Module Name: src
Committed By: riastradh
Date: Sat Jul 15 13:49:26 UTC 2023
Modified Files:
src/share/man/man7: signal.7
Log Message:
signal(7): Clarify quirky SysV-inspired SIGCHLD semantics.
Suggest a portable alternative approach for detaching subprocesses.
Break wall of text into paragraphs while here.
To generate a diff of this commit:
cvs rdiff -u -r1.26 -r1.27 src/share/man/man7/signal.7
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/share/man/man7/signal.7
diff -u src/share/man/man7/signal.7:1.26 src/share/man/man7/signal.7:1.27
--- src/share/man/man7/signal.7:1.26 Sun May 30 07:17:01 2021
+++ src/share/man/man7/signal.7 Sat Jul 15 13:49:26 2023
@@ -1,4 +1,4 @@
-.\" $NetBSD: signal.7,v 1.26 2021/05/30 07:17:01 dholland Exp $
+.\" $NetBSD: signal.7,v 1.27 2023/07/15 13:49:26 riastradh Exp $
.\"
.\" Copyright (c) 1999, 2016 The NetBSD Foundation, Inc.
.\" All rights reserved.
@@ -401,18 +401,24 @@ immediate children exits and can be wait
.Xr wait 2
family of functions.
The default action is to do nothing.
+.Pp
As a special case hack, if
.Dv SIGCHLD
is ignored (not merely blocked) when a process is
.Em created ,
-it is detached from its parent immediately so it need not be waited
-for.
+it is detached from its parent immediately so it need not
+.Pq and cannot
+be waited for.
This behavior is a System V historic wart, implemented in
.Nx
only for compatibility.
It is not portable, not recommended, and should not be used by new
code.
-.\" XXX should refer to something that can be used by new code...
+New code should use the portable technique of forking a child to fork
+or spawn a grandchild, and letting the child exit immediately
+afterward.
+The grandchild process will then be detached.
+.Pp
The number for
.Dv SIGCHLD
is\~20.
