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 ancestor 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
       children created by fork(2) and clone(2).  The setting is preserved
       across execve(2).

       Establishing a subreaper process is useful in session management
       frameworks 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)