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


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting perl... how to tell if a piped command is still running?
# 1  
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.
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... (4 Replies)
Discussion started by: hagaysp
4 Replies

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 Replies)
Discussion started by: SkySmart
3 Replies

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... (2 Replies)
Discussion started by: ConcealedKnight
2 Replies

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 ) { ... (7 Replies)
Discussion started by: zaxxon
7 Replies

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... (4 Replies)
Discussion started by: sam05121988
4 Replies

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 (2 Replies)
Discussion started by: dplinux
2 Replies

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? (2 Replies)
Discussion started by: bharadiaam
2 Replies

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 (1 Reply)
Discussion started by: aju_kup
1 Replies

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? (5 Replies)
Discussion started by: krishmaths
5 Replies
Login or Register to Ask a Question
lorder(1)						      General Commands Manual							 lorder(1)

NAME
lorder - Finds the best order for member files in an object library SYNOPSIS
lorder file... DESCRIPTION
The lorder command is essentially obsolete. Use the following command in its place: % ar -ts file.a The lorder command reads one or more object or library archive files, looks for external references, and writes a list of paired filenames to standard output. The first of each pair of files contains references to identifiers that are defined in the second file. You can send this list to the tsort command to find an ordering of a library member file suitable for 1-pass access by ld. If object files do not end with lorder overlooks them and attributes their global symbols and references to some other file. EXAMPLES
To create a subroutine library, enter: lorder charin.o scanfld.o scan.o scanln.o | tsort | xargs ar qv libsubs.a (Enter this command entirely on one line, not on two lines as shown above.) This creates a subroutine library named libsubs.a that contains charin.o, scanfld.o, scan.o, and scanln.o. The ordering of the object mod- ules in the library is important. The lorder and tsort commands together add the subroutines to the library in the proper order. Suppose that scan.o calls entry points in scanfld.o and scanln.o. scanfld.o also calls entry points in charin.o. First, the lorder command creates a list of pairs that shows these dependencies: charin.o charin.o scanfld.o scanfld.o scan.o scan.o scanln.o scanln.o scanfld.o charin.o scanln.o charin.o scan.o scanfld.o This list is piped to the tsort command, which converts the list into the ordering that is needed: scan.o scanfld.o scanln.o charin.o Note that each module precedes the module it calls. charin.o, which does not call another module, is last. The second list is then piped to xargs, which constructs and runs the following ar command: ar qv libsubs.a scan.o scanfld.o scanln.o charin.o This ar command creates the properly ordered library. FILES
Temporary files SEE ALSO
Commands: ar(1), as(1), cc(1), ld(1), make(1), nm(1), size(1), strip(1), tsort(1), xargs(1) Files: a.out(4), ar(4) lorder(1)