'\" t
.TH "SD_PID_GET_SESSION" "3" "" "systemd 215" "sd_pid_get_session"
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.SH "NAME"
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_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 \- Determine session, service, owner of a session, container/VM or slice of a specific PID or socket peer
.SH "SYNOPSIS"
.sp
.ft B
.nf
#include <systemd/sd\-login\&.h>
.fi
.ft
.HP \w'int\ sd_pid_get_session('u
.BI "int sd_pid_get_session(pid_t\ " "pid" ", char\ **" "session" ");"
.HP \w'int\ sd_pid_get_unit('u
.BI "int sd_pid_get_unit(pid_t\ " "pid" ", char\ **" "unit" ");"
.HP \w'int\ sd_pid_get_user_unit('u
.BI "int sd_pid_get_user_unit(pid_t\ " "pid" ", char\ **" "unit" ");"
.HP \w'int\ sd_pid_get_owner_uid('u
.BI "int sd_pid_get_owner_uid(pid_t\ " "pid" ", uid_t\ *" "uid" ");"
.HP \w'int\ sd_pid_get_machine_name('u
.BI "int sd_pid_get_machine_name(pid_t\ " "pid" ", char\ **" "name" ");"
.HP \w'int\ sd_pid_get_slice('u
.BI "int sd_pid_get_slice(pid_t\ " "pid" ", char\ **" "slice" ");"
.HP \w'int\ sd_peer_get_session('u
.BI "int sd_peer_get_session(int\ " "fd" ", char\ **" "session" ");"
.HP \w'int\ sd_peer_get_unit('u
.BI "int sd_peer_get_unit(int\ " "fd" ", char\ **" "unit" ");"
.HP \w'int\ sd_peer_get_user_unit('u
.BI "int sd_peer_get_user_unit(int\ " "fd" ", char\ **" "unit" ");"
.HP \w'int\ sd_peer_get_owner_uid('u
.BI "int sd_peer_get_owner_uid(int\ " "fd" ", uid_t\ *" "uid" ");"
.HP \w'int\ sd_peer_get_machine_name('u
.BI "int sd_peer_get_machine_name(int\ " "fd" ", char\ **" "name" ");"
.HP \w'int\ sd_peer_get_slice('u
.BI "int sd_peer_get_slice(int\ " "fd" ", char\ **" "slice" ");"
.SH "DESCRIPTION"
.PP
\fBsd_pid_get_session()\fR
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\&. The returned string needs to be freed with the libc
\fBfree\fR(3)
call after use\&.
.PP
\fBsd_pid_get_unit()\fR
may be used to determine the systemd system unit (i\&.e\&. system service) 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\&. (More specifically: this call will not work for processes that are part of user units, use
\fBsd_pid_get_user_unit()\fR
for that\&.) The returned string needs to be freed with the libc
\fBfree\fR(3)
call after use\&.
.PP
\fBsd_pid_get_user_unit()\fR
may be used to determine the systemd user unit (i\&.e\&. user service) identifier of a process identified by the specified PID\&. This is similar to
\fBsd_pid_get_unit()\fR
but applies to user units instead of system units\&.
.PP
\fBsd_pid_get_owner_uid()\fR
may be used to determine the Unix 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, where
\fBsd_pid_get_session()\fR
will fail\&. For processes not being part of a login session and not being a shared process of a user this function will fail\&.
.PP
\fBsd_pid_get_machine_name()\fR
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
\fBfree\fR(3)
call after use\&.
.PP
\fBsd_pid_get_slice()\fR
may be used to determine the slice unit the process is a member of\&. See
\fBsystemd.slice\fR(5)
for details about slices\&. The returned string needs to be freed with the libc
\fBfree\fR(3)
call after use\&.
.PP
If the
\fIpid\fR
parameter of any of these functions is passed as 0, the operation is executed for the calling process\&.
.PP
The
\fBsd_peer_get_session()\fR,
\fBsd_peer_get_unit()\fR,
\fBsd_peer_get_user_unit()\fR,
\fBsd_peer_get_owner_uid()\fR,
\fBsd_peer_get_machine_name()\fR
and
\fBsd_peer_get_slice()\fR
calls operate similar to their PID counterparts, but operate on a connected AF_UNIX socket and retrieve information about the connected peer process\&.
.SH "RETURN VALUE"
.PP
On success, these calls return 0 or a positive integer\&. On failure, these calls return a negative errno\-style error code\&.
.SH "NOTES"
.PP
The
\fBsd_pid_get_session()\fR,
\fBsd_pid_get_unit()\fR,
\fBsd_pid_get_user_unit()\fR,
\fBsd_pid_get_owner_uid()\fR,
\fBsd_pid_get_machine_name()\fR,
\fBsd_pid_get_slice()\fR,
\fBsd_peer_get_session()\fR,
\fBsd_peer_get_unit()\fR,
\fBsd_peer_get_user_unit()\fR,
\fBsd_peer_get_owner_uid()\fR,
\fBsd_peer_get_machine_name()\fR
and
\fBsd_peer_get_slice()\fR
interfaces are available as a shared library, which can be compiled and linked to with the
\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
file\&.
.PP
Note that the login session identifier as returned by
\fBsd_pid_get_session()\fR
is completely unrelated to the process session identifier as returned by
\fBgetsid\fR(2)\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsd-login\fR(3),
\fBsd_session_is_active\fR(3),
\fBgetsid\fR(2),
\fBsystemd.slice\fR(5)