#!/usr/bin/awk -f
# HP 2013-07-29
# HP 2019-07-06 using $0, ignoring 1st line
# HP 2019-07-06 print FIRST & LAST, options for position of counter
# HP 2021-11-23 check for increase
# usage:
#   ls img_????.jpg | chkcntposinc
#   ls Track_*.gpx | chkcntposinc sta=7 len=3
BEGIN {
  sta = 5
  len = 4
}
{
  prv = cur
  cur = $0
  if (NR >= 1 && substr(prv,sta,len)+0 >= substr(cur,sta,len)+0) {
    print "NOT INC: " prv " -> " cur
  }
}
#--