[SOLVED] how to merge rows ina csv file if if the first column is same in bash

how to merge rows ina csv file if if the first column is same in bash

I have written a program to find the open ports of a given IP. since the print function is in a loop my output format is like this:

IP1,22
IP1,23
IP1,24
IP2,25
IP2,26
IP3,27
IP3,30
IP3,45

How do I get it in this format:

IP1,22,23,24
IP2,25,26
IP3,27,30,45

EDIT: this is what I have done so far

awk'{a[$1]=(a[$1])? a[$1]r : r }

but I dont know how to progress forward from here.

Solution

Kindly always do add your efforts in your question in code tags. If you are not worried for order of output then try following.

awk 'BEGIN{FS=OFS=","} {a[$1]=($1 in a ? a[$1] OFS : "") $2} END{for(i in a){print i,a[i]}}'  Input_file

In case you need to get output in same order in which 1st field of Input_file is coming then try following.

awk '
BEGIN{
  FS=OFS=","
}
!b[$1]++{
  c[++count]=$1
}
{
  a[$1]=($1 in a ? a[$1] OFS : "") $2
}
END{
  for(i=1;i<=count;i++){
    print c[i],a[c[i]]
  }
}'  Input_file

Since later OP found out control-m characters were found in Input_file(s) too so adding following:

tr -d '\r' < Input_file > temp && mv temp Input_file