Awk/Unix group by

1
2
3
  
$ awk -F, 'NR>1{arr[$1]++}END{for (a in arr) print a, arr[a]}' file.txt
  

joe 1

jim 1

mike 3

bob 2

EXPLANATIONS

-F, splits on ,

NR>1 treat lines after line 1

arr[$1]++ increment array arr (split with ,) with first column as key

END{} block is executed @ the end of processing the file

for (a in arr) iterating over arr with a key

print a print key , arr[a] array with a key

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