bash - Best to way to add up numbers by ids -

suppose have file, has 2 columns.

12,1 12,2 11,3 11,2 

i want add second column first column. output should this

12,3 11,5 

is there easy way on linux environments (on command line)?

$ cat file 12,1 12,2 11,3 11,2 

here awk approach:

$ awk -f, '$1 { a[$1]+=$2 } end { (i in a) { printf "%s,%d\n", i, a[i] } }' file 11,5 12,3 

and here 1 in bash:

$ cat ./id.sh #!/bin/bash  ifs=',' while read id value;         [ -n "${id}" ] || continue         (( a[id] += value )) done < file  id in "${!a[@]}";         echo "${id},${a[${id}]}" done  $ ./id.sh 11,5 12,3 

they both work same principle - read line line field/input separator set , , assemble array indexed first column - values of second column summed up. when hard work done, print array back.