Exiting from sleep within a .bashrc function

Within my .bashrc, I have the following function which I would like to
exit from sleep, if Control-C is pressed.
However, nothing I have tried has worked. Every time it proceeds onto
the "ls" command.

I am attempting to trap the signal within a sub-shell by doing this:

dosomething()
{
( trap 'echo "You INTERRUPTED me";exit' SIGINT ; sleep
5 )
ls
}

This comes close to working because I can see the message when it runs
if I put in another sleep, e.g.

dosomething()
{
( trap 'echo "You INTERRUPTED me";sleep 2; exit' SIGINT ;
sleep 5 )
ls
}

But it still ignores the exit and moves onto the "ls". The question
is why?

I have found a workaround by doing this:

sleep 5 && ls

But I would still love to know why "exit" won't exit in my function.
Thanks in advance.

On 2008-08-26, jaredsubman-at-yahoo.com wrote:
> Within my .bashrc, I have the following function which I would like to
> exit from sleep, if Control-C is pressed.
> However, nothing I have tried has worked. Every time it proceeds onto
> the "ls" command.
>
> I am attempting to trap the signal within a sub-shell by doing this:
>
> dosomething()
> {
> ( trap 'echo "You INTERRUPTED me";exit' SIGINT ; sleep
> 5 )
> ls
> }
>
> This comes close to working because I can see the message when it runs
> if I put in another sleep, e.g.
>
> dosomething()
> {
> ( trap 'echo "You INTERRUPTED me";sleep 2; exit' SIGINT ;
> sleep 5 )
> ls
> }
>
> But it still ignores the exit and moves onto the "ls". The question
> is why?
>
> I have found a workaround by doing this:
>
> sleep 5 && ls
>
> But I would still love to know why "exit" won't exit in my function.

It is; it is exiting from the subshell you invoked with ( ... ).

--
Chris F.A. Johnson, author
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence

On Aug 26, 4:51*pm, "Chris F.A. Johnson" wrote:
> On 2008-08-26, jaredsub...@yahoo.com wrote:
> > Within my .bashrc, I have the following function which I would like to
> > exit from sleep, if Control-C is pressed.
> > However, nothing I have tried has worked. *Every time it proceeds onto
> > the "ls" command.
>
> > I am attempting to trap the signal within a sub-shell by doing this:
>
> > dosomething()
> > {
> > * * * *( trap 'echo "You INTERRUPTED me";exit' SIGINT ; sleep
> > 5 )
> > * * * * ls
> > }
>
> > This comes close to working because I can see the message when it runs
> > if I put in another sleep, e.g.
>
> > dosomething()
> > {
> > * * * * ( trap 'echo "You INTERRUPTED me";sleep 2; exit' SIGINT;
> > sleep 5 )
> > * * * * ls
> > }
>
> > But it still ignores the exit and moves onto the "ls". * The question
> > is why?
>
> > I have found a workaround by doing this:
>
> > sleep 5 && ls
>
> > But I would still love to know why "exit" won't exit in my function.
>
> * *It is; it is exiting from the subshell you invoked with ( ... ).
>
> --
> * *Chris F.A. Johnson, author * * *
> * *Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
> * *===== My code in this post, if any, assumes the POSIX locale
> * *===== and is released under the GNU General Public Licence

Yes, but it won't exit the function entirely so that "ls" won't
execute. The question, then is, how do I make that happen?

On Wednesday 27 August 2008 14:59, jaredsubman-at-yahoo.com wrote:

>> > I am attempting to trap the signal within a sub-shell by doing this:
>>
>> > dosomething()
>> > {
>> > ( trap 'echo "You INTERRUPTED me";exit' SIGINT ; sleep
>> > 5 )
>> > ls
>> > }

You are putting the trap code in (), so it's executed in a subshell,
and "exit" exits that subshell. But see below.

>> > But I would still love to know why "exit" won't exit in my function.
>>
>> It is; it is exiting from the subshell you invoked with ( ... ).
>
> Yes, but it won't exit the function entirely so that "ls" won't
> execute. The question, then is, how do I make that happen?

From man bash:

"Command substitution, commands grouped with parentheses, and
asynchronous commands are invoked in a subshell environment"

so, it seems that the trap code is executed in a subshell anyway.

--
All the commands are tested with bash and GNU tools, so they may use
nonstandard features. I try to mention when something is nonstandard (if
I'm aware of that), but I may miss something. Corrections are welcome.