UNIX for Dummies Questions & Answers

File:
Rice Food
Carrots Food
Beans Food
Plates Kitchen
Fork Kitchen
Knives Kitchen

Food:
   Rice
   Carrots
   Beans

Kitchen:
   Plates
   Forks
   Knifes

$ cat dat.txt
Rice Food
Carrots Food
Beans Food
Plates Kitchen
Fork Kitchen
Knives Kitchen

#!/usr/bin/perl 

use strict;
use warnings;

my %list;
my $key;
my $val;

while (<>) {
	if (/^(\w*) (\w*)$/) {
		$key=$2; 
		$val=$1;
		push @{ $list{ $key } }, $val; 
	}	
}	

foreach $key (sort keys %list) { 
	print "$key:\n"; 
	foreach (sort @{ $list{$key} } ) { 
		print "\t$_\n"; 
	} 
} 

$ thatperlsc.pl dat.txt
Food:
	Beans
	Carrots
	Rice
Kitchen:
	Fork
	Knives
	Plates

#!/usr/bin/perl -W

use strict;

my %places;
while ( my $line = <DATA> ) {
    chomp $line;
    my @parts = split /\s/, $line;
    push @{ $places{ $parts[1] } }, $parts[0];
}

foreach my $place (sort keys %places) {
    print $place, " ", join( ", ", sort @{ $places{$place} } ), "\n";
}

__DATA__
Rice Food
Carrots Food
Beans Food
Plates Kitchen
Fork Kitchen
Knives Kitchen

$ cat dat.txt
Rice Food
Carrots Food
Beans Food
Plates Kitchen
Fork Kitchen
Knives Kitchen
$ awk -v pat="Food" 'BEGIN { printf pat", " } $2 ~ pat { printf $1", " }'  dat.txt | sed 's/, $//g'
Food, Rice, Carrots, Beans
$
$ awk -v pat="Kitchen" 'BEGIN { printf pat", " } $2 ~ pat { printf $1", " }'  dat.txt | sed 's/, $//g'
Kitchen, Plates, Fork, Knives

#!/bin/ksh
FIRST_TIME="Y"
CATEGORY_PREV="XXXXX"
ITEM_LIST=""
#
awk '{print $2,$1}' filename|while read CATEGORY ITEM
do
        # First time through?
        if [ "${FIRST_TIME}" = "Y" ]
        then
                ITEM_LIST="${ITEM}"
                CATEGORY_PREV="${CATEGORY}"
                FIRST_TIME="N"
                continue
        fi
        #
        # Same category?
        if [ "${CATEGORY}" = "${CATEGORY_PREV}" ]
        then
                ITEM_LIST="${ITEM_LIST}, ${ITEM}"
                continue
        fi
        #
        # New category
        echo "${CATEGORY_PREV} ${ITEM_LIST}"
        CATEGORY_PREV="${CATEGORY}"
        ITEM_LIST="${ITEM}"
done
#
# Output last line
if [ ! "${CATEGORY_PREV}" = "XXXXX" ]
then
        echo "${CATEGORY_PREV} ${ITEM_LIST}"
fi




Food Rice, Carrots, Beans
Kitchen Plates, Fork, Knives