Verify that a file has constant number of fields.

# awk -F~ '{print NF}' < 20100912PATLAB.txt | sort | uniq
25


add -c to uniq to get count of occurrences.

# awk -F'\t' '{print NF}' < PTINFO.EXT | sort | uniq -c
4420846 38
3 39
3 40
1 41
3 42