perl... how to tell if a piped command is still running?

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08-17-2005

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perl... how to tell if a piped command is still running?

I'm using the fabulous perl. I need a way to tell when a piped call to "open" has completed. Can I do this with a command like <ShellPipe> ??

Reason behind this:

I'm trying to write a backup script in perl! This script will download a certain file from my web server, to my computer.

Now, this perl script calls wget something like this:

open( ShellPipe, "wget http://url.com" );

Is there some way to get wget to delete the file if the file download got interupted? Otherwise I'll have a partially downloaded backup!

My script is smart enough, that it will try again if the file doesn't exist, you see. But what if the download got interupted? Then a file will exist, and I'll have a bad backup.

I know it's unlikely to get interupted, but I like to take care and be very sure of these things

Also, my webserver does not tell me the size of the file to be downloaded. It tells you when there is no more data, though.

So for this reason, I just need to tell when the pipe has been completed.

boytheo

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LEARN ABOUT DEBIAN

funnel

funnel(1)							     logtools								 funnel(1)

NAME

       funnel - split one pipe stream to one or more files or programs

SYNOPSIS

       funnel [|] [>[>]file] [|process]

DESCRIPTION

       The funnel program will read data from standard input and write it to several output streams.

       The | symbol means to copy standard input to standard output.

       The > symbol means that a file name immediately follows with no separating spaces, the file will be truncated if it exists or created if it
       doesn't. The >> means that the file is to be appended to if it exists.

       A | symbol followed immediately by text indicates a command that is to be run by system() and will have all input piped to it.

EXIT STATUS

       0 No errors

       1 Error opening input

       Other errors are 100 + number of commands or files that fail

AUTHOR

       This program, its manual page, and the Debian package were written by Russell Coker <russell@coker.com.au>.

FEATURES

       Uses popen (3) for output so that shell expansion gets performed.  If you want such shell expansion then you must ensure that you quote the
       parameters correctly so that they get expanded by popen (3) not the shell that calls funnel.

SEE ALSO

       popen(3)

Russell Coker <;russell@coker.com.au>				       0.06								 funnel(1)