exec last command in last pipeline.

exec last command in last pipeline.

[Tanaka Akira]

Z:akr@is27e1u11% zsh -frc 'exec echo a'
a
Z:akr@is27e1u11% zsh -fc 'exec > /dev/null'
zsh: redirection with no command
zsh: exit 1     zsh -fc 'exec > /dev/null'
Z:akr@is27e1u11% zsh -fc 'exec printenv SHLVL'
2
Z:akr@is27e1u11% zsh -c 'print $$; sh -c '\''echo $$; printenv SHLVL'\'''
9076
9076
2
Z:akr@is27e1u11% 

I think they should be:

Z:akr@is27e1u11% zsh -frc 'exec echo a'        
exec: echo: restricted
zsh: exit 1     zsh -frc 'exec echo a'
Z:akr@is27e1u11% zsh -fc 'exec > /dev/null' 
Z:akr@is27e1u11% zsh -fc 'exec printenv SHLVL' 
1
Z:akr@is27e1u11% zsh -c 'print $$; sh -c '\''echo $$; printenv SHLVL'\''' 
9078
9078
1
Z:akr@is27e1u11% 

Index: exec.c
===================================================================
RCS file: /projects/zsh/zsh/Src/exec.c,v
retrieving revision 1.1.1.19
diff -u -F^( -r1.1.1.19 exec.c
--- exec.c	1999/07/24 14:02:56	1.1.1.19
+++ exec.c	1999/08/14 15:55:32
@@ -1522,7 +1522,7 @@
 
 	    /* Current shell should not fork unless the *
 	     * exec occurs at the end of a pipeline.    */
-	    if ((cflags & BINF_EXEC) && last1 == 2)
+	    if ((cflags & BINF_EXEC) && last1)
 		flags |= CFLAG_EXEC;
 
 	    /* Empty command */
@@ -2053,8 +2053,9 @@
 	    restore_params(restorelist, removelist);
 
 	} else {
-	    if (flags & CFLAG_EXEC) {
+	    if (!forked)
 		setiparam("SHLVL", --shlvl);
+	    if (flags & CFLAG_EXEC) {
 		/* If we are exec'ing a command, and we are not *
 		 * in a subshell, then save the history file.   */
 		if (!subsh && isset(RCS) && interact && !nohistsave)
-- 
Tanaka Akira

Re: exec last command in last pipeline.

[Bart Schaefer]

On Aug 15,  1:04am, Tanaka Akira wrote:
} Subject: exec last command in last pipeline.
}
} --- exec.c	1999/07/24 14:02:56	1.1.1.19
} +++ exec.c	1999/08/14 15:55:32
} @@ -1522,7 +1522,7 @@
}  
}  	    /* Current shell should not fork unless the *
}  	     * exec occurs at the end of a pipeline.    */
} -	    if ((cflags & BINF_EXEC) && last1 == 2)
} +	    if ((cflags & BINF_EXEC) && last1)
}  		flags |= CFLAG_EXEC;
}  
}  	    /* Empty command */

I'm extremely dubious of that change.  The only way that last1 can be set
to 2 is here in execpline2():

    if (pline->type == END)
    	execcmd(pline->left, input, output, how, last1 ? 1 : 2);

If you remove the test of last1 == 2 in execcmd(), there's no reason to
test for last1 in execpline2().  But both tests have been there since
before version 3.0.0; I'm concerned that the shell is going to exec in
some cases where it should not.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Re: exec last command in last pipeline.

[Tanaka Akira]

In article <990814220530.ZM6932@candle.brasslantern.com>,
  "Bart Schaefer" <schaefer@candle.brasslantern.com> writes:

> If you remove the test of last1 == 2 in execcmd(), there's no reason to
> test for last1 in execpline2().  But both tests have been there since
> before version 3.0.0; I'm concerned that the shell is going to exec in
> some cases where it should not.

    if ((how & Z_ASYNC) || (!(flags & CFLAG_EXEC) &&
       (((is_builtin || is_shfunc) && output) ||
       (!is_cursh && (last1 != 1 || sigtrapped[SIGZERR] ||
        sigtrapped[SIGEXIT] || havefiles()))))) {

and
            if (last1 == 1)

(and
                DPUTS(last1 != 1 && !forked, "BUG: not exiting?");
)

can be the reason to set last1 to 2 instead of 1.
-- 
Tanaka Akira