Re: [vincent@vinc17.org: Re: Bug#205685: clone corruption]

[Clint Adams <clint@zsh.org>]

> Hope that explains clone better.

Good now?

Index: Doc/Zsh/mod_clone.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/mod_clone.yo,v
retrieving revision 1.1.1.8
diff -u -r1.1.1.8 mod_clone.yo
--- Doc/Zsh/mod_clone.yo	20 Dec 1999 11:24:39 -0000	1.1.1.8
+++ Doc/Zsh/mod_clone.yo	30 Jul 2004 16:02:38 -0000
@@ -16,5 +16,32 @@
 
 The return value of the builtin is zero in both shells if successful,
 and non-zero on error.
+
+The target of tt(clone) should be an unused terminal, such as an unused virtual
+console or a virtual terminal created by
+
+xterm -e sh -c 'trap : INT QUIT TSTP; tty; while :; do sleep 100000000; done'
+
+Some words of explanation are warranted about this long xterm command
+line: when doing clone on a pseudo-terminal, some other session
+("session" meant as a unix session group, or SID) is already owning
+the terminal. Hence the cloned zsh cannot acquire the pseudo-terminal
+as a controlling tty. That means two things:
+
+      the job control signals will go to the sh-started-by-xterm process
+      group (that's why we disable INT QUIT and TSTP with trap; otherwise
+      the while loop could get suspended or killed)
+
+      the cloned shell will have job control disabled, and the job
+      control keys (control-C, control-\ and control-Z) will not work.
+
+This does not apply when cloning to an bf(unused) vc.
+
+Cloning to an used (and unprepared) terminal will result in two
+processes reading simultaneously from the same terminal, with
+input bytes going randomly to either process.
+
+tt(clone) is mostly useful as a shell built-in replacement for
+openvt.
 )
 enditem()