RE: Parallel Cons Issue

[Jeff Rosenfeld]

It's valid, but not efficient. Parens cause the shell to execute the
enclosed command in a subshell. Mostly handy for obscure sorts of
redirections like:
        (Command 2>&1 >/dev/null) | FilterErrors
or, for csh users:
        (Command >/dev/null) |& FilterErrors

        - Jeff.

-----Original Message-----
From: Rajesh Vaidheeswarran [mailto:address@hidden 
Sent: Thursday, September 06, 2001 4:48 PM
To: Wayne Scott
Cc: address@hidden; address@hidden;
address@hidden
Subject: Re: Parallel Cons Issue


You may not need to test for max_jobs at all, since ( cmd ) is valid
even for a single command.
 
So, that could become

my @cmds = join " && ", map "( $_ )", $self->getcoms($env, $tgt); #
pcons

the simple test being..
% perl -e '@cmds = qw(a b c d e); print join " && ", map "( $_ )",
@cmds'
( a ) && ( b ) && ( c ) && ( d ) && ( e )

% perl -e '@cmds = qw(e); print join " && ", map "( $_ )", @cmds'
( e )


In a previous message, Wayne Scott writes:

> From: "Nolish, Kevin" <address@hidden>
> >     my @cmds = $self->getcoms($env, $tgt); # pcons
> >     if ($param::max_jobs>1) {                  # pcons
> >     for( $i = 0; $i < @cmds; $i++ ) {              #pcons -kn
> >         $cmds[$i] = "( " . $cmds[$i] . " )";       #pcons -kn
> >     }                                              #pcons -kn
> >     @cmds = join(" && ", @cmds) ;      # pcons
> >     }   
> 
> 
> This is cleaner.... but untested.
> 
>     my @cmds = $self->getcoms($env, $tgt); # pcons
>     if ($param::max_jobs>1) {            # pcons
>       @cmds = (join(" && ", map {"( $_ )"} @cmds)) ;      # pcons
>     }   
> 
> -Wayne
> 
> _______________________________________________
> address@hidden
> http://mail.gnu.org/mailman/listinfo/cons-discuss
> Cons URL: http://www.dsmit.com/cons/

_______________________________________________
address@hidden
http://mail.gnu.org/mailman/listinfo/cons-discuss
Cons URL: http://www.dsmit.com/cons/