This sh script allows to compare columns from two files. It ends in error whenever two values don't match.
The calling sequence is:
compare_columns reffile[ext] newfile[ext] "column list" "comment" # reffile[ext]: name of the first file with extension number # newfile[ext]: name of the second file with extension number # "column list": names of the columns to be compared (separated by a blank) # "comment": comment used to make the output message specific