reflow

#!/usr/bin/awk -f
#
# NAME
#
#   reflow - reformat text to one paragraph per line
#
# SYNOPSIS
#
#   reflow [<file>...]
#
# DESCRIPTION
#
#   reflow scans the supplied (text) files and reformats them such that
#   each paragraph (assumed initially to be separated by more than one
#   newlines) is put on a single line.
#
# SEE ALSO
#
#   fmt(1)
#

BEGIN {
  inpara = 0
}

{
  if ($0 ~ /^[ \t]*$/) {
    # Add an extra break if we're just coming out of
    # a paragraph.
    if (inpara)
      printf("\n")

    inpara = 0
    printf("\n")
  }
  else {
    # Squeeze whitespace.
    sub(/^[ \t]+/, "", $0)
    sub(/[ \t]+$/, "", $0)
    sub(/[ \t]+/, " ", $0)

    if (inpara)
      printf(" %s", $0)
    else
      printf("%s", $0)

    inpara = 1
  }
}

END {
  if (inpara)
    printf("\n")
}