Remove old events from a big ics calendar file

README.md

Removes all events preceeding a given year from an .ics calendar file (the kind you can find e.g. in a Radicale-based CalDAV server).

Usage:

./trim-calendar.sh Personal 2016 # removes all events starting before the year 2016 from the calendar stored in Personal.ics file

trim-calendar.sh

#!/bin/bash

# first argument - the calendar file
# second argument - the year.

# All of the events preceeding the year will be removed from the calendar.

CALENDAR_FILE=$1
YEAR=$2

temp_dir=___temp
temp_files_digits=5

# backup the calendar just in case
cp $CALENDAR_FILE $CALENDAR_FILE.bak
cp $CALENDAR_FILE.props $CALENDAR_FILE.bak.props

# split the calendar file into separate files for each event. This script creates multiple files in the form of xx00000
total_files=`csplit -n $temp_files_digits $CALENDAR_FILE '/BEGIN:VEVENT/' {*} | wc -l`

echo "total events found: " $total_files

mkdir -p $temp_dir

# move the events to a separate temp directory
mv xx* $temp_dir

cd $temp_dir

grep -R DTSTART . | sed -s "s/\.\/\(xx[0-9]\+\).*:\([0-9]\{4\}\).*/\1 \2/g" | awk '{if($2>=2016) print $1;}' | xargs -L 1 cat > events

cat xx00000 events xx`printf "%05d" $((total_files-1))` > $CALENDAR_FILE

cd ../
rm $CALENDAR_FILE
mv $temp_dir/$CALENDAR_FILE $CALENDAR_FILE

rm -rf $temp_dir

If you're using MacOS then you will need to brew install coreutils and change csplit on line 19 to gcsplit, otherwise you will see a csplit: *}: bad repetition count error.

Additionally, you will need to change sed on line 30 to gsed.

Thanks for the work but as @codiflow pointed out this script does not work as-is and should not be executed blindly.

Here is a reworked edition of this script which is save to use and avoids these pitfalls:
https://gist.github.com/ewaldbenes/0067b79250b4dc65591bc606325ce90e