Question

I got a txt format like below, each user(a,b,c…) has a numeric value

old values file

a,1000130103828
b,9230032882842
c,98247249242402
...

and new values file

a,20200203020
b,1029328428429
c,102492290011
...

How can I easily calc a new file by sum each user’s value in Bash?

Answer 1

call awk?

 awk '-F,' '{users[$1]+=$2}; END{for (u in users) {printf("%s,%s\n", u, users[u])}}' file1 file2 > sumFile

output

cat sumFile
a,1020330306848
b,10259361311271
c,98349741532413

Its likely that with more than 3 users, the output will not be sorted as it is in your file, if you need sorting, add

  | sort -t, -k1 

to the above.

IHTH.