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

Login or Register to Ask a Question and Join Our Community

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

Tags

Login to Discuss or Reply to this Discussion in Our Community

Top Forums Shell Programming and Scripting perl... how to tell if a piped command is still running?

08-17-2005

Registered User

1, 0

Join Date: Aug 2005

Last Activity: 17 August 2005, 7:29 PM EDT

Posts: 1

Thanks Given: 0

Thanked 0 Times in 0 Posts

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

View Public Profile for boytheo

Find all posts by boytheo

Login or Register to Ask a Question

Previous Thread | Next Thread

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Passing an argument using alias to piped command

Hi. I'm trying to do a "simple" thing. grep -rls grepped_exp path | xgs where xgs is an alias to something like: xargs gvim -o -c ":g/grepped_exp" now the problem is that I want to pass the "grepped_exp" to the piped alias. I was able to do something like what I want without the...

2. Programming

Running java script from piped output

to run most other scripts through a pipe, something similar to the following is usually enough: cat script.sh | sh cat perl.pl | perl -- "<arguments" However, for javascript command line scripts, i cant seem to get this to work. Any ideas? cat hull.js #!/usr/bin/js ...

3. Shell Programming and Scripting

Can't Output Piped Perl In-line command to a File

Hello, I'm pretty stumped, and I don't know why I am not able to redirect the output to the 'graphme' file with the command below in Fedora 18. tcpdump -l -n -t "tcp == 18" | perl -ane '($s,$j)=split(/,/,$F,2); print "$s\n";' > graphme In case you're wondering, I was following the example...

4. Shell Programming and Scripting

Perl: How to check if there is something being piped in

Hi, I am somewhat new to Perl and currently checking it out. I have a problem testing, if there is nothing being piped in to that script. I am reading input from STDIN this way: while( defined($line = <STDIN>) ) { chomp($line); if( $line =~ m/($ARGV)/g ) { ...

5. Shell Programming and Scripting

Trouble executing piped shell commands in perl code

I am trying to execute a piped combination of shell commands inside a perl program. However, it is not working as desired. This is my program, i am trying to print only filenames from the output of ls -l $ cat list_test #!/usr/bin/perl -w use strict; my $count=0; my @list=`ls -l|awk...

6. Shell Programming and Scripting

running shell command in Perl script

Does not work. #!/usr/bin/perl $etcdir = 'ls -l /etc'; print $etcdir; #END ------------result-------- #perl -w abc123.pl ls -l /etc # This method works. #!/usr/bin/perl $etcdir = system("ls -l /etc"); print $etcdir; #END

7. Shell Programming and Scripting

How to execute piped command using exec or system

Hi All, I want to execute a piped command like 'ls /opt | grep xml' using array as parameters list. How can I do that?

8. Shell Programming and Scripting

perl for running ps -ef command

I have following script $cmd="ps -ef |"; open(PSINFO, $cmd) || die "Unable to get ps -ef information from System"; while running script with above lines, it is showing following err ps: illegal option -- f usage: ps

9. Shell Programming and Scripting

Return value of piped command?

grep $SEARCH_STRING /etc/passwd | cut -d":" -f 1,5 I need to check the $? value of grep in the above. If I place a test for $? after the above piped command, it returns success status of grep piped to cut. How can I get the success status of grep alone?

Login or Register to Ask a Question

LEARN ABOUT OSX

platform::shell

platform::shell(n)					       Tcl Bundled Packages						platform::shell(n)

__________________________________________________________________________________________________________________________________________________

NAME

       platform::shell - System identification support code and utilities

SYNOPSIS

       package require platform::shell ?1.1.4?

       platform::shell::generic shell
       platform::shell::identify shell
       platform::shell::platform shell
_________________________________________________________________

DESCRIPTION

       The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.

       This  package  allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
       requirement is that the other shell (identified by its path), is actually executable on the current machine.

       While for most platform this means that the architecture of the interrogated shell is identical to the architecture of  the  running  shell
       this  is  not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
       32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.

       For applications like a code repository it is important to identify the architecture of the shell which will  actually  run  the  installed
       packages, versus the architecture of the shell running the repository software.

COMMANDS

       platform::shell::identify shell
	      This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::generic shell
	      This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::platform shell
	      This command returns the contents of tcl_platform(platform) for the specified Tcl shell.

KEYWORDS

       operating system, cpu architecture, platform, architecture

platform::shell 						       1.1.4							platform::shell(n)