Shell Programming and Scripting

apple	banana
apple	apple
apple	grapes
grapes	banana
grapes	melon
grapes	orange
grapes	cherry
orange	apple
orange	banana
banana	cherry

grapes	banana
grapes	melon
grapes	orange
grapes	cherry
apple	banana
apple	apple
apple	grapes
orange	apple
orange	banana
banana	cherry

awk '{a[$1]++}END{for (i in a) {print i,a[i]}}' data|sort -k2 -nr|awk '{print $1}'|xargs -i ksh -c 'grep "^{}" data'

cat data
apple   banana
apple   apple
apple   grapes
grapes  banana
grapes  melon
grapes  orange
grapes  cherry
orange  apple
orange  banana
banana  cherry

awk '{a[$1]++}END{for (i in a) {print i,a[i]}}' data|sort -k2 -nr|awk '{print $1}'|xargs -i ksh -c 'grep "^{}" data'
xargs: ksh: No such file or directory

xargs -i /bin/ksh -c 'grep "^{}" data'

xargs -i /bin/sh -c 'grep "^{}" data

#!/usr/bin/perl
use strict;
use warnings;

my %fruit_salad;
while(<DATA>){
    chomp;
    my ($main,$side)=split/\s+/,$_;
    push @{$fruit_salad{$main}},$side;
}
for my $main (sort {scalar @{$fruit_salad{$b}} <=> scalar @{$fruit_salad{$a}} } keys %fruit_salad ){
    for my $side (@{$fruit_salad{$main}}){
         print "$main\t$side\n";
    }
}



__DATA__
apple   banana
apple   apple
apple   grapes
grapes  banana
grapes  melon
grapes  orange
grapes  cherry
orange  apple
orange  banana
banana  cherry

awk '{if(!x[$1])x[$1]=++y;z=x[$1];a[z]++;b[z]=b[z]","$2;m[z]=$1}
END{n=asort(a,d);for(i=n;i>0;i--){for(j in a){if(a[j]==d[i]){split(b[j],c,",");f=2;for(k=a[j];k>0;k--)print m[j],c[f++];a[j]=-1}}}}' input_file