Perl: How to print next line after matching a pattern? - perl

Question

I would like to print specific data after matching a pattern or line. I have a file like this:
#******************************
List : car
Design: S
Date: Sun 10:10
#******************************
b-black
g-green
r-red
Car Type No. color
#-------------------------------------------
N17 bg099 g
#-------------------------------------------
Total 1 car
#******************************
List : car
Design: L
Date: Sun 10:20
#******************************
b-black
g-green
r-red
Car Type No. color
#-------------------------------------------
A57 ft2233 b
#-------------------------------------------
Total 1 car
#******************************
List : car
Design: M
Date: Sun 12:10
#******************************
b-black
g-green
r-red
Car Type No. color
#-------------------------------------------
L45 nh669 g
#-------------------------------------------
Total 1 car
#. .
#. .
#.
#.
I want to print the data for example after the lines "Type...." and dashes line"------" which is N17 and bg099. I have tried this but it cannot work.
my #array;
While (#array = <FILE>) {
foreach my $line (#array) {
if ($line =~ m/(Car)((.*))/) {
my $a = $array[$i+2];
push (#array, $a);
}
if ($array[$i+2] =~ m/(.*)\s+(.*)\s+(.*)/) {
my $car_type = "$1";
print "$car_type\n";
}
}
}
Expected Output:
Car Type No.
N17 bg099
A57 ft2233
L45 nh669
.. ..
. .

Answer 1

while (<FILE>) { #read line by line
if ($_ =~ /^Car/) { #if the line starts with 'Car'
<FILE> or die "Bad car file format"; #read the first line after a Car line, which is '---', in order to get to the next line
my $model = <FILE>; #assign the second line after Car to $model, this is the line we're interested in.
$model =~ /^([^\s]+)\s+([^\s]+)/; #no need for if, assuming correct file format #capture the first two words. You can replace [^\s] with \w, but I prefer the first option.
print "$1 $2\n";
}
}
Or if you prefer a more compact solution:
while (<FILE>) {
if ($_ =~ /^Car/) {
<FILE> or die "Bad car file format";
print join(" ",(<FILE> =~ /(\w+)\s+(\w+)/))."\n";
}
}

Answer 2

Here's another option:
use strict;
use warnings;
print "Car Type\tNo.\n";
while (<>) {
if (/#-{32}/) {
print "$1\t$2\n" if <> =~ /(\S+)\s+(\S+)/;
<>;
}
}
Output:
Car Type No.
N17 bg099
A57 ft2233
L45 nh669
Usage: perl script.pl inFile [>outFile]
Edit: Simplified

Answer 3

I got your code to work with a couple small tweaks.
It's still not perfect but it works.
"while" should be lower case.
You never increment $i.
The way you reuse #array is confusing at best, but if you just output $a you'll get your car data.
Code:
$file_to_get = "input_file.txt";
open (FILE, $file_to_get) or die $!;
my #array;
while (#array = <FILE>) {
$i = 0;
foreach my $line (#array) {
if ($line =~ m/(Car)((.*))/) {
my $a = $array[$i+2];
push (#array, $a);
print $a;
}
$i++;
}
}
close(FILE);

Answer 4

Something like this:
while (my $line = <>) {
next unless $line =~ /Car\s+Type/;
next unless $line = <> and $line =~ /^#----/;
next unless $line = <>;
my #fields = split ' ', $line;
print "#fields[0,1]\n";
}

Answer 5

a shell one-liner to do the same thing
echo "Car Type No. "; \
grep -A 2 Type data.txt \
| grep -v -E '(Type|-)' \
| grep -o -E '(\w+ *\w+)'

Answer 6

perl -lne 'if(/Type/){$a=<>;$a=<>;$a=~m/^([^\s]*)\s*([^\s]*)\s/g; print $1." ".$2}' your_file
tested:
> perl -lne 'if(/Type/){$a=<>;$a=<>;$a=~m/^([^\s]*)\s*([^\s]*)\s/g; print $1." ".$2}' temp
N17 bg099
A57 ft2233
L45 nh669
if you want to use awk,you can do this as below:
> awk '/Type/{getline;if($0~/^#---*/){getline;print $1,$2}}' your_file
N17 bg099
A57 ft2233
L45 nh669

Answer 7

Solution using Perl flip-flop operator. Assumption from the input that you always have Total line at the end of the block of interest
perl -ne '$a=/^#--/;$b=/^Total/;print if(($a .. $b) && !$a && !$b);' file