sorted_diff.sh - Show differences for sorted inputs.

sorted_diff.sh

#!/usr/bin/env bash
#
# sorted_diff.sh - Show differences for sorted inputs.
# Copyright (c) 2019 Koichi OKADA. All right reserved.
# This script distributed under the MIT license.
#

# Note:
# This script is wastefull.
# Use the `join` command included in the coreutils.
# `sorted_diff diff`  is same to `join -v1 -v2`,
# `sorted_diff left`  is same to `join -v1`,
# `sorted_diff right` is same to `join -v2`,
# and
# `sorted_diff same`  is same to `join`.

function sorted_diff () # <mode> <lfile> <rfile>
# Show differences for sorted inputs.
#
# Args:
#   <mode>           : one of {diff|left|right|same}
#   <lfile>, <rfile> : files to check differences
{
  (( $# != 3 )) && { echo -e "\e[31;1mError: \e[0m Wrong noumber of arguments."; return 1; }
  [[ ! "${1:0:1}" =~ [dlrs] ]] && { echo -e "\e[31;1mError: \e[0m unknown mode: $1"; return 1; }
  awk -v m="${1:0:1}" '
    BEGIN {
      while(getline < ARGV[1]) l[nl++] = $0;
      while(getline < ARGV[2]) r[nr++] = $0;
      for (il = ir = 0; il < nl && ir < nr;) {
        if      (l[il] == r[ir]) {if (m == "s"            ) print l[il]; il++; ir++;}
        else if (l[il] <  r[ir]) {if (m == "d" || m == "l") print l[il]; il++;}
        else if (l[il] >  r[ir]) {if (m == "d" || m == "r") print r[ir]; ir++;}
      }
      for (;il < nl; il++)        if (m == "d" || m == "l") print l[il];
      for (;ir < nr; ir++)        if (m == "d" || m == "r") print r[ir];
    }
  ' "$2" "$3"
}

[ "$(readlink -f -- "$0")" = "$(readlink -f -- "$BASH_SOURCE")" ] && {
  (( $# == 3 )) && sorted_diff "$@" || echo "Usage: ${0##*/} <mode={diff|left|right|same}> <lfile> <rfile>"
}