Hello All,

I just wanted to know what are the different ways of using commands in combination.

The most common one which i know is using pipes.
Also grouping is also done like ( ls; date) where output of both the commands is displayed.

Are there any other ways of combining various commands and using them on command line or in the scripts.

Thanks,
Rahul

Hi,

The OR (||) and AND (&& ) operators can be used as well:

ls foo && cat foo

cat foo is only executed when ls foo has no errors (in this case, foo must exist)

ls foo || touch foo

touch foo is executes only when ls foo has an error (does not exist in this example)

Hope this helps.

__________________

The dead stay dead and the living only wait to join them........

Thanks for that help.

Also if there are any more alternatives, please keep telling me.
If any links regrding this subject are available, please tell me.

I also wnated to know if all the commands can be used for command substitution using back quotes ``.
Are there any commands which cannot be used in substitution.

Thanks,
Rahul