Shell Programming and Scripting

a name1 1200
a name2 800
b name1 100
b name2 150
b name3 4

a name2 800
b name3 4

awk '{idx=$1 FS $2}FNR==1{a3[idx]=$3}{a3[idx]=(a3[idx]>$3)?a3[idx]:$3;a4[idx]=($4>a4[idx])?$4:a4[idx]} END{for(i in a3)print i,a3[i],a4[i]}' myFile

a x 1 4
a x 2 5
b x 5 10
b x 6 12
c x 8 15
c x 6 12

a x 2 5
b x 6 12
c x 8 15

awk '{idx=$1}FNR==1{a3[idx]=$2}{a3[idx]=(a3[idx]>$2)?$2:a3[idx]} END{for(i in a3)print i,a3[i]}' myFile

awk '{ 
	# duplicate is column1
	col = $1
	
	# value to be compared is from column3
	value = $3

	# Here we track for duplicate records
	rep[col]++

      }
      {
	# if column is not in array meaning array does not have index col so far
        # or column in array meaning index col is exists in array a but
	# array element is greater than current line value ($3) then 
	# modify array a 
	if(!(col in a) || ( col in a && a[col] > value))
	{
		a[col] = value
	
		# Here we set o/p required you can also write $1 OFS $2 etc
		# Used in end block
		output[value] = $0 
	}

      }
   END{
	# Loop throuh rep array
	for(i in rep)
	{
		# if array elements is greater then 1 then its duplicate 
		# so print contents from array output 
		# where index being element of array a 
		# array a index is current index i
		if(rep[i]>1 )
			print output[a[i]]
	}
      }'    file

awk '
!($1 in d) || f3[$1] > $3 {
	d[$1] = $0
	f3[$1] = $3
}
END {	for(i in d)
		print d[i]
}' myFile

a name2 800
b name3 4