Forum: Ruby App not waiting for popen to finish

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7d77e3e44327ffd20c0d19fa0fe15cab?d=identicon&s=25 |MKSM| (Guest)
on 2006-04-11 07:33
(Received via mailing list)
Hello,

I'm using 'wget' to download a few files and then tar them up. I'm
using popen to make calls to wget and tar. Problem is that it tries to
call tar right after the wget call. I need to wait for wget to finish.
Here is what i've got so far.

categories = [...]

categories.each_with_index { |url,i|
  IO.popen("wget -r -np -l 0 -w 4 #{url}")
  IO.popen("tar -zcf public_html/category_#{i}.tar.gz files")
}

Thanks in advance.

Ricardo
E34b5cae57e0dd170114dba444e37852?d=identicon&s=25 Logan Capaldo (Guest)
on 2006-04-11 07:48
(Received via mailing list)
On Apr 11, 2006, at 1:31 AM, |MKSM| wrote:

>   IO.popen("wget -r -np -l 0 -w 4 #{url}")
>   IO.popen("tar -zcf public_html/category_#{i}.tar.gz files")
> }
>
> Thanks in advance.
>
> Ricardo
>

The solution would be to do

IO.popen("...")
Process.wait

However since you aren't apparently even using the IO capabilities of
popen, why not simply make use of system? It will automatically wait
for the process to exit
e.g.

system("wget -r -np -l 0 -w 4 #{url}")
  Of course if the only reason you are using IO.popen is to prevent
output to the console you can do
system("wget -r -np -l 0 -w 4 #{url} 2>&1 >/dev/null")
Or even:

Process.wait Process.fork { STDOUT.reopen("/dev/null", "w");
STDERR.reopen("/dev/null", "w"); exec("wget -r -np -l 0 -w 4 #{url}") }
Cb48ca5059faf7409a5ab3745a964696?d=identicon&s=25 unknown (Guest)
on 2006-04-11 15:35
(Received via mailing list)
On Tue, 11 Apr 2006, |MKSM| wrote:

>  IO.popen("wget -r -np -l 0 -w 4 #{url}")
here you have a pipe that's been returned.  wget is writing to it.  you
simply
need to read all of wget's output and close the pipe:

   IO.popen("wget -r -np -l 0 -w 4 #{url}"){|pipe| pipe.read}

>  IO.popen("tar -zcf public_html/category_#{i}.tar.gz files")
> }
>
> Thanks in advance.
>
> Ricardo
>
>

-a
7d77e3e44327ffd20c0d19fa0fe15cab?d=identicon&s=25 |MKSM| (Guest)
on 2006-04-11 16:03
(Received via mailing list)
Thanks for your suggestion. I'm going with the last one using a block
with popen. That way i can easily send the output to a logfile.

Best Regards,

Ricardo
Cb48ca5059faf7409a5ab3745a964696?d=identicon&s=25 unknown (Guest)
on 2006-04-11 16:18
(Received via mailing list)
On Tue, 11 Apr 2006, |MKSM| wrote:

> Thanks for your suggestion. I'm going with the last one using a block
> with popen. That way i can easily send the output to a logfile.
>
> Best Regards,

fyi.  you still need to call Process.wait if you also want the status.
with
my session lib you can do this as

   require 'session'

   sh = Session::SH::new

   stdout, stderr = '', ''
   append = lambda{|o,e| stdout << o if o; stderr << e if e}

   status =
     sh.execute("wget -r -np -l 0 -w 4 #{url}", &append)

   status =
     sh.execute("tar -zcf public_html/category_#{i}.tar.gz files",
&append)

where stdout and stderr can be anything that supports '<<'.  the above
starts
only one child process as well.

regards.

-a
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