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Top Forums Shell Programming and Scripting perl... how to tell if a piped command is still running? Post 81224 by boytheo on Wednesday 17th of August 2005 11:01:18 AM
Old 08-17-2005
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 Smilie

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.
 

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KETCHUP(1)						      General Commands Manual							KETCHUP(1)

NAME
ketchup - Utility to update the kernel source SYNOPSIS
ketchup [options] <ver> DESCRIPTION
This tool synchronises a local kernel tree with a desired kernel version and patch set from a kernel.org mirror. The default requires a GPG key on your keyring, to verify the identity of the patches and source archives. Entire kernel images are not downloaded unless necessary, so bandwidth is saved. Patches are applied and removed as necessary to attain the requested version. OPTIONS
-a --archive (~/.ketchup) cache directory -d --directory (.) directory to update -f --full-tarball if unpacking a tarball, download the latest -g --gpg-path (/usr/bin/gpg) path for GnuPG -G --no-gpg disable GPG signature verification -k --kernel-url (http://www.kernel.org/pub/linux/kernel) base url for kernel.org mirror -l --list-trees list supported trees -m --show-makefile output version in makefile <arg> -n --dry-run don't download or apply patches -o --only-dl don't apply patches -p --show-previous output version previous to <arg> -q --quiet reduce output -r --rename-directory rename updated directory to linux-<v> -s --show-latest output the latest version of <arg> -u --show-url output URL for <arg> -w --wget (/usr/bin/wget) command to use for wget CONFIGURATION
Ketchup will read files named .ketchuprc in $HOME and in the target kernel directory, with the kernel directory taking precedence. A .ketchuprc file uses the Python syntax and may set the following variables: default_tree The default_tree option specifies the kernel version to work with if one is not given on the command line. precommand The precommand option specifies a command to run before synchronising the kernel tree to the required version. postcommand The postcommand option specifies a command to run after synchronising the kernel tree to the required version. AUTHOR
ketchup was written by Matt Mackall <mpm@selenic.com>. This manual page was written by Baruch Even <baruch@debian.org>, for the Debian project (but may be used by others). Description text taken from a former packaging attempt of Jack Wasey <debian@jackwasey.com>. February 16, 2010 KETCHUP(1)
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