Very Computer

Hi,

I'm wondering if I can do the following with sh shell script.

I know I can put a group of commands into background by specifying:

{ cmd1; cmd2; ... ; cmdn ; } &

Now the question is that how can I control whether to put the group of
commands in background by a variable. I.e, I wish I could do sth like
this:

 { cmd1; cmd2; ... ; cmdn ; } ${background_execution-'&'}

Sure the above is not working, but hope you get the idea -- control
whether the group of commands is executed in background by a single
variable. The point is that, if possible, I don't want to duplicate the
group into two branch of if/else clause.

Can I do that? thanks!

-- Tong
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Quote:>Now the question is that how can I control whether to put the group of
>commands in background by a variable. I.e, I wish I could do sth like
>this:

> { cmd1; cmd2; ... ; cmdn ; } ${background_execution-'&'}

>Sure the above is not working, but hope you get the idea -- control
>whether the group of commands is executed in background by a single
>variable. The point is that, if possible, I don't want to duplicate the
>group into two branch of if/else clause.

Well, it's not precisely what you're asking for, but how about
the functionally similar:
 { cmd1; cmd2; ... ; cmdn ; } &
 case ${background_execution+set} in "") wait ;; esac
?

Or, if there is some subtlety which somehow makes that
inappropriate, how about:
  eval '{ cmd1; cmd2; ... ; cmdn ; } '${background_execution-&}
?

                --Ken Pizzini

On the contrary, the 2 ways you suggested are exactly what I
was looking for. Thanks Ken, you have always been a great help!

-- Tong
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Welcome to my homepage http://members.xoom.com/suntong001/
  - All free contribution & collection
  - freeware &  music from the heavens