cmd1 | gzip -f ... && cmd2 : Command concatenation with condition: Execute cmd2 only if cmd1 (or gzip) fails/succeeds?

I am not sure about on how to specify that a second command should only be execute in case
that the first command fails/succeeds.

When I enter:

cmd1 | gzip -f ... && cmd2

Is then cmd2 executed only if cmd1 is finished successfully or if gzip is finished successfully?

Is the command concatenation "&&" correct at all?

What if I want cmd2 only to execute if both (cmd1 and gzip) end successfully?

What about the other way: cmd2 should only be executed if

a) cmd1 failed

b) cmd1 or gzip failed?

Matthew

On 2008-06-17, Matthew Lincoln <(E-Mail Removed)> wrote:
>
>
> I am not sure about on how to specify that a second command should
> only be execute in case that the first command fails/succeeds.
>
> When I enter:
>
> cmd1 | gzip -f ... && cmd2
>
> Is then cmd2 executed only if cmd1 is finished successfully or if gzip
> is finished successfully?
>
> Is the command concatenation "&&" correct at all?
>
> What if I want cmd2 only to execute if both (cmd1 and gzip) end
> successfully?
>
> What about the other way: cmd2 should only be executed if
>
> a) cmd1 failed
>
> b) cmd1 or gzip failed?
>
> Matthew

Use bash and test the PIPESTATUS array.

On Tue, 17 Jun 2008 06:16:24 +0000, Matthew Lincoln rearranged some
electrons to say:

> I am not sure about on how to specify that a second command should only
> be execute in case that the first command fails/succeeds.
>
> When I enter:
>
> cmd1 | gzip -f ... && cmd2
>
> Is then cmd2 executed only if cmd1 is finished successfully or if gzip
> is finished successfully?
>
> Is the command concatenation "&&" correct at all?
>
> What if I want cmd2 only to execute if both (cmd1 and gzip) end
> successfully?
>
> What about the other way: cmd2 should only be executed if
>
> a) cmd1 failed
>
> b) cmd1 or gzip failed?
>
> Matthew

Didn't you read the responses the first time you posted this question 3
days ago?

Seems like you would be better off writing a small script to do what you
want.

man bash

Greetings.

In article <485756b8$0$6616$(E-Mail Removed)>, Matthew
Lincoln wrote:
> I am not sure about on how to specify that a second command should only
> be execute in case that the first command fails/succeeds.
>
> When I enter:
>
> cmd1 | gzip -f ... && cmd2
>
> Is then cmd2 executed only if cmd1 is finished successfully or if gzip is
> finished successfully?
>
> Is the command concatenation "&&" correct at all?
>
> What if I want cmd2 only to execute if both (cmd1 and gzip) end
> successfully?
>
> What about the other way: cmd2 should only be executed if
>
> a) cmd1 failed
>
> b) cmd1 or gzip failed?

This is pretty trivial to test empirically on your own:

$ true | false && echo foo
$ false | true && echo foo
foo
$ true | true && echo foo
foo
$ false | false && echo foo
$

--
_
_V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
/ |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
(7_\\ http://www.nothingisreal.com/ >< To finish what you

Or test the value of $?
--
Guillaume Dargaud
http://www.gdargaud.net/