Shell Programming and Scripting

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unset k v
( sort in_file
  echo EOF # force last set out of while
 ) | while read k v
do
 if [ "$lk" = "" ]
 then
  lk="$k" lv="$v"
  continue
 fi
 if [ "$k" != "$lk" ]
 then
  echo "$lk $lv"
  lk="$k" lv="$v"
 fi
 lv="$lv $v"
done >out_file

typeset -A ht
while read k v
do
 ht[$k]="${ht[$k]} $v"
done <in_file
for k in "${!ht[@]}"
do
 echo "$k${ht[$k]}"
done >out_file

awk '{a[$1] = a[$1] " " $2;}END{for(i in a)if(a[i] ~ / .* /)print i a[i];}' infile | sort -nr

perl -alne  '{$h{$F[0]}.=" ".$F[1];}END{foreach $i (sort keys %h){print $i." ".$h{$i};}}' input_file