sd_pid_get_session, sd_pid_get_unit, sd_pid_get_user_unit,
sd_pid_get_owner_uid, sd_pid_get_machine_name, sd_pid_get_slice,
sd_pid_get_user_slice, sd_pid_get_cgroup, sd_peer_get_session,
sd_peer_get_unit, sd_peer_get_user_unit, sd_peer_get_owner_uid,
sd_peer_get_machine_name, sd_peer_get_slice, sd_peer_get_user_slice,
sd_peer_get_cgroup - Determine session, unit, owner of a session,
container/VM or slice of a specific PID or socket peer
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. Note that not all processes are part of a
login session (e.g. system service processes, user processes that are
shared between multiple sessions of the same user, or kernel
threads). For processes not being 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_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 (e.g. user processes, or kernel
threads). 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_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. This is similar to sd_pid_get_unit(), but
applies to user units instead of system units.
sd_pid_get_owner_uid() may be used to determine the Unix UID (user
identifier) of the owner of the session of a process identified the
specified PID. Note that this function will succeed for user
processes which are shared between multiple login sessions of the
same user, whereas sd_pid_get_session() will fail. For processes not
being part of a login session and not being a shared process of a
user, this function will fail with -ENODATA.
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 containers, 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 unified control group setup is used), or
/sys/fs/cgroup/HIERARCHY/ (if the legacy multi-hierarchy control
group setup is used).
If the pid parameter of any of these functions is passed as 0, the
operation is executed for the calling process.
The sd_peer_get_session(), sd_peer_get_unit(),
sd_peer_get_user_slice() and sd_peer_get_cgroup() calls operate
similar to their PID counterparts, but operate on 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.
Returned errors may indicate the following problems:
The specified PID does not refer to a running process.
The specified socket file descriptor was invalid.
The given field is not specified for the described process or
An input parameter was invalid (out of range, or NULL, where that
is not accepted).
Memory allocation failed.
The sd_pid_get_session(), sd_pid_get_unit(), sd_pid_get_user_unit(),
sd_pid_get_slice(), sd_pid_get_user_slice(), sd_peer_get_session(),
sd_peer_get_unit(), sd_peer_get_user_unit(), sd_peer_get_owner_uid(),
sd_peer_get_machine_name(), sd_peer_get_slice() and
sd_peer_get_user_slice() interfaces are available as a shared
library, which can be compiled 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).
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
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2017-03-13. If you dis‐
cover 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
systemd 233 SD_PID_GET_SESSION(3)