match and print each selection from array - perl

Question

I have a script which collects configuration data from a database and stores it in an array. I need to print find each interface and print it's config detail for a device. I will only post the parts that I need help with.
So firstly, here is an extract from the array:
track 2 interface GigabitEthernet1/6 line-protocol
!
!
!
!
!
interface Port-channel10.1
description Enclosure 1 - 3040-1b
switchport
switchport trunk encapsulation dot
switchport trunk allowed vlan 200, 202
switchport mode trunk
logging event link-status
logging event trunk-status
logging event bundle-status
logging event spanning-tree status
shutdown
interface Ethernet1/20
description tx to something
switchport mode trunk
switchport trunk allowed vlan 200-300
spanning-tree guard root
speed 1000
duplex full
interface Bundle-Ether2.1
description Bundle link to something
service-policy input qos-pol1
vrf V17:vodanet
ipv4 address 10.1.1.1 255.0.0.0
encapsulation 250
interface Ethernet1/1
description some interface desc
switchport mode trunk
switchport trunk allowed vlan 200-299
spanning-tree guard root
duplex full
no negotiate auto
clock timezone GMT 2 0
line console
terminal length 48
...
So each interface does not necessarily have the same amount of config detail following it. I basically need to take each of these interface configurations and print them individually. I will be storing these in smaller config-let flat files. So I need to print from interface ... till the last item before the next interface, but I am lost in searching. This is my latest attempt, but only works if I search for 2 different start/end strings, like so:
foreach (#array) {
if (/^interface/) {
$counter = 1;
} elsif (/duplex/) {
$counter =0;
} elsif ($counter) {
print;
}
}
The problem here is I am missing the first and last string, and not all interfaces end with duplex. I was thinking of using the beginning of line interface and then each double white space delimited items after but unsure how. Can someone please help me in finding a solution.
Edit
So to clarify array it is simply lines grabbed from a database and pushed to #array

Answer 1

The problem: An array (#lines) has "interface sections" which start with an /^interface/ line and run until the next interface line. The last section stops at the first unindented line. Parse interface sections from the array.
One way: Find indices of each interface line in the array #lines. Then elements of #lines between successive indices are the interface sections. The last one is found separately.
my #idx = grep { $lines[$_] =~ /^interface/ } 0..$#lines;
for my $i (0..$#idx-1) {
say "Interface:";
say "\t$_" for #lines[$idx[$i]..$idx[$i+1]-1];
}
# The last interface section stops at the first unindented line
say "Interface:";
for my $i ($idx[-1] .. $#lines) {
last if $lines[$i] =~ /^\S/ and $lines[$i] !~ /^interface/;
say "\t$lines[$i]";
}
The last interface segment goes until the first unindented line, as clarified in comments.
Prints "Interface:" are there only to visually distinguish sections; the lines for each interface can be added to an arrayref instead of printing, for example. Tested on the posted sample.
Another way: Iterate over #lines and for each /^interface/ line add a new arrayref to the array with all sections. Then the lines are added to that, last, arrayref. Exit on the first unindented line which isn't /^interface/
The program gets lines from the submitted file (or lines.txt), with the question's sample.
use warnings;
use strict;
use feature 'say';
use Data::Dump qw(dd);
use Path::Tiny;
my $file = shift #ARGV or 'lines.txt';
my #lines = path($file)->lines({chomp=>1});
my #if_sections; # store arrayrefs with lines for each interface
for (#lines) {
if (/^interface/) {
push #if_sections, [ $_ ]; # add arrayref for new interface
next;
}
elsif (/^\S/) { last }
push #{$if_sections[-1]}, $_; # add lines to the last arrayref
}
dd \#if_sections;
Uses the handy Path::Tiny to read the file. The module runs checks and croaks on failures.
The dd from Data::Dump is used to easily show the data structure, for convenience. This is an array with elements that are array references, so to work with it
foreach my $iface (#if_sections) {
say "Interface section:";
foreach my $line (#$iface) {
say $line;
}
}
what can be written more compactly in a number of ways.
See the tutorial perlreftut and
the complex data structure cookbook perldsc.