expanding variables in variables

actum has asked for the wisdom of the Perl Monks concerning the following question:

Hy I have this pice of code:

 @inv0 =  split(/\n/,qx'/usr/sbin/iptables -L DOWN0 -v -n -x | awk \'{
+print $8" - "$2}\' | egrep \'^192\'');
@outv0 = split(/\n/,qx'/usr/sbin/iptables -L UP0 -v -n -x | awk \'{pri
+nt $7" - "$2}\' | egrep \'^192\'');
@inv1 =  split(/\n/,qx'/usr/sbin/iptables -L DOWN1 -v -n -x | awk \'{p
+rint $8" - "$2}\' | egrep \'^192\'');
@outv1 = split(/\n/,qx'/usr/sbin/iptables -L UP1 -v -n -x | awk \'{pri
+nt $7" - "$2}\' | egrep \'^192\'');
@inv2 =  split(/\n/,qx'/usr/sbin/iptables -L DOWN2 -v -n -x | awk \'{p
+rint $8" - "$2}\' | egrep \'^192\'');
@outv2 = split(/\n/,qx'/usr/sbin/iptables -L UP2 -v -n -x | awk \'{pri
+nt $7" - "$2}\' | egrep \'^192\'');
[download]

so how can i make this in an for structure to avoid repetition? I have tried with arrays in arrays but no succes. Second I do not know how to expand an variable in an qx section.

Comment on expanding variables in variables Download Code

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Re: expanding variables in variables by revdiablo (Prior) on May 22, 2006 at 16:18 UTC
First, I'd like to note that the guts of your pipeline can be replaced by pure Perl code. All you really need to call is the `iptables` command. That said, the reason you're not getting Perl variables interpolated into your qx is because you're using single quotes as the delimiter. Try this instead: `for (0 .. 2) { my $output = qx{echo '\$_ is $_'}; print $output; }` [download] As for moving that into a better data structure, my first thought is an array of arrays, but the exact structure you'll want really depends on what you want to do with it: `my @things; for (0 .. 2) { my @inv = ...; my @outv = ...; push @things, [ \@inv, \@outv ]; }` [download]	[reply] [d/l] [select]
Re: expanding variables in variables by QM (Parson) on May 22, 2006 at 16:57 UTC
Can't you drop the `split` with `qx`? In scalar context, it comes back as a single (potentially multi-line) string, or undef if the command failed. In list context, returns a list of lines (however you've defined lines with $/ or $INPUT_RECORD_SEPARATOR), or an empty list if the command failed. -QM -- Quantum Mechanics: The dreams stuff is made of	[reply] [d/l] [select]
Re^2: expanding variables in variables by suaveant (Parson) on May 22, 2006 at 18:14 UTC
Yup, but then the \n is still at the end of each line then, so you need to chop or chomp the array to get the same result. - Ant - Some of my best work - (1 2 3)	[reply]