fails, 0. On success,
150 sd_session_get_state(), sd_session_get_uid(),
151 sd_session_get_username(), sd_session_get_seat(),
152 sd_session_get_service(), sd_session_get_type(),
153 sd_session_get_class(), sd_session_get_display(),
154 sd_session_get_leader(), sd_session_get_remote_user(),
155 sd_session_get_remote_host() and sd_session_get_tty() return 0 or a
156 positive integer. On failure, these calls return a negative errno-style
157 error code.
158 Errors
160 Returned errors may indicate the following problems:
161 -ENXIO
163 The specified session does not exist.
164 -ENODATA
166 The given field is not specified for the described session.
167 -EINVAL
169 An input parameter was invalid (out of range, or NULL, where that
170 is not accepted).
171 -ENOMEM
173 Memory allocation failed.
174
176 Functions described here are available as a shared library, which can
177 be compiled against and linked to with the libsystemd pkg-config(1)
178 file.
179 The code described here uses getenv(3), which is declared to be not
181 multi-thread-safe. This means that the code calling the functions
182 described here must not call setenv(3) from a parallel thread. It is
183 recommended to only do calls to setenv() from an early phase of the
184 program when no other threads have been started.
185
187 systemd(1), sd-login(3), sd_pid_get_session(3)
188
190 1. Desktop Entry Specification
191 https://standards.freedesktop.org/desktop-entry-spec/latest/
192systemd 254 SD_SESSION_IS_ACTIVE(3)