Re: option for performing dry run

[Ole Tange]

On Wed, Dec 15, 2010 at 3:20 PM, Cook, Malcolm <MEC@stowers.org> wrote:
> As implemented, it seems to do what I've asked.  Thanks!

Good.

> But....thinking about it a little more.... hmmmm....
>
> You have many command line options.  Appreciating them all without having had 
> to use them all is a small challenge....

No one uses them all. Not even me. But people use different subsets of them.

> I note that parallel by default is --silent and has option to be --verbose, 
> which shows the command before executing.
>
> GNU make, onthe other hand, by default is --verbose (it prints each command 
> immediately before execution) and has option to be --silent which squelches 
> this trace.
>
> Assuming this is not going to change....

In practice it is rare that I need -v. More often I want to be able to
process the output. A simple example is the parallel grep from the
manpage:

       find . -type f | parallel -k -j150% -n 1000 -m grep -H -n STRING {}

Here I can simply treat the output as I would the output from grep.

> I think you might provide a flag to '--forgo' execution of the command, the 
> 'transfer' and/or the 'cleanup'.  Then allow -v to control what gets echoed 
> to STDOUT.
>
> This new flag would also control whether jobs are submitted to remote hosts.  
> Also, if set, files would not be transferred but (if --verbose) the commands 
> to effect the transfer ('rsync' etc) would be printed.
>
> You _might_ call the flag --forgo (-f) with default value of 'all' but option 
> to set it to one or more of 'transfer' 'return' 'cleanup'.
>
> --dry-run is then equivilent to '--verbose --forgo all'

With your description it is not clear to me what --forgo should do.

If you do not what a job sent to a remote machine, simply put only ':'
in the -S or leave -S out.


/Ole