Shell Programming and Scripting

cat file.txt | transpose_grep 'C'

cat file.txt | transpose_grep 'B'

$ ruby -ane 'BEGIN{h={}};$F.each_with_index{|x,y|h[y+1]=x} if $.==1; h.select {|k,v| print "#{$F[k-1]} " if v == "B"} and puts if $.>1 ' file
2 5
7 0
6 9
3 0

$ ruby -ane 'BEGIN{h={}};$F.each_with_index{|x,y|h[y+1]=x} if $.==1; h.select {|k,v| print "#{$F[k-1]} " if v == "C"} and puts if $.>1 ' file
3
8
7
8

use strict;
use warnings;

open(F, '<', 'a') or die;

my $data;
$data = <F>;
chomp($data);
my $cnt = 0;
foreach my $d ( split(/  */, $data) ) {
    last if ( $d =~ /$ARGV[0]/ );
    $cnt++;
}

print $ARGV[0], "\n";
while ( $data = <F> ) {
    chomp($data);
    my $val = (split(/  */, $data))[$cnt];
    print $val, "\n";
}

close(F);

perl -lane'BEGIN { $k = shift }
  @cols = grep $F[$_] eq $k , 0..@F 
    if $. == 1; 
  print "@F[@cols]"
  ' <pattern> infile

% perl -lane'BEGIN { $k = shift }
  @cols = grep $F[$_] eq $k , 0..@F
    if $. == 1;
  print "@F[@cols]"
  ' B infile 
B B
2 5
7 0
6 9
3 0
% perl -lane'BEGIN { $k = shift }
  @cols = grep $F[$_] eq $k , 0..@F
    if $. == 1;
  print "@F[@cols]"
  ' C infile 
C
3
8
7
8

var=B
awk -v s=$var '
NR==1 {for (i=1;i<=NF;i++) if ($i==s) a[++j]=i}
{for (i=1;i<=j;i++) printf $a[i] FS;printf RS}
' infile