webadmin-devel

[webmin-devel] Progressive commands

[David D. <ddr...@pu...>]

Hey guys,

I have to run a command that:
a) displays progressive output as it runs, and
b) continues to run, even if the user moves to another page

I have tried the code below, which satisfies (a) but I noticed that when I went to another page, it would stop running and so doesn't satisfy (b) as well. Note that I am only using ping as a test.

open(CMD, "ping 127.0.0.1 2>&1 |");
while(<CMD>) {
	print $_;
}
close(CMD);

Cheers,
David

Re: [webmin-devel] Progressive commands

[Antonio G. <ga...@mc...>]

David Drayton ha scritto:
> Hey guys,
>
> I have to run a command that:
> a) displays progressive output as it runs, and
> b) continues to run, even if the user moves to another page
>
> I have tried the code below, which satisfies (a) but I noticed that when I went to another page, it would stop running and so doesn't satisfy (b) as well. Note that I am only using ping as a test.
>
> open(CMD, "ping 127.0.0.1 2>&1 |");
> while(<CMD>) {
> 	print $_;
> }
> close(CMD);
>   
If you have it in background when the process is killed? :)

One short solution is: you can write the ping output to a FIFO or a temp 
file then read it with "tail -f"

Regards, Antonio Gallo


-- 
(o_   Saluti, Antonio Gallo
//\   http://www.badpenguin.org/
V_/_  IRC: agx

Re: [webmin-devel] Progressive commands

[Jamie C. <jca...@we...>]

On 20/Oct/2009 21:34 David Drayton <ddr...@pu...> wrote ..
> Hey guys,
> 
> I have to run a command that:
> a) displays progressive output as it runs, and
> b) continues to run, even if the user moves to another page
> 
> I have tried the code below, which satisfies (a) but I noticed that when I went
> to another page, it would stop running and so doesn't satisfy (b) as well. Note
> that I am only using ping as a test.
> 
> open(CMD, "ping 127.0.0.1 2>&1 |");
> while(<CMD>) {
> 	print $_;
> }
> close(CMD);

The reason it gets terminated when the user leaves the page is that
the command receives a SIGPIPE signal, which by default kills it.
The way to prevent this is to add the following line at the top of
your Perl script :

$SIG{'PIPE'} = 'IGNORE';

 - Jamie