PR_SET_CHILD_SUBREAPER(2const) PR_SET_CHILD_SUBREAPER(2const)
NAME
PR_SET_CHILD_SUBREAPER - set/unset the "child subreaper" attribute of
the calling process
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <linux/prctl.h> /* Definition of PR_* constants */
#include <sys/prctl.h>
int prctl(PR_SET_CHILD_SUBREAPER, long set);
DESCRIPTION
If set is nonzero, set the "child subreaper" attribute of the calling
process; if set is zero, unset the attribute.
A subreaper fulfills the role of init(1) for its descendant processes.
When a process becomes orphaned (i.e., its immediate parent terminates),
then that process will be reparented to the nearest still living ances-
tor subreaper. Subsequently, calls to getppid(2) in the orphaned
process will now return the PID of the subreaper process, and when the
orphan terminates, it is the subreaper process that will receive a
SIGCHLD signal and will be able to wait(2) on the process to discover
its termination status.
The setting of the "child subreaper" attribute is not inherited by chil-
dren created by fork(2) and clone(2). The setting is preserved across
execve(2).
Establishing a subreaper process is useful in session management frame-
works where a hierarchical group of processes is managed by a subreaper
process that needs to be informed when one of the processes—for example,
a double-forked daemon—terminates (perhaps so that it can restart that
process). Some init(1) frameworks (e.g., systemd(1)) employ a subreaper
process for similar reasons.
RETURN VALUE
On success, 0 is returned. On error, -1 is returned, and errno is set
to indicate the error.
STANDARDS
Linux.
HISTORY
Linux 3.4.
SEE ALSO
prctl(2), PR_GET_CHILD_SUBREAPER(2const)
Linux man-pages 6.9.1 2024-06-02 PR_SET_CHILD_SUBREAPER(2const)
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