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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_PID_GET_OWNER_UID(3) sd_pid_get_owner_uid SD_PID_GET_OWNER_UID(3)
sd_pid_get_owner_uid, sd_pid_get_session, sd_pid_get_user_unit,
sd_pid_get_unit, sd_pid_get_machine_name, sd_pid_get_slice,
sd_pid_get_user_slice, sd_pid_get_cgroup, sd_pidfd_get_owner_uid,
sd_pidfd_get_session, sd_pidfd_get_user_unit, sd_pidfd_get_unit,
sd_pidfd_get_machine_name, sd_pidfd_get_slice,
sd_pidfd_get_user_slice, sd_pidfd_get_cgroup,
sd_peer_get_owner_uid, sd_peer_get_session, sd_peer_get_user_unit,
sd_peer_get_unit, sd_peer_get_machine_name, sd_peer_get_slice,
sd_peer_get_user_slice, sd_peer_get_cgroup - Determine the owner
uid of the user unit or session, or the session, user unit, system
unit, container/VM or slice that a specific PID or socket peer
belongs to
#include <systemd/sd-login.h>
int sd_pid_get_owner_uid(pid_t pid, uid_t *uid);
int sd_pid_get_session(pid_t pid, char **session);
int sd_pid_get_user_unit(pid_t pid, char **unit);
int sd_pid_get_unit(pid_t pid, char **unit);
int sd_pid_get_machine_name(pid_t pid, char **name);
int sd_pid_get_slice(pid_t pid, char **slice);
int sd_pid_get_user_slice(pid_t pid, char **slice);
int sd_pid_get_cgroup(pid_t pid, char **cgroup);
int sd_pidfd_get_owner_uid(int pidfd, uid_t *uid);
int sd_pidfd_get_session(int pidfd, char **session);
int sd_pidfd_get_user_unit(int pidfd, char **unit);
int sd_pidfd_get_unit(int pidfd, char **unit);
int sd_pidfd_get_machine_name(int pidfd, char **name);
int sd_pidfd_get_slice(int pidfd, char **slice);
int sd_pidfd_get_user_slice(int pidfd, char **slice);
int sd_pidfd_get_cgroup(int pidfd, char **cgroup);
int sd_peer_get_owner_uid(int fd, uid_t *uid);
int sd_peer_get_session(int fd, char **session);
int sd_peer_get_user_unit(int fd, char **unit);
int sd_peer_get_unit(int fd, char **unit);
int sd_peer_get_machine_name(int fd, char **name);
int sd_peer_get_slice(int fd, char **slice);
int sd_peer_get_user_slice(int fd, char **slice);
int sd_peer_get_cgroup(int fd, char **cgroup);
sd_pid_get_owner_uid() may be used to determine the Unix UID (user
identifier) which owns the login session or systemd user unit of a
process identified by the specified PID. For processes which are
not part of a login session and not managed by a user manager,
this function will fail with -ENODATA.
sd_pid_get_session() may be used to determine the login session
identifier of a process identified by the specified process
identifier. The session identifier is a short string, suitable for
usage in file system paths. Please note the login session may be
limited to a stub process or two. User processes may instead be
started from their systemd user manager, e.g. GUI applications
started using DBus activation, as well as service processes which
are shared between multiple logins of the same user. For processes
which are not part of a login session, this function will fail
with -ENODATA. The returned string needs to be freed with the libc
free(3) call after use.
sd_pid_get_user_unit() may be used to determine the systemd user
unit (i.e. user service or scope unit) identifier of a process
identified by the specified PID. The unit name is a short string,
suitable for usage in file system paths. For processes which are
not managed by a user manager, this function will fail with
-ENODATA. The returned string needs to be freed with the libc
free(3) call after use.
sd_pid_get_unit() may be used to determine the systemd system unit
(i.e. system service or scope unit) identifier of a process
identified by the specified PID. The unit name is a short string,
suitable for usage in file system paths. Note that not all
processes are part of a system unit/service. For processes not
being part of a systemd system unit, this function will fail with
-ENODATA. (More specifically, this call will not work for kernel
threads.) The returned string needs to be freed with the libc
free(3) call after use.
sd_pid_get_machine_name() may be used to determine the name of the
VM or container is a member of. The machine name is a short
string, suitable for usage in file system paths. The returned
string needs to be freed with the libc free(3) call after use. For
processes not part of a VM or container, this function fails with
-ENODATA.
sd_pid_get_slice() may be used to determine the slice unit the
process is a member of. See systemd.slice(5) for details about
slices. The returned string needs to be freed with the libc
free(3) call after use.
Similarly, sd_pid_get_user_slice() returns the user slice (as
managed by the user's systemd instance) of a process.
sd_pid_get_cgroup() returns the control group path of the
specified process, relative to the root of the hierarchy. Returns
the path without trailing slash, except for processes located in
the root control group, where "/" is returned. To find the actual
control group path in the file system, the returned path needs to
be prefixed with /sys/fs/cgroup/.
If the pid parameter of any of these functions is passed as 0, the
operation is executed for the calling process.
The sd_pidfd_get_owner_uid(), sd_pidfd_get_session(),
sd_pidfd_get_user_unit(), sd_pidfd_get_unit(),
sd_pidfd_get_machine_name(), sd_pidfd_get_slice(),
sd_pidfd_get_user_slice() and sd_pidfd_get_cgroup() calls operate
similarly to their PID counterparts, but accept a PIDFD instead of
a PID, which means they are not subject to recycle race conditions
as the process is pinned by the file descriptor during the whole
duration of the invocation. Note that these require a kernel that
supports PIDFD. A suitable file descriptor may be acquired via
pidfd_open(2).
The sd_peer_get_owner_uid(), sd_peer_get_session(),
sd_peer_get_user_unit(), sd_peer_get_unit(),
sd_peer_get_machine_name(), sd_peer_get_slice(),
sd_peer_get_user_slice() and sd_peer_get_cgroup() calls operate
similarly to their PID counterparts, but accept a connected
AF_UNIX socket and retrieve information about the connected peer
process. Note that these fields are retrieved via /proc/, and
hence are not suitable for authorization purposes, as they are
subject to races.
On success, these calls 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:
-ESRCH
The specified PID does not refer to a running process.
-EBADF
The specified file descriptor is invalid.
-ENODATA
The given field is not specified for the described process or
peer.
-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.
Note that the login session identifier as returned by
sd_pid_get_session() is completely unrelated to the process
session identifier as returned by getsid(2).
sd_peer_get_cgroup(), sd_peer_get_machine_name(),
sd_peer_get_owner_uid(), sd_peer_get_session(),
sd_peer_get_slice(), sd_peer_get_unit(), sd_peer_get_user_slice(),
sd_peer_get_user_unit(), sd_pid_get_cgroup(),
sd_pid_get_machine_name(), sd_pid_get_owner_uid(),
sd_pid_get_session(), sd_pid_get_slice(), sd_pid_get_unit(),
sd_pid_get_user_slice(), and sd_pid_get_user_unit() were added in
version 236.
sd_pidfd_get_owner_uid(), sd_pidfd_get_session(),
sd_pidfd_get_user_unit(), sd_pidfd_get_unit(),
sd_pidfd_get_machine_name(), sd_pidfd_get_slice(),
sd_pidfd_get_user_slice(), and sd_pidfd_get_cgroup() were added in
version 253.
systemd(1), sd-login(3), sd_session_is_active(3), getsid(2),
systemd.slice(5), systemd-machined.service(8)
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_PID_GET_OWNER_UID(3)
Pages that refer to this page: homectl(1), importctl(1), journalctl(1), localectl(1), loginctl(1), machinectl(1), portablectl(1), systemctl(1), systemd(1), systemd-analyze(1), systemd-inhibit(1), systemd-nspawn(1), systemd-vmspawn(1), timedatectl(1), updatectl(1), userdbctl(1), sd-login(3), sd_machine_get_class(3), sd_session_is_active(3), sd_uid_get_state(3), systemd.directives(7), systemd.index(7), systemd-tmpfiles(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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