print_brithdays.sh

#!/bin/bash
########################################################################
#    Author: Henning Hollermann, laclaro@mail.com                      #
#                                                                      #
#    This program is free software: you can redistribute it and/or     #
#    modify it under the terms of the GNU General Public License       #
#    as published by the Free Software Foundation, either version 3    #
#    of the License, or (at your option) any later version             #
#                                                                      #
#    This program is distributed in the hope that it will be useful,   #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of    #
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the      #
#    GNU General Public License for more details.                      #
#                                                                      #
#    You should have received a copy of the GNU General Public License #
#    along with this program. If not, see <http://gnu.org/licenses/>.  #
#                                                                      #
#    Bash-Script read list of birthday dates and names with lines      #
#    "dd.mm.yyyy NAME" and prints birthdays that are nearby as con-    #
#    figured.                                                          #
#                                                                      #
#    Written in simple bash and awk                      .             #
#                                                                      #
########################################################################

# SETTINGS
birthday_list=$HOME/.geburtstagsliste
TOLERANCE=5
DAY="$(date +%d)"
MONTH="$(date +%m)"
YEAR="$(date +%Y)"
# Sort file every 6 hours
SORT=6

# START SCRIPT
if [ ! -r $birthday_list ]; then
    echo "Error: file $birthday_list not found or not readable." 1>&2
    exit 1
fi

# sort list (so you can easily add birthdays, right at the bottom)
if [ $(find $birthday_list -mmin +$(($SORT*60)) -type f 2>/dev/null) ]; then
    sort -n +1 -2 -t'.' $birthday_list -o $birthday_list
fi

awk '
    BEGIN {FS="[.]+|[ \t]+"; N=0; };
    {if ( $2==('$MONTH') && $1<=('$DAY'+'$TOLERANCE') && $1>=('$DAY'-'$TOLERANCE') ) {
        day=$1; month=$2; year=$3; $1=$2=$3=""; gsub ("^[ \t]+", "", $0); name=$0;
        monthnamecommand="date --date="month"/"day" +%B";
        monthnamecommand | getline monthname;
        message = day". " monthname" "name;
        # if recent birthdays are present, add age
        if ('$YEAR'-year!='$YEAR') message = message " ("'$YEAR'-year")";
        # mark todays birthdays
        if (day == '$DAY') message="> "message;
        print message;
        N = N+1;
    }}
    END { if (N==0) print "Keine zeitnahen Geburtstage"}
' $birthday_list