#!/usr/bin/awk -f
# Extracts the first sentence in a text. 
# The first sentence ends when we encounter a period
# followed by a space, tab, or end of line.

{ all = all $0; }

/\.( |\t|$)/ { exit; }

END {
  sub( /\.( |\t|$).*/, ".", all );
  print all;
}