Shell Programming and Scripting

15|69
15|70
15|71
15|72
15|73
15|74
16|2
16|3
16|4
16|5
16|6
16|7
16|8
16|9
16|10
16|11
16|12
16|13
16|14
16|15
16|16
16|17
16|18
16|19
16|20
16|21
17|2
17|3
19|2
19|3

15|74
16|21
17|3
19|3

nawk '
  BEGIN { FS=OFS="|" }
  { if ($2 > a[$1]) a[$1]=$2 }
  END { for(i in a) print i, a[i]}' myFile

sort -t\| -nrsk2 file1 | awk -F\| '!A[$1]++'

# cat justdoit
 
#!/bin/bash
 
oldIFS=$IFS
IFS="|"
i=0 ; ix=0 ; in=0
exec <$1
 
while read val1 val2
  do
    array[i]=$val1
    let i=i+1
    tmpval[i]=$val2
     if [ $i -ne 1 ] ; then
        if [ ${array[ix]} -ne ${array[ix+1]} ] ; then
           myval2[in]=${tmpval[i-1]}
             ((++in))
        fi
             ((++ix))
     fi
  done
myval2[in]=${tmpval[i]}
 
IFS=$oldIFS
count=${#array[@]}
in=0  ; inx=0
 
myval[0]=${array[0]}
 
while [ $(( count -=1 )) -gt -1 ]
  do
   same=1
    for val in ${array[@]}
     do
       if [ $val -eq ${array[in]} ] ; then
           ((++same))
       fi
     done
 
  var=ok
 
   if [ $same -gt 2 ] ; then
    for newval in ${myval[@]}
      do
        if [ ${array[in]} -ne $newval ] ; then
          var=notok
        else
          var=ok
        fi
      done
 fi
 
 if [ "$var" == "notok" ] ; then
       myval[inx]=${array[in]}
 fi
 
((++in))
((++inx))
  done
 
inx=0
for val1 in ${myval[@]}
   do
     echo "$val1|${myval2[inx]}"
        ((++inx))
   done

# cat myfile
15|69
15|70
15|71
15|72
15|73
15|74
16|2
16|3
16|4
16|5
16|6
16|7
16|8
16|9
16|10
16|11
16|12
16|13
16|14
16|15
16|16
16|17
16|18
16|19
16|20
16|21
17|2
17|3
19|2
19|3

# ./justdoit myfile
15|74
16|21
17|3
19|3