Group a list of numbers into discrete buckets

bucket.awk

# Round to the nearest multiple of "size"
function bucket(a) {
  return int((a + (size/2)) / size) * size;
}

{ buckets[bucket($1)]++ }

END {
  for (b in buckets) {
    print b, buckets[b]
  }
}

bucket.sh

#!/bin/bash

size="$1"
shift

if ! [ "$size" -eq "$size" ] 2>/dev/null; then
    echo "Bucket size must be a number" >&2
    exit 1
fi

awk -v size="$size" -f bucket.awk "$@"

Example usage:

cat ids
123
342
546
567
352
234
234
567

bucket 10 ids
550 1
570 2
340 1
350 1
120 1
230 2

Separated out the Shell script and the Awk script in order to be able to pass awk params to the script, e.g.:

bucket 10 -v 'OFS=,' ids
550,1
570,2
340,1
350,1
120,1
230,2